Method and arrangement for selecting a starting gear and a vehicle comprising this arrangement

FIELD OF THE TECHNIQUE

The invention relates to a method and a device for selecting a starting speed 5 when a vehicle is maneuvered at low speed while a body device is being used in the vehicle.

The invention also relates to a computer program that causes the execution of said method with a computer.

PREVIOUS TECHNIQUE 10

Currently, "Automatic Mechanical Transmissions" or AMTs are increasingly common in heavy duty vehicles. In order to determine the speed selection strategy for vehicles with AMT, a calculation or estimate of the current road resistance is generally performed. The current road resistance is determined based on input signals from a number of detectors, after which an electronic control unit determines an appropriate 15 speed selection strategy.

For the selection of a starting speed, this generally means that the control unit only pays attention to the weight of the vehicle and the gradient of the ground surface, thereby selecting a starting speed that offers starting characteristics optimal. This usually means that a relatively high starting speed is selected and that the transmission goes up by 20 speed as soon as the speed selection strategy allows. The intervention is that the vehicle is able to start and reach a cruising speed as quickly as possible.

This speed selection is not ideal on all occasions. For example, in the lifting of goods from a platform, in the ordering referred to with the lifting or in low-speed maneuvers at the same time that a body device is being used on the vehicle, a starting speed selected in the previous way It may be completely inappropriate.

Through EP 1 103 742, for example, an AMT system can be seen in which the driver can manually select a preselected start speed as long as this selection is accepted by the transmission control unit. If a power take-off is activated, said control unit 30 will switch temporarily from automatic to manual speed mode. This system calls the driver to make certain adjustments with respect to the starting speed. In the case of a driver change, problems can be increased if a previous driver has preselected a starting speed that is not suitable for the maneuver he has to perform.

The object of the invention is therefore to solve the aforementioned problems by offering a method in which the transmission control unit detects that a power take-off is active when starting from stationary or almost stationary, a starting speed preprogrammed that is selected and maintained until at least one predetermined condition has been met, for example that the power take-off is deactivated. This happens without the automatic speed change mode of the vehicle being disengaged and without the need for driver intervention. 40

DESCRIPTION OF THE INVENTION

The above objects are achieved by a method for selecting a starting speed, the characteristics of which can be seen from claim 1 of the patent, with a device that is claimed in claim 8 of the patent, and with a vehicle comprising said device as claimed in claim 14. 45

According to a preferred embodiment, the invention relates to a method for selecting a starting speed for a vehicle comprising an engine, an AMT transmission and a power take-off for maneuvering at least one body device in the vehicle. The method comprises the following stages:

<dl>&lt;dt /&gt;<dd>- Creation of a first signal after activation of the power take-off for the maneuverability of at least 50 a body device mounted on the vehicle; </dd></dl>

<dl>&lt;dt /&gt;<dd>- Control of the transmission speed selection strategy for the selection of a predetermined starting streak depending on at least said first signal; </dd></dl>

<dl>&lt;dt /&gt;<dd>- Maintenance of the default starting speed for so long that at least one predetermined condition is met. 55</dd></dl>

Said condition for maintaining the predetermined starting speed may be constituted by a number of different parameters. A condition may be that a power take-off, in the form of a compressor, hydraulic pump or the like, is activated.

Other conditions may be that the vehicle travel exceeds a predetermined distance, or that the vehicle speed exceeds a certain speed for a predetermined period of time. Suitable distances and / or speeds are selected with respect to the main field of application of the vehicle. This may be relevant for certain types of vehicles, such as cement mixers, in which a power take-off can be activated either when it starts or during the journey of a vehicle with a full load.

According to another embodiment, the predetermined starting speed is preferably, but not necessarily, the lowest transmission speed. The selection of a starting speed can be pre-programmed with a selection recommended at the factory or at the user's discretion. The selection of the starting speed can, of course, be subsequently altered if, for example, the field of application of the vehicle is changed.

The selection of a starting speed by the transmission is preferably controlled independently of the measured and particular weight of the vehicle. It is possible, however, to program the transmission control unit 15 to select a starting speed from a table dependent on the weight-train-route stored in the memory of the control unit.

According to another embodiment, the control unit selects an automatic transmission mode with a speed selection strategy comprising the predetermined starting speed. Consequently, the driver does not have to intervene to select a starting speed, which would be the case if the control unit were conventionally to select a manual transmission mode.

The invention also comprises a device for selecting a starting speed for a vehicle comprising an engine, an AMT type transmission and an automated mechanical transmission and a power take-off for the maneuverability of at least one body device in the vehicle. In addition, the device comprises at least one detector to generate a first signal after activation of the force take-off to maneuver at least one body device mounted in the vehicle and an electronic control unit to control the speed selection strategy of the transmission depending on at least said first signal, maintaining a predetermined starting speed provided that at least one predetermined condition is met.

The electronic control unit is preferably installed to maintain the predetermined starting speed for as long as the power take-off is activated.

