Series and parallel hybrid drive with two primary drive units

The invention relates to a hybrid drive according to the preamble of claim. 1

When hybrid is a combination of different drive principles or different energy sources for a drive task within an application, such as a vehicle, respectively.

Depending on the arrangement and the mechanical connection of the drive machine distinguishes between serial and parallel hybrid drive Hyb-ridantrieb. In a serial-Hybrid the entire power of the internal combustion engine via an electrical generator or a hydraulic pump in electric / hydraulic energy is converted, and the drive of the vehicle is carried out exclusively by an electric or hydraulic motor. The disadvantage here is that the mechanical power is first converted into electrical / hydraulic power and then into mechanical power, which the serial hybrid engine at the high end, for example, full load, has a poor efficiency again.

In a parallel hybrid, two prime movers, such as an electric motor or hydraulic motor and an internal combustion engine, with a final drive in conjunction so that the vehicle in question with appropriate design and arrangement of the powertrain, separately from the electric motor or hydraulic motor, separately from the internal combustion engine, or can be driven by both prime movers. This solution has the drawback that the electric motor or hydraulic motor is dependent on the energy of the internal combustion engine and, for example, a pure electric motor operation is possible only when the power generated by the internal combustion engine. While it can also be used vehicle braking energy to charge the battery for the electric motor, but their capacity is not sufficient for a longer operation of a vehicle.

In the <patcit id="pcit0001" dnum="US5495912A"><text>US 5495912</text></patcit> is a parallel hybrid disclosed in which an internal combustion engine transmits power to a drive shaft to which a hydraulic unit is connected, which can be operated as a hydraulic pump or hydraulic motor and a drive unit (gears, wheels, etc.) is driven a vehicle. The hydraulic unit is a hydraulic accumulator operatively connected to the power proposed to the hydraulic motor or can absorb energy from the hydraulic pump. To charge the hydraulic accumulator is either the vehicle braking energy and thus ind ust uses the internal combustion engine to be supplied by a part of the acceleration energy of braking, or it is used directly, the internal combustion engine for driving the hydraulic pump. In addition to the internal combustion engine, a further internal combustion engine can be switched to the drive shaft in order to increase the performance of the parallel hybrid. The disadvantages of the solution<patcit id="pcit0002" dnum="US5495912A"><text>US 5495912</text></patcit> are those described above, therefore, the electric motor can not be operated independently of the internal combustion engine connected to the drive shaft.

The object of the present invention is to provide a hybrid drive, which are versatile and has high efficiency.

This object is achieved by a hybrid drive which has two primary aggregates and a hydraulic or electric machine, one of the primary aggregates and the hydraulic or electric machine are operatively connected with a drive shaft, wherein the hydraulic or electric machine with one of the primary aggregates a serial hybrid drive and with the other prime mover constituting a parallel hybrid drive. The combination of a serial hydride with a parallel hybrid drive offers the advantage that the hydraulic or electric motor can be operated largely independently of the operatively connected to the drive shaft prime mover. In exemplary off this prime mover of hydraulic or electric motor can be operated in full function on, as this is supplied by the other prime mover with energy.

Preferably, the primary units are of different size in terms of performance and space, whereby the hybrid drive can be flexibly adapted to the desired operational and performance of a vehicle:

Preferably a large, with respect to the installation space and power, the primary unit that forms a parallel hybrid drive with the hydraulic or electric machine, an internal combustion engine. This can provide a high drive power available and move a vehicle very efficiently and with a high efficiency at high speeds or accelerations.

In a preferred embodiment, the smaller primary unit, which forms a serial hybrid drive with hydraulic or electric machine, a free-piston engine. This is very efficient in the low power range and may the hydraulic or electric machine supply enough energy, so this example, the "Stop and Go" operation of the vehicle is largely independent of the other prime mover (internal combustion engine) can be operated.

The free-piston engine, for example, low-pressure side via a low-pressure line with a low-pressure accumulator and high-pressure side connected via a high pressure line with a high-pressure accumulator. The hydraulic unit is preferably connected to the high-pressure and low-pressure line and can promote the high-pressure accumulator and is provided as a hydraulic motor from the high-pressure accumulator with pressure medium and this proposed to the low-pressure accumulator as a hydraulic pump pressure medium from the low-pressure accumulator.

The hydraulic machine is advantageously via a clutch and a mechanical transmission connected to the drive shaft. This allows them to be toggled to by one or disengage from the vehicle drive or.

The internal combustion engine is a clutch and a gear connected to the drive shaft and thus as the free-piston engine are toggled to the drive or.

The drive shaft is, for example, with a differential gear and a wheel drive arranged thereon in operative connection.

The drive shaft may either be driven by the internal combustion engine or by the hydraulic motor, or both. This enables a flexible power adjustment of the drive of the vehicle to different operating conditions.

The hydraulic pump can advantageously be driven by wheel drive via the differential gear and the drive shaft, which makes it possible to convert braking energy into hydraulic energy.

Other advantageous embodiments of the invention are subject matter of further subclaims.

In the following, a preferred embodiment of the invention will be explained in detail with reference to a single drawing.

This shows a schematic representation of a hybrid drive according to an embodiment.

The figure shows a schematic view of the arrangement of a hybrid drive 1 with two primary units 2, 4, which have different power and space, and a hydraulic machine 6. This and the prime mover 2, which serves as the internal combustion engine 2 (abbreviated in the following with VKM 2) , is carried out, for example, as diesel or gasoline engine, linked to a drive shaft 8 in operative connection. The VKM 2 is a transmission case 10 and a clutch 12 connected to the drive shaft 8 and is switched on and off via the coupling 12 to the drive shaft. 8 The transmission 10 is designed with multiple gear ratios between the VKM 2 and the driveshaft. 8 Also with a gear 14, however, which has a fixed transmission ratio, and a clutch 16, the hydraulic machine 6 is connected to the drive shaft 8 and the coupling 16 to this to-and switched away. The hydraulic machine 6 is connected via a high-pressure connection 18 at a high pressure line 20 and a low pressure port 22 to a low pressure line 24th The high- and low-pressure line 20, 24 are in turn connected to the other prime mover 4, in the form of a free-piston engine 4 (abbreviated in the following with FKM 4) is formed. The high pressure line 20 is at an outlet port 25 and the low pressure line 24 is connected to an inlet port 26 of the FKM 4th A high-pressure accumulator 27 is attached to the high pressure line 20 and thus is in operative engagement with the hydraulic machine 6 and the FKM 4. low-pressure side, a low-pressure accumulator 28 is connected to the low pressure line 24 and the fourth forms the hydraulic unit 6 in connection with the hydraulic machine 6 and the FKM together with FKM 4 a serial hybrid drive and the VKM 2 a parallel hybrid drive. The drive shaft 8 is connected with a differential gear 30 to which a wheel-drive shaft 32 is connected, in turn, is connected to wheels 34 of a vehicle, not shown.

In the following, the structure of the FKM 4 is explained in more detail. This has a motor housing 36, through which a combustion cylinder 38 and a hydraulic cylinder 40 are limited. In a cylinder bore of the combustion cylinder 38. Piston 42 is guided via which the cylinder bore into a combustion chamber 43 and an inlet space is divided 46th The combustion chamber 43 has an outlet 44 and an air inlet 45 which is connected via the inlet chamber 46 with the surroundings, an towards the latter closing check valve 47th The injection of the fuel into the combustion chamber 38 via an injection valve 48 in the cylinder head of the combustion cylinder 38. Piston 42 carries a piston rod 50. This piston rod 20 emerges in an axial bore of the hydraulic cylinder 40 and forms opposite to the side of the engine piston 42 of a hydraulic piston 52 on , The hydraulic piston 52, the axial bore is divided into a cylinder chamber 54 and an annulus 56th The annular space 56 is connected to the cylinder chamber 54 via a formed in the hydraulic piston 52 check valve 58 which opens towards the cylinder space 54, connectable. In the annulus 56, pressure medium from the low pressure accumulator 28 and the low pressure line 24 via a check valve 60 which opens to the annular chamber 56 towards. Another low-pressure accumulator 61 is connected just before the non-return valve 60, outside of the annular space 56, with the low pressure line 24th At the cylinder space 54, a 2/2-way valve 62 is connected that connects to a tank T or is closed. Furthermore, with the cylinder chamber 54 a working port of a logic element 64 in fluid communication, the other working connection with a high-pressure accumulator 66 and the high pressure line 20 is connected. At a control terminal of the logic element 64 is a 3/2-way valve 68 is in operative connection, which switches a connection to the tank T or to the high pressure line twentieth

In operation, the FKM 4 is the combustion energy generated in the combustion chamber 43; converted via the axial movement of the engine piston 42, the piston rod 50 and the hydraulic piston 52 into hydraulic energy by pressure medium, which is conveyed via the pressure line 24 into the cylinder chamber 54 from the low pressure accumulator 28, is compressed therein and then through the high pressure line 20 for further high-pressure accumulator 27 passes. FKM 4 is controlled by a control unit 70. The FKM 4 can be highly variable controlled and operated. In addition, the FKM makes 4 very compact build and is characterized by great simplicity and a high power-to-weight ratio. For additional information about the functioning and structure of the FKM 4 is an example to the publication<patcit id="pcit0003" dnum="DE10026728A1"><text>DE 100 26 728 A1</text></patcit> referenced.

The hydraulic machine 6 can be operated as a hydraulic motor or hydraulic pump. If the hydraulic machine 6 is operated as a hydraulic motor 6, this is powered by the high-pressure accumulator 27, the high pressure line 20 and the high pressure port 18 with pressure medium and is driven and the pressure medium is then passed through the low pressure port 22 into the low-pressure accumulator 28th In the engaged clutch 16, the hydraulic motor drives 6 through the transmission 14, the drive shaft 8, which in turn, via the differential gear 30 and the wheel drive 32, the wheels 34 drives. A use of the hydraulic machine 6 as a hydraulic pump 6 takes place when the wheels 34, such as during braking of the vehicle, on the wheel drive 32 and the differential gear 30 to drive the drive shaft 8 and this in turn via the gear 14 and the engaged clutch 16, the hydraulic pump 6. In this case, is the VKM 2 disengaged. The hydraulic pump 6 thereby promotes pressure medium from the low pressure accumulator 28 to the high-pressure accumulator 27 via the pressure lines 20, 24, so that it is charged. To the hydraulic pump 6 thus, the braking energy generated when braking is converted into hydraulic energy and stored in high-pressure accumulator 26th

The VKM 2 drives at the engaged clutch 12 via the transmission 10 to the drive shaft 8, which then transmits the torque to the wheels 34th

The hybrid drive system 1 can be used widely. At high speeds and power requirements of the vehicle that is driven by the ICE 2, which at full load has a very high efficiency. Should the vehicle be operated with maximum performance of the hybrid drive 1, so in addition, the hydraulic motor 6 is switched in and the vehicle is driven by two motors 2, 6 simultaneously in the "boost" mode. The hydraulic motor 6 is powered by the hydraulic accumulator 26 with energy which is in turn charged by the FKM 4th

If a "Stop to Go" use of the vehicle, which consists of short acceleration phase with subsequent deceleration phase, for example as in refuse collection vehicles or cars in city traffic, it will be connected to the hydraulic serial hybrid drive consisting of the hydraulic machine 6 and the FKM 4, driven. The vehicle is accelerated by the hydraulic machine 6 in the form of the hydraulic motor 6 and when decelerating and braking, the hydraulic machine 6 is used as a hydraulic pump. 6 The recovery of the braking energy of the vehicle to the additional energy required for the hydraulic motor 6 limited solely to the compensation of losses caused by, for example, driving resistance (air resistance, rolling resistance) and conversion losses in the drive train. This low energy consumption is then covered by the FKM 4, by this the high-pressure accumulator charging in accumulator operation 27th In this field of use of the vehicle, the FKM 4 is highly efficient with a high efficiency, whereby the fuel economy and CO₂Emissions are significantly reduced.

The VKM 2 and the hydraulic machine 6 can be switched on and off by the drive train 8 as drive units in all areas independently and arbitrarily, whereby a high degree of flexibility of the hybrid system 1 is possible and it can be operated with the best efficiency and optimally adapted power.

The invention is not limited to the above-explained embodiment. It is conceivable to operate the serial hybrid rather than hydraulic, electric. The high-pressure accumulator 27 would then be performed as a battery, and the hydraulic actuator 6 as an electric drive, which is used as a generator and motor.

The invention discloses a hybrid drive, with at least two primary aggregates and a hydraulic or electric engine, a prime mover and the hydraulic or electric machine are connected to a drive train operatively connected and the hydraulic or electric machine with this prime mover a parallel hybrid drive and the other prime mover serial hybrid drive forms.