Vehicular speed reduction control device

【0001】

[Technical field to which the invention belongs]

The present invention relates to a vehicle deceleration control device that cuts fuel and performs regenerative braking when the vehicle is decelerated.

【0002】

[Conventional technology]

In recent years, hybrid vehicles equipped with two types of power sources having different characteristics, an engine and an electric motor, have been developed and put into practical use. In this hybrid vehicle, the driving forces of the two types of power sources mentioned above are optimally combined according to the situation to make the best use of the advantages of each power source and to compensate for the disadvantages. Therefore, it is possible to improve the fuel consumption rate and the emission performance while sufficiently ensuring the power performance of the vehicle.

【0003】

Further, as one aspect of the hybrid vehicle, there is one using an electric motor (motor generator) having a function of a generator. In this type of hybrid vehicle, the drive wheels rotate the motor generator during deceleration and braking. At this time, the motor generator is operated as a generator, and a part of the kinetic energy of the vehicle is converted into electric energy and recovered (regenerated) in the battery. A braking force acts on the drive wheels due to this regeneration, and the vehicle is decelerated.

【0004】

On the other hand, a technology that suppresses unnecessary fuel consumption and improves the running fuel efficiency of a vehicle by stopping the fuel supply to the engine when decelerating a vehicle that does not require the output of the engine, that is, by performing a so-called fuel cut. It has been known.

【0005】

Then, in the hybrid vehicle, a technique has been proposed in which fuel is cut during vehicle deceleration and the motor generator is controlled so as to generate a predetermined regenerative braking force (see, for example, Patent Document 1).

【0006】

Prior art documents relating to the present invention include Patent Documents 2 to 5 shown below in addition to Patent Document 1.

【0007】

[Patent Document 1]

Japanese Unexamined Patent Publication No. 10-336804 [Patent Document 2]

Japanese Unexamined Patent Publication No. 10-280990 [Patent Document 3]

Japanese Unexamined Patent Publication No. 8-88905 [Patent Document 4]

Japanese Unexamined Patent Publication No. 2000-104597 [Patent Document 5]

Japanese Unexamined Patent Publication No. 2000-272381 [0008]

[Problems to be Solved by the Invention]

By the way, in an engine provided with a so-called three-way catalyst that oxidizes carbon monoxide CO and hydrocarbon HC in the exhaust and reduces nitrogen oxide NOx as an exhaust purification catalyst in the exhaust passage, the engine is, for example, in a high rotation range. When the vehicle is decelerated while being driven in, the following phenomena occur. This is because the three-way catalyst has an action (oxygen storage action) of temporarily storing oxygen associated with the reduction of nitrogen oxide NOx and releasing it during oxidation of carbon monoxide CO and hydrocarbon HC. On the other hand, when the engine is operated in a high rotation range, the amount of air flowing through the engine is relatively large, and the amount of oxygen stored in the three-way catalyst is also large accordingly. Therefore, when the fuel supply is restarted and combustion is performed after the fuel is cut, carbon monoxide CO and hydrocarbon HC are oxidized, but the reduction reaction of nitrogen oxide NOx does not proceed. As a result, nitrogen oxide NOx may not be sufficiently purified and exhaust emissions may not be sufficiently reduced.

【0009】

In this regard, although the above-mentioned Document 1 describes that the motor generator is generated with a regenerative braking force to decelerate the vehicle in accordance with the fuel cut, the purification of the exhaust gas is not considered. Therefore, the above-mentioned problem regarding purification of nitrogen oxide NOx still remains.

【0010】

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a vehicle deceleration control device capable of achieving both reduction of exhaust emissions and improvement of deceleration performance.

【0011】

[Means for solving problems]

Hereinafter, means for achieving the above object and its action and effect will be described. In the invention according to claim 1, the engine mounted on the vehicle and purifying the exhaust gas by an exhaust purification catalyst, the regenerative braking means connected to the axle of the vehicle so as to be regenerative braking, and the vehicle. Detection of deceleration by the deceleration detecting means in a vehicle deceleration control device including a deceleration detecting means for detecting deceleration and a fuel supply stopping means for stopping fuel supply to the engine in response to detection of deceleration by the deceleration detecting means. Therefore, a deceleration control means for decelerating the vehicle by the regenerative braking means is further provided prior to the fuel supply stop by the fuel supply stop means.

【0012】

According to the above configuration, when the deceleration of the vehicle is detected by the deceleration detecting means, the vehicle is first decelerated by the regenerative braking means, and then the fuel supply to the engine is stopped. That is, when the deceleration of the vehicle is detected, fuel is continuously supplied and combustion is performed for a predetermined period from the detection. Therefore, for example, when the operating state of the engine before deceleration is in the high rotation range, the amount of oxygen stored in the exhaust purification catalyst increases, but this oxygen is the oxygen of carbon monoxide and hydrocarbons in the exhaust as combustion continues. Used for oxidation. The amount of oxygen stored in the exhaust gas purification catalyst is less immediately before the fuel supply is stopped than immediately after the vehicle deceleration is detected.

【0013】

During the above period, combustion is continued, and the output shaft of the engine is rotated by the energy generated by the combustion. Therefore, it is difficult to decelerate the vehicle by the engine alone to obtain a desired deceleration. However, the regenerative braking means is driven by the rotation of the axle. At this time, the regenerative braking means is operated as a generator, and a part of the kinetic energy of the vehicle is converted into electric energy and recovered. The regenerative braking force generated by this power generation compensates for the above-mentioned shortage of deceleration. As a result, the vehicle can be decelerated at a desired deceleration.

【0014】

Then, when the above period elapses, the fuel supply to the engine is stopped, the fuel consumption is reduced, and the fuel consumption rate is improved. When the fuel supply is stopped, the output shaft of the engine is rotated by the axle. At this time, a braking force is generated by the friction torque of the engine (friction resistance accompanying the rotation of the engine), so that the vehicle is in a decelerated state.

【0015】

When the fuel supply is restarted, the amount of oxygen stored in the exhaust gas purification catalyst is smaller than that before the deceleration as described above. Therefore, when the fuel supply is stopped immediately after the deceleration is detected. In comparison, nitrogen oxides are better reduced and purified.

【0016】

As described above, according to the invention of claim 1, it is possible to achieve both reduction of exhaust emissions and improvement of deceleration performance. In the invention according to claim 2, in the invention according to claim 1, the fuel supply stopping means supplies fuel to the engine on condition that a predetermined time elapses from the detection of deceleration by the deceleration detecting means. It is assumed that the deceleration control means decelerates the vehicle by the regenerative braking means during the period from the detection of the deceleration by the deceleration detecting means to the stop of the fuel supply by the fuel supply stopping means.

【0017】

According to the above configuration, the fuel supply stop means does not stop the fuel supply until a predetermined time elapses, based on the time when the deceleration detection means of the vehicle detects the deceleration of the vehicle. During this period, the vehicle is decelerated by the regenerative braking force of the regenerative braking means. Then, when the predetermined time has elapsed, the fuel supply to the engine is stopped. As described above, since the vehicle is decelerated and the fuel supply is stopped by the regenerative braking means according to the elapsed time after the detection of deceleration, the effect of the invention according to claim 1 described above is ensured. can do.

【0018】

In the invention according to claim 3, in the invention according to claim 1 or 2, the deceleration control means is switched from the fuel supply to the stop by the fuel supply stop means, and is more than before the fuel supply stop. It is assumed that the regenerative braking force of the regenerative braking means is reduced.

【0019】

According to the above configuration, a braking force is generated by the friction torque of the engine when the fuel supply is stopped by the fuel supply stopping means. On the other hand, at this time, the deceleration control means makes the braking force of the regenerative braking means smaller than that before the fuel supply was stopped. Therefore, it is possible to prevent the braking force acting on the entire vehicle from becoming excessively large as the braking force of the engine increases.

【0020】

In the invention according to claim 4, in the invention according to claim 3, the deceleration control means applies the regenerative braking force of the regenerative braking means immediately after switching from the fuel supply to the stop by the fuel supply stopping means. It is assumed that the size is gradually reduced.

【0021】

Here, when the supply of fuel to the engine is stopped from the state where the fuel is being supplied, the braking force of the engine due to the friction torque gradually increases, and it may take time to reach the desired magnitude. obtain. In this regard, in the invention according to claim 4, immediately after switching to the fuel supply stop, the regenerative braking force of the regenerative braking means is gradually reduced by the deceleration control means. Therefore, the sum of the braking force of the engine and the regenerative braking force of the regenerative braking means can be made substantially constant before and after the fuel supply is stopped, and the deceleration according to the driver's request can be obtained to improve drivability. It becomes possible to plan.

【0022】

BEST MODE FOR CARRYING OUT THE INVENTION

(First Embodiment) Hereinafter, a first embodiment embodying the present invention will be described with reference to FIGS. 1 to 5.

【0023】

As shown in FIG. 1, the vehicle is equipped with an engine such as a gasoline engine or a diesel engine (Fig. 1 shows a gasoline engine) 13 and a motor generator (sometimes referred to simply as a motor) 14 as power sources. There is.

【0024】

In the engine 13, air is sucked into each combustion chamber 16 through an intake passage 17, and fuel is injected and supplied from a fuel injection valve 18. When the mixture of fuel and air is ignited by the spark plug 19, the mixture burns, the piston 21 reciprocates, and the crankshaft 22, which is the output shaft of the engine 13, rotates. The exhaust gas generated by the combustion of the air-fuel mixture is discharged from each combustion chamber 16 to the exhaust passage 23, and is purified by the exhaust purification catalyst 24 in the middle of the exhaust passage 23. As the exhaust gas purification catalyst 24, a three-way catalyst that simultaneously oxidizes carbon monoxide CO and hydrocarbon HC in the exhaust gas and reduces nitrogen oxide NOx and purifies them into carbon dioxide, water vapor, and nitrogen is used. Has been done.

【0025】

The output adjustment of the engine 13 is realized by driving the throttle valve 25 provided in the intake passage 17 by the throttle actuator 26 and adjusting the opening degree (throttle opening degree) of the throttle valve 25. That is, by adjusting the throttle opening, the amount of intake air to the engine 13 changes, the fuel injection amount is controlled in response to the change, and the amount of the air-fuel mixture filled in the combustion chamber 16 changes. Output is adjusted. The throttle opening degree is adjusted by driving the throttle actuator 26 according to the amount of depression of the accelerator pedal (not shown) operated by the driver.

【0026】

The motor generator 14 is an electric motor having a power generation function, and is also used as a regenerative braking means. The motor generator 14 includes a rotor 14a and a stator coil 14b arranged around the rotor 14a. In this motor generator 14, the rotor 14a is continuously subjected to magnetic force from the rotating magnetic field by energizing the stator coil 14b and making the rotating magnetic field applied to the stator coil 14a have a phase advanced with respect to the rotation of the rotor 14a. And rotate. That is, the motor generator 14 functions as an electric motor.

【0027】

Further, in the motor generator 14, power generation is performed by assuming that the rotating magnetic field applied to the stator coil 14b has a phase delayed with respect to the rotation of the rotor 14a. At this time, the larger the current flowing through the stator coil 14b, the larger the power generation output can be obtained. In addition, the drive torque consumed to obtain the power generation output also becomes large, and this drive torque acts as a regenerative braking force.

【0028】

The planetary gear device 15 is used as a mechanism for outputting the powers of the engine 13 and the motor generator 14 individually or in combination. As the planetary gear device 15, a known double pinion type is used in which a sun gear 27, a carrier 28, and a ring gear 29 are used as rotating elements, and a differential action is performed between these three rotating elements. The sun gear 27 is an external gear, and the ring gear 29 is an internal gear arranged concentrically with the sun gear 27. The carrier 28 holds the first pinion gear 31 that meshes with the sun gear 27 and the second pinion gear 32 that meshes with the first pinion gear 31 and the ring gear 29 so as to rotate and revolve. Of these rotating elements, the crankshaft 22 of the engine 13 is connected to the sun gear 27, and the rotor 14a of the motor generator 14 is connected to the carrier 28. A brake B1 for selectively fixing the ring gear 29 is provided between the ring gear 29 and the casing 33.

【0029】

The planetary gear device 15 is provided with a first clutch C1 and a second clutch C2 in order to selectively transmit power to the output shaft 34. The first clutch C1 selectively connects the carrier 28 and the output shaft 34, and the second clutch C2 selectively connects the ring gear 29 and the output shaft 34.

【0030】

The output shaft 34 is connected to the input shaft 36 of the transmission 35. This transmission 35 increases or decreases the drive torque by changing the gear ratio, which is the ratio of the rotation speed of the input shaft 36 to the rotation speed of the output shaft 37, and is used here by a belt-type continuously variable transmission. Has been done. This type of continuously variable transmission is equipped with a drive pulley 38 and a driven pulley 39 whose groove width can be changed, and the winding radius of the belt 41 with respect to both pulleys 38 and 39 is adjusted by changing the groove width. It is configured to continuously change the gear ratio.

【0031】

The output shaft 37 of the transmission 35 is connected to the differential device 43 via a gear-type power transmission mechanism 42 composed of a plurality of gear groups. The differential device 43 is connected to the left and right axles 45, each of which is provided with a drive wheel 44. Then, the power transmitted from the transmission 35 to the differential device 43 via the gear type power transmission mechanism 42 is distributed to the left and right axles 45 by the differential device 43 and transmitted to the drive wheels 44.

【0032】

Further, a high voltage battery 52 is connected to the motor generator 14 via an inverter 51. The inverter 51 makes the supply of electric energy from the high-voltage battery 52 to the motor generator 14 variable by a switching operation, and makes the rotation speed of the motor generator 14 variable. Further, the inverter 51 supplies the electric power generated by the motor generator 14 to the high voltage battery 52 by the switching operation. The high-voltage battery 52 is exclusively used as a power source for driving the motor generator 14, and when the motor generator 14 is operating as a generator, it stores the generated electric power. A low-voltage battery 54 is connected to the high-voltage battery 52 via a DC / DC converter 53, which is a type of converter. The low-voltage battery 54 is used as a power source for driving various auxiliary machines (not shown), ECUs 61, 62, etc., which will be described later. The DC / DC converter 53 steps down the voltage of the high-voltage battery 52 to charge the low-voltage battery 54.

【0033】

Further, various sensors such as a crank angle sensor 56, an accelerator sensor 57, and a vehicle speed sensor 58 are attached to the vehicle to detect the state of each part. The crank angle sensor 56 outputs a signal each time the crankshaft 22 of the engine 13 rotates by a certain angle. This signal is used to calculate the engine rotation speed Ne, which is the rotation speed of the crankshaft 22. The accelerator sensor 57 detects the amount of depression of the accelerator pedal by the driver (accelerator opening degree). The vehicle speed sensor 58 detects the vehicle speed, which is the traveling speed of the vehicle. The accelerator sensor 57 and the vehicle speed sensor 58 constitute a deceleration detecting means for detecting the deceleration of the vehicle.

【0034】

In order to control the operation of each part of the motor generator 14, the transmission 35, etc. based on the detected values of these sensors 56 to 58, the vehicle is a hybrid electronic control unit composed mainly of a microcomputer (hereinafter, "hybrid"). "ECU") 61 is provided. In this hybrid ECU 61, the central processing unit (CPU) performs arithmetic processing according to the control program and initial data stored in the read-only memory (ROM) based on the detected values of the various sensors 56 to 58, and the arithmetic result is obtained. Various controls are executed based on. The calculation result by the CPU is temporarily stored in the random access memory (RAM). The hybrid ECU 61 is communicably connected to an engine electronic control device (hereinafter referred to as an engine ECU) 62 that controls each part of the engine 13.

【0035】

The flowchart of FIG. 2 shows a "torque calculation routine" for calculating the vehicle driving force (required torque T) and the like required by the driver among the processes executed by the hybrid ECU 61. Further, the flowchart of FIG. 3 shows an "engine torque control routine" for controlling the torque of the engine 13 among the processes executed by the engine ECU 62. These routines are repeatedly executed at predetermined timings, for example, at regular intervals. These processes are performed based on the fuel cut (F / C) running flag F. The fuel cut in progress flag F is set to "off" when the fuel cut is not being performed, and is set to "on" when the fuel cut is being performed. The setting of the fuel cut executing flag F is performed in the engine torque control routine. The setting of "ON" of the fuel cut executing flag F is that a predetermined time α (for example, 1 second) elapses after the engine ECU 62 receives the fuel cut command (negative required engine torque Te) from the hybrid ECU 61. It is done on the condition.

【0036】

In the torque calculation routine of FIG. 2, the hybrid ECU 61 first determines in step 100 whether or not the predetermined deceleration fuel cut condition is satisfied. Here, the fuel cut during deceleration improves the running fuel efficiency of the vehicle by suppressing unnecessary fuel consumption by stopping the fuel supply to the engine 13 during deceleration running of the vehicle that does not require the output of the engine 13. It is done for the purpose of doing. Examples of the fuel cut condition during deceleration include "the accelerator pedal is not depressed while the vehicle is running (accelerator off)". In order to determine whether or not the fuel cut condition during deceleration is satisfied, for example, the vehicle speed by the vehicle speed sensor 58 is equal to or higher than a predetermined value (0 or a value close to 0), and the accelerator opening degree by the accelerator sensor 57 is predetermined. Determine if it is less than or equal to the value (0 or close to it). In this way, in step 100, the deceleration of the vehicle is detected.

【0037】

If the determination condition of step 100 is not satisfied, that is, if the driver does not intend to decelerate, the process proceeds to step 160, and the vehicle driving force (required torque T) required by the driver is calculated. In this calculation, for example, a two-dimensional map in which the relationship between the vehicle speed and the accelerator opening and the required torque T is defined in advance is referred to. In this map, for example, the required torque T is set to increase as the accelerator opening increases and the vehicle speed decreases. Further, when the vehicle speed is high and the accelerator opening is 0%, the required torque T is set to a negative value. Then, in step 160, the required torque T corresponding to the vehicle speed by the vehicle speed sensor 58 and the accelerator opening degree by the accelerator sensor 57 is calculated from the map. Instead of the map described above, the required torque T may be calculated according to a predetermined calculation formula.

【0038】

Subsequently, of the required torque T, the required engine torque Te, which is the share of the engine 13, and the required motor torque Tm, which is the share of the motor generator 14, are calculated. For example, the maximum torque that the engine 13 can output is obtained, and this is defined as the required engine torque Te. Therefore, for example, the maximum torque that can be output by the engine 13 is obtained in advance by experiments or the like for each engine rotation speed Ne. Then, the engine rotation speed Ne detected by the crank angle sensor 56 is read, the maximum torque corresponding to the engine rotation speed Ne is calculated, and this is set as the required engine torque Te. Further, the required engine torque Te is subtracted from the above-mentioned required torque T, and the subtraction result is defined as the required motor torque Tm. In this way, the required engine torque Te and the required motor torque Tm are calculated.

【0039】

Next, in step 170, the required engine torque Te obtained in step 160 is transmitted to the engine ECU 62. Further, in step 180, the motor generator 14 functions as an electric motor by controlling the inverter 51 based on the required motor torque Tm obtained in step 160. By this control, in the motor generator 14, a rotating magnetic field having a phase advanced with respect to the rotation of the rotor 14a is generated in the stator coil 14b, and the rotor 14a rotates by receiving a magnetic force from this rotating magnetic field, which corresponds to the required motor torque Tm. Generates torque. Then, after passing through the process of step 180, the torque calculation routine is terminated.

【0040】

By the way, if the above-mentioned determination condition of step 100 is satisfied, that is, if the driver releases the accelerator pedal with the intention of decelerating while the vehicle is running, in step 110, in the same manner as in step 160 described above, Obtain the required torque T based on the vehicle speed and accelerator opening. In this case, the accelerator opening is 0% (fully closed), and the required required torque T is a negative value.

【0041】

Further, in step 110, the friction torque (friction resistance torque) of the engine 13 at that time is obtained , and this is set as the required engine torque Te. Therefore, for example, the friction torque of the engine 13 is obtained in advance by an experiment or the like for each engine rotation speed Ne. Then, the engine rotation speed Ne detected by the crank angle sensor 56 is read, the friction torque corresponding to the engine rotation speed Ne is calculated, and this is set as the required engine torque Te.

【0042】

Next, in step 120, the engine ECU 62 is requested to cut the fuel in the engine 13 by transmitting the negative required engine torque Te obtained in step 110 to the engine ECU 62.

【0043】

Next, in steps 130 to 150, the required motor torque Tm is calculated based on the required torque T in step 110. At this time, the method of calculating the required motor torque Tm is different depending on the state of the flag F during fuel cut execution. More specifically, in step 130, it is determined whether or not the fuel cut executing flag F is on. As described above, the fuel cut executing flag F is off until a predetermined time α elapses after the negative required engine torque Te is output to the engine ECU 62, and is switched to on after that.

【0044】

If the determination condition in step 130 is not satisfied (the fuel cut executing flag F is off), the required motor torque Tm is calculated with the required engine torque Te as "0" in step 140. Although the required motor torque Tm is obtained by subtracting the required engine torque Te from the required torque T, in this case, since Te = 0, the required torque T becomes the required motor torque Tm. Since the required torque T is a negative value, the required motor torque Tm is a negative value.

【0045】

On the other hand, when the determination condition of step 130 is satisfied (the fuel cut executing flag F is on), the request is made in step 150 by using the negative required engine torque Te obtained in step 110. Calculate the motor torque Tm. That is, the required engine torque Te is subtracted from the required torque T, and the subtraction result is defined as the required motor torque Tm. In this case, the required motor torque Tm obtained becomes "0" or a value close to the value obtained in step 140.

【0046】

Then, after the process of step 140 or 150 is performed, the process of step 180 described above is performed. After the process of step 140, in step 180, the motor generator 14 functions as a generator by controlling the inverter 51 based on the negative required motor torque Tm. By this control, in the motor generator 14, a rotating magnetic field having a phase delayed with respect to the rotation of the rotor 14a is generated in the stator coil 14b. A power generation output of a magnitude corresponding to the current flowing through the stator coil 14b is obtained and stored (recovered) in the high-voltage battery 52. Further, the driving torque is consumed in order to obtain the power generation output, and the vehicle is decelerated by the regenerative braking force accompanying the consumption.

【0047】

On the other hand, when the process of step 150 is passed, in step 180, the inverter 51 is controlled based on the required motor torque Tm of "0" or close to it. Due to this control, no current is passed through the stator coil 14b, or even if it is passed, it is very small.

【0048】

In the torque calculation routine described above, the deceleration control means is realized by the processing of steps 100, 130, and 140. Next, the "engine torque control routine" performed by the engine ECU 62 will be described.

【0049】

The engine ECU 62 first determines in step 210 whether or not the required engine torque Te has been received from the hybrid ECU 61. The required engine torque Te of interest was transmitted in step 120 or 170 of the torque calculation routine. If the determination condition of step 210 is not satisfied, the engine torque control routine is terminated as it is.

【0050】

On the other hand, if the determination condition of step 210 is satisfied, it is determined in step 220 whether or not the required engine torque Te is a negative value. If this determination condition is not satisfied (Te 0), that is, if the hybrid ECU 61 does not require a fuel cut, in step 260, the throttle actuator 26 is driven to generate the required engine torque Te in the engine 13. Control to adjust the opening of the throttle valve 25. By this adjustment, the amount of intake air to the engine 13 changes, the fuel injection amount is controlled in response to the change, the amount of the air-fuel mixture filled in the combustion chamber 16 changes, and the output of the engine 13 is adjusted. , A torque corresponding to the required engine torque Te (Te 0) is generated. Subsequently, in step 270, the fuel cut executing flag F is switched off, and then the engine torque control routine is temporarily terminated.

【0051】

On the other hand, when the determination condition of step 220 is satisfied (Te <0), that is, when the hybrid ECU 61 requests fuel cut, in step 230, a predetermined time α is set from the reception of the required engine torque Te. Determine if it has passed. If this determination condition is not satisfied (predetermined time α has not elapsed), the engine torque control routine is terminated as it is. Therefore, until the predetermined time α elapses, the fuel injection is continued even though the negative required engine torque Te is commanded from the hybrid ECU 61. In other words, the fuel cut is not performed (the start time of the fuel cut is delayed) until the predetermined time α elapses.

【0052】

This is because if the engine 13 is rotating in the high rotation range before deceleration, the amount of oxygen stored in the exhaust purification catalyst (three-way catalyst) 24 is relatively large, and after the fuel is cut in this state. This is because if the fuel supply is resumed, the purification of nitrogen oxide NOx may not proceed. Therefore, by delaying the fuel cut (continuing the fuel supply), oxygen is consumed for the oxidation of carbon monoxide CO and hydrocarbon HC, and the purification of nitrogen oxide NOx is promoted.

【0053】

On the other hand, if the determination condition of step 230 is satisfied (predetermined time α elapses), it is considered that the amount of oxygen stored in the three-way catalyst is reduced due to the above combustion. Therefore, fuel injection is performed in step 240. The energization of the valve 18 is stopped, and the fuel injection from the fuel injection valve 18 to the combustion chamber 16 is temporarily stopped. Then, in step 250, after setting the fuel cut executing flag F to ON, a series of processes of the engine torque control routine is terminated.

【0054】

The fuel supply stop means is realized by the processes of steps 100, 110, 120 in the torque calculation routine described above and steps 210 to 240 in the engine torque control routine.

【0055】

When each process is performed according to the torque calculation routine and the engine torque control routine, the required engine torque Te, the fuel cut executing flag F, the vehicle acceleration G, the battery power, and the like change as shown in FIG. 5, for example. FIG. 5 shows a case where the accelerator pedal is released at the timing t1 (the accelerator is off), the fuel cut condition during deceleration is satisfied, and the fuel cut is started at the timing t2 after the predetermined time α has elapsed. Therefore, the fuel cut executing flag F is off before the timing t2, and is switched to on at the timing t2.

【0056】

Note that FIG. 4 shows a case (comparative example) in which the same processing as in step 150 is performed as the processing in step 140 of the torque calculation routine. In this case, the required engine torque Te (<0) obtained in step 110 is used to calculate the required motor torque Tm regardless of the fuel cut executing flag F.

【0057】

In FIG. 4, when the accelerator is released at the timing t1, the negative value obtained in step 110 is used as the required engine torque Te used for calculating the required motor torque Tm (step 140). Since the required torque T is negative and the required engine torque Te is negative, there is no or very little burden of the required motor torque Tm in the required torque T. Therefore, the required motor torque Tm is "0" or a value close to it.

【0058】

On the other hand, fuel injection and combustion are performed during the period ΔT from the timing t1 when the transmission of the negative required engine torque Te is started to the timing t2 when the predetermined time α elapses (step 220 230). Return). Therefore, the negative torque (braking force) that the engine 13 should bear cannot be obtained during this period ΔT. In addition, the torque generated by the motor generator 14 during this period ΔT is 0 or a value close to it as described above. Almost no braking force is obtained by either the engine 13 or the motor generator 14. Therefore, the torque transmitted to the drive wheels 44 through the planetary gear device 15, the transmission 35, the gear type power transmission mechanism 42, etc. (the sum of the torque generated by the engine 13 and the torque generated by the motor generator 14) is the driver. Is greater than the negative torque required by. Since there is no element that decelerates the vehicle other than the running resistance, the acceleration G of the vehicle is approximately "0", and the driver cannot feel the intended deceleration feeling during the period ΔT. In addition, while the motor generator 14 does not generate regenerative power during the period ΔT, power is supplied (taken out) to the auxiliary equipment, so the battery power (current x voltage) is close to "0". It changes on the side.

【0059】

Then, after the timing t2, the fuel is cut according to the negative required engine torque Te (step 220 230 240), so that the torque of the engine 13 becomes negative. The required torque T is covered by this torque. Therefore, the required motor torque Tm is substantially "0" as before the timing t2, but the torque transmitted to the drive wheels 44 is substantially equal to the torque required by the driver. The acceleration G of the vehicle is in a negative state, that is, a deceleration state, and the driver's intended deceleration feeling is obtained.

【0060】

On the other hand, in the first embodiment, in the torque calculation routine, the required engine torque Te is set to "0" and used for calculating the required motor torque Tm as the process of step 140. By setting the required engine torque Te to "0" in this way, the part in charge of the motor generator 14 for realizing the required torque T is generated. In this case, since the required torque T is negative, the required motor torque Tm in the period ΔT becomes a negative value as shown in FIG. By controlling the inverter 51 based on this negative required motor torque Tm, the motor generator 14 is operated as a generator and a regenerative braking force is generated. The electric power obtained by the power generation is stored (recovered) in the high voltage battery 52.

【0061】

Therefore, almost no braking force is generated in the engine 13 during the period ΔT, but the shortage is compensated by the regenerative braking force of the motor generator 14. The torque transmitted to the drive wheels 44 is substantially the same as the torque required by the driver (required torque T). As a result, the acceleration G of the vehicle becomes negative, and a desired deceleration feeling can be obtained.

【0062】

The timing after t2 is the same as in FIG. 4 described above. In this case, since the fuel is cut according to the negative required engine torque Te, the torque of the engine 13 becomes negative, and the required torque T is covered by this torque. Therefore, the required motor torque Tm is approximately "0". The torque transmitted to the drive wheels 44 is substantially equal to the torque required by the driver (required torque T). The acceleration G of the vehicle becomes negative, and the feeling of deceleration intended by the driver continues to be obtained after timing t2.

【0063】

According to the first embodiment described in detail above, the following effects can be obtained. (1) When the fuel cut condition at the time of deceleration is satisfied, the vehicle is decelerated by the motor generator 14 prior to the fuel cut (steps 100, 110, 130, 140, 180). That is, the fuel is not cut immediately even if the deceleration of the vehicle is detected, but the combustion is continued for a while and the fuel is cut after the predetermined time α has elapsed. Therefore, for example, when the operating state of the engine 13 before deceleration is in the high rotation range, the amount of oxygen stored in the exhaust purification catalyst 24 is relatively large, but carbon monoxide CO in the exhaust generated with the continuation of fuel is generated. Oxygen can be consumed to an appropriate amount by oxidizing the hydrocarbon HC and the hydrocarbon.

【0064】

During the period ΔT from the deceleration detection to the elapse of the predetermined time α, combustion is continuously performed in the engine 13, and the crankshaft 22 of the engine 13 is rotated by the energy generated by the combustion. In addition, it takes a certain amount of time for the engine speed to decrease due to the shift delay in the transmission 35. Therefore, it is difficult to decelerate the vehicle only by the engine 13 to obtain a desired deceleration. However, the rotor 14a of the motor generator 14 is rotated by the drive wheels 44. At this time, the motor generator 14 is operated as a generator, and a power generation output having a magnitude corresponding to the current flowing through the stator coil 14b is obtained and stored (recovered) in the high-voltage battery 52. Further, the driving torque is consumed in order to obtain the power generation output, and the regenerative braking force accompanying the consumption compensates for the shortage of the deceleration described above. As a result, the vehicle can be decelerated at a desired deceleration, and a feeling of deceleration of the vehicle intended by the driver can be obtained.

【0065】

When the above period ΔT elapses, the fuel is cut, the fuel consumption is reduced, and the fuel consumption rate is improved. The engine 13 is driven by the drive wheels 44 along with this fuel cut, but at this time, a braking force is generated by the friction torque of the engine 13 (friction resistance accompanying the rotation of the engine 13), so that the vehicle is in a decelerated state.

【0066】

When the fuel cut is completed and the fuel supply is restarted, the amount of oxygen stored in the exhaust purification catalyst 24 is smaller than that before the deceleration as described above, so that the fuel is cut immediately after the deceleration is detected. Nitrogen oxide NOx is reduced and purified better than in the case of.

【0067】

As described above, according to the first embodiment, it is possible to achieve both reduction of exhaust emissions and improvement of deceleration performance. (2) Since fuel supply and combustion are continued from the detection of vehicle deceleration until a predetermined time α elapses, the braking force generated by the engine 13 is smaller than that at the time of fuel cut. Therefore, if a negative value is used as the required engine torque Te from the detection of deceleration of the vehicle until a predetermined time α elapses as in the case of fuel cut, there is a possibility that an erroneous required motor torque Tm is calculated.

【0068】

In this regard, in the first embodiment, the required motor torque Tm is calculated in a mode different from that at the time of fuel cut from the detection of deceleration of the vehicle to the fuel cut (steps 130 and 140). That is, the required motor torque Tm is calculated with Te = 0. Considering that the braking force of the engine 13 is small in this way, it is possible to accurately obtain the required motor torque Tm. The motor generator 14 generates a regenerative braking force corresponding to the required motor torque Tm to compensate for the insufficient braking force of the engine 13, and decelerates the vehicle at the desired deceleration even in the period ΔT from the detection of deceleration of the vehicle to the start of fuel cut. You will be able to make it.

【0069】

(3) Based on the time when the deceleration of the vehicle is detected, the fuel is not cut until the predetermined time α elapses. During this period, the vehicle is decelerated by the regenerative braking force of the motor generator 14. Then, the fuel cut is started when the predetermined time α has elapsed. In this way, the motor generator 14 decelerates the vehicle and cuts fuel according to the elapsed time after the detection of deceleration, so that the effect of (1) described above can be ensured.

【0070】

(4) When switching from fuel supply to fuel cut, braking force is generated by the friction torque of the engine 13. On the other hand, at this time, the regenerative braking force of the motor generator 14 is made smaller than that before the fuel cut. Therefore, it is possible to prevent the braking force acting on the entire vehicle from becoming excessively large as the braking force of the engine 13 increases.

【0071】

(5) The motor generator 14 is operated as a generator during the period ΔT (steps 130, 140, 180). Therefore, it is possible to charge the engine 13 in preparation for assisting the engine 13 by the motor generator 14 when accelerating after the fuel is cut. It is possible to eliminate the lack of regeneration and stabilize the capacity of the high-voltage battery 52.

【0072】

(Second Embodiment) Next, a second embodiment embodying the present invention will be described with reference to FIG. In the first embodiment described above, as shown in FIG. 5, when the fuel cut starts at the timing t2, the friction torque of the engine 13 is suddenly generated, that is, the torque of the engine 13 is negative from "0". The required motor torque Tm is calculated assuming that the value is instantly switched to the value of.

【0073】

However, when the fuel is cut from the state in which the fuel is injected, the braking force of the engine 13 due to the friction torque gradually increases, and it may take time to reach a desired magnitude. Therefore, the deceleration required by the driver may not be obtained until the desired size is reached.

【0074】

Therefore, in the second embodiment, the required motor torque is calculated according to the passage of time from immediately after the determination condition of step 130 is satisfied (immediately after the timing t2 when the fuel cut is started) to the timing t3 when a certain time elapses. The required engine torque Te for is gradually reduced from "0". Along with this, the required motor torque Tm gradually increases with the passage of time in the period from timing t2 to t3. By controlling the inverter 51 based on this required motor torque Tm, the regenerative braking force of the motor generator 14 is gradually reduced. In the period from timing t2 to t3, the battery power also gradually increases, so that the power charged (recovered) by the battery increases as compared with the first embodiment.

【0075】

Therefore, according to the second embodiment, the following effects can be obtained in addition to the above-mentioned effects (1) to (5). (6) Immediately after the start of fuel cut, the regenerative braking force of the motor generator 14 is gradually reduced. Therefore, the sum of the braking force of the engine 13 and the regenerative braking force of the motor generator 14 can be made substantially constant before and after the fuel cut. The deceleration of the vehicle can be kept substantially constant before and after the fuel cut, and it is possible to obtain the deceleration according to the driver's request and improve the drivability.

【0076】

The present invention can be embodied in another embodiment shown below. -The predetermined time α may be a constant value or may be a different value depending on the conditions.

【0077】

-In the second embodiment, the value used to gradually decrease the required engine torque Te and the value used to gradually increase the required motor torque Tm during the period from timing t2 to t3 may be constant values. However, it may be different depending on the conditions.

【0078】

-The required engine torque Te in step 140 of the torque calculation routine is not limited to "0" and may be a value close to it. -In addition to the accelerator sensor 57, an idle switch may be provided to detect whether or not the driver has depressed the accelerator pedal. This idle switch is turned on, for example, when the accelerator pedal is not depressed. Therefore, when the idle switch is turned on, the driver has no intention of at least maintaining or accelerating the vehicle speed. Therefore, the idle switch signal can be used to determine the success or failure of the fuel cut condition during deceleration described above.

【0079】

-As the transmission 35, in addition to the belt type continuously variable transmission, various transmissions such as a stepped type transmission mainly composed of a planetary gear mechanism and a toroidal type continuously variable transmission are used. can do.

【0080】

In addition, the technical ideas that can be grasped from each of the above-described embodiments will be described together with their effects. (A) In the vehicle deceleration control device according to any one of claims 1 to 4, the regenerative braking means is a motor generator mounted on the vehicle as a power source and having both a rotation function and a power generation function.

【0081】

According to the above configuration, the torque of the engine can be assisted by operating the motor generator as an electric motor except during deceleration. (B) The exhaust is purified by an exhaust purification catalyst, and when the vehicle deceleration is detected, the engine is connected so that the fuel supply is stopped after a predetermined time has elapsed from the detection, and the axle of the vehicle can be regeneratively braked. A regenerative braking means, a required torque required for the vehicle, and a required engine torque required for the engine, respectively, and a torque calculating means for obtaining the required regenerative braking torque required for the regenerative braking means based on both torques. A vehicle deceleration control device including a torque control means for controlling each torque of the engine and the regenerative braking means so that the required engine torque and the required regenerative braking torque are generated. A vehicle deceleration control device characterized in that the required regenerative braking torque is calculated in a mode different from that at the time of fuel supply stop from the vehicle deceleration detection to the fuel supply stop.

【0082】

Here, the required motor torque Tm in both embodiments corresponds to the required regenerative braking torque. Further, the torque calculation means is realized by the processing of steps 110, 140, 150, 160 in the torque calculation routine. The torque control means is realized by the process of step 180 in the torque calculation routine and the process of step 260 in the engine torque control routine.

【0083】

According to the above configuration, since the fuel supply is continued until a predetermined time elapses after the deceleration of the vehicle is detected, the braking force generated by the engine is smaller than that when the fuel supply is stopped. Therefore, if the required engine torque is the same value as when the fuel supply is stopped even after the detection of deceleration of the vehicle and the elapse of a predetermined time, there is a possibility that an erroneous required regenerative braking torque is calculated.

【0084】

In this regard, in the invention described in (B) above, the required regenerative braking torque is calculated in a mode different from that at the time of stopping the fuel supply from the detection of deceleration of the vehicle to the stopping of the fuel supply. Therefore, considering that the braking force of the engine is small, it is possible to accurately obtain the required regenerative braking torque. By generating a regenerative braking force corresponding to the required regenerative braking torque in the regenerative braking means, it is possible to compensate for the insufficient braking force of the engine. As a result, the vehicle can be decelerated at a desired deceleration even during the period from the detection of deceleration of the vehicle to the stop of fuel supply.

【0085】

(C) In the vehicle deceleration control device according to (B) above, the torque calculation means uses the deviation between the required torque and the required engine torque as the required regenerative braking torque.

【0086】

(D) In the vehicle deceleration control device according to (C) above, the torque calculation means sets the required engine torque to zero and sets the required regenerative braking torque to zero during the period from the deceleration detection of the vehicle to the suspension of fuel supply. It is to be calculated.

【0087】

According to the above configuration, if a negative value is used as the required engine torque from the detection of deceleration of the vehicle until a predetermined time elapses as in the case of stopping the fuel supply, the required regenerative braking torque is zero or close to zero. The value may be calculated.

【0088】

In this respect, in the invention described in (D) above, the required engine torque is set to zero during the period from the detection of deceleration of the vehicle to the stop of fuel supply. Therefore, the required regenerative braking torque calculated based on the required torque and the required engine torque is a negative value. When a regenerative braking force corresponding to the required regenerative braking torque is generated in the regenerative braking means, the insufficient braking force of the engine is compensated and the vehicle is decelerated at a desired deceleration.

[Simple explanation of drawings]

FIG. 1 is a schematic diagram showing a configuration of a first embodiment embodying a vehicle deceleration control device of the present invention.

FIG. 2 is a flowchart showing a procedure for calculating torque such as required torque.

FIG. 3 is a flowchart showing a procedure for controlling engine torque.

FIG. 4 is a timing chart illustrating the operation when the required motor torque Tm is calculated with the required engine torque Te as a negative value in the period ΔT after the accelerator is off.

FIG. 5 is a timing chart illustrating the operation when the required motor torque Tm is calculated with the required engine torque Te as 0 during the period ΔT after the accelerator is off.

FIG. 6 is a timing chart illustrating the operation of the second embodiment in which the regenerative braking force of the motor generator is gradually reduced immediately after the start of fuel cutting.

[Explanation of symbols]

13 ... Engine, 14 ... Motor generator (regenerative braking means), 24 ... Exhaust purification catalyst, 45 ... Axle, 57 ... Accelerator sensor (deceleration detection means), 58 ... Vehicle speed sensor (Deceleration detection means), 61 ... Hybrid ECU (fuel supply stop means, deceleration control means), 62 ... Engine ECU (fuel supply stop means), α ... predetermined time, ΔT ... period.