According to an alternative embodiment, the predetermined starting speed is maintained until the vehicle travel has exceeded a predetermined distance, or until the vehicle speed has exceeded a certain speed for a predetermined period of time. This allows the electronic control unit to select another speed even though the power take-off is activated. 35 According to another embodiment, the device can be controlled so that the shift lever is allowed if a first power take-off is active, but it is prohibited if a second power take-off is active.

The predetermined starting speed is preferably, but not necessarily, the lowest transmission speed. Alternatively, the starting speed can be selected from a table dependent on the weight-train-route stored in the electronic control unit. 40

The invention also relates to a vehicle provided with a device according to the above, whose vehicle comprises an engine, an AMT type transmission and an automated mechanical transmission and a power take-off for the maneuverability of at least one body device in the vehicle. As described above, the device comprises at least one detector for generating a first signal after activation of the power take-off to maneuver at least one body device mounted on the vehicle and an electronic control unit for controlling the vehicle's strategy. transmission speed selection depending on at least said first signal, maintaining a predetermined starting speed provided that at least one predetermined condition is met.

The invention thus allows an automatic transmission mode with a speed selection strategy comprising a predetermined starting speed. Therefore, the driver does not need to intervene to select a starting speed, which would be the case if the control unit were conventionally to select a manual transmission mode.

DESCRIPTION OF THE FIGURES

The invention will be described in greater detail below using an illustrative embodiment with reference to the attached schematic figures, in which:

Figure 1 shows a schematic illustration of an automatic device for selecting a starting speed according to the invention;

Figure 2 shows a schematic illustration of a flow chart for controlling a device according to the invention;

Figure 3 shows a schematic illustration of a flow chart for controlling an alternative device according to the invention.

PREFERRED EMBODIMENTS 5

Figure 1 shows a schematic illustration of an automatic device for selecting a starting speed according to the invention. The device comprises a central electronic control unit (ECU) 1, which is connected to a motor control unit 2 for a motor 3 and a transmission control unit 4 for an automated transmission (AMT) 5. The engine control unit 2 receives signals from a number of detectors (not shown) of engine speed, torque, 10 speed, weight-train-route, road gradient, etc. The central electronic control unit 1 receives signals from an accelerator pedal 6 controlled by the driver, a speed selector 7, and data from the motor control unit 2 comprising a number of operating parameters related to the engine. Based on these received signals, the central electronic control unit 1 selects a suitable speed selection strategy from a number of strategies 15 stored in a memory integrated in the control unit 1. Signals related to the speed selection are then sent to the transmission control unit 4 of the automated transmission 5, which performs a shift lever at the requested speed. At the same time, signals are sent to the motor control unit 2, requesting the desired motor speed. Transmissions of this type are commonly known previously under EP 1 103 742, US 5 816 100, US 5 390 561, US 4 754 665 20 and US 4 735 109, for example, and will not be described in detail.

A signal representing a speed selection is also sent to a display 8, which provides the driver with confirmation of the speed that is currently selected.

Apart from these previous signals, the central electronic control unit 1 receives other signals from a power take-off (PTO) 9 whenever it is activated. The power take-off may be constituted by a compressor, hydraulic pump or the like and is used to drive a body unit in the vehicle. The power take-off can also be mounted for direct driving with the vehicle's engine.

Figure 2 shows a schematic illustration of a flow chart for controlling a device according to the invention. Control S1 is started when the driver activates the speed selector S2 for a stationary vehicle. The central electronic control unit, hereinafter referred to as 30 the vehicle ECU, checks in this case if a power take-off is active S3. If this is not the case, the vehicle ECU selects an appropriate starting speed based on the speed selection strategy based on the vehicle's weight-train-route and the particular gradient of the road. If a power take-off is active, a mode called PTO is instead activated, in which the vehicle ECU selects and blocks the transmission from a predetermined starting speed. Then, the vehicle ECU 35 will continuously monitor whether the particular power take-off is active S6 and will maintain the selected starting speed S7 until the power take-off is deactivated. When this happens, said PTO mode is deactivated S8 and the vehicle ECU reselects a G4 speed based on a speed selection strategy based on the weight-train-route of the vehicle, the gradient of the road and the requested torque by the driver The vehicle start regulation is concluded S9. 40

Figure 3 shows a schematic illustration of a flow chart for controlling an alternative device according to the invention. The vehicle is initially regulated in the same manner as described in Figure 2. After a PTO mode has been activated S5, the vehicle ECU will begin monitoring the particular power take-off S6 and maintain the selected starting speed S7 . Monitoring, however, implies an additional stage, in which the vehicle ECU checks whether another condition S10 is met. As long as this condition is not met, the monitoring of the power take-off continues. If, on the other hand, the condition proves to have been fulfilled, said PTO mode is concluded S8 and the vehicle ECU reselects a speed S4 according to Figure 2 above. Examples of such a condition may be that the movement of the vehicle has exceeded a predetermined distance, or that the vehicle speed has exceeded a certain speed for a predetermined period of time. fifty

The invention is not limited to the foregoing and to the illustrative embodiments shown in the drawings, but may be modified within the scope of the following patent claims.