Vehicle drive unit

Abstract

To provide a vehicle drive unit which improves rigidity of a connection between an engine and a transaxle.SOLUTION: A drive unit 50 comprises: a first case 102 which is partitioned into two sections to house a crank shaft of an engine 12, a damper 54, a power split mechanism 56, a connecting gear group 58, a differential gear 20, an electric motor MG1, and an electric motor MG2; and a second case 104 which is fixed to each partitioned section of the first case 102 which is partitioned into two sections so as to close openings on a side of the engine 12 and on an opposite side of the first case 102. That is, since the crank shaft of the engine 12 and a power transmission component integrated within a transaxle 52 are housed in the cases unified in a connection direction, design flexibility of the case is improved, which in turn allows for a selection of a structure with improved desirability. Therefore, the vehicle drive unit can enhance the rigidity of the connection between the engine 12 and the transaxle 52.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a drive unit mounted on a vehicle.

Background Art

[0002] Vehicles equipped with an engine, a transmission, and a transaxle case that houses a differential gear are well known. Also, in the fastening between the crankcase of the engine and the transaxle case, a technique for enhancing the rigidity of the transaxle is disclosed. For example, the case structure of the transaxle described in Patent Document 1 is such a technique.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in the connection between the engine and the transaxle, the structure in which the crankcase of the engine and the transaxle case are prepared separately and fastened has a structure in which the rigidity of the fastening portion is low in the first place. Therefore, in order to enhance the rigidity, it is necessary to add a countermeasure structure or add aftermarket parts such as a stiffener. Further, when the mass of the transaxle case increases due to the integration of mounting an inverter, a control unit, etc. on the transaxle case, if the rigidity of the fastening portion is low with respect to the force from the engine, there is a problem that noise and vibration deteriorate.

[0005] The present invention has been made against the background of the above circumstances, and an object thereof is to provide a drive unit for a vehicle that improves the rigidity of the connection between the engine and the transaxle.

Means for Solving the Problems

[0006] The gist of the present invention is a drive unit of a vehicle including (a) an engine, an automatic transmission, and a differential gear, wherein (b) the drive unit includes a two-part first case that houses power transmission components from the crankshaft of the engine to the differential gear, and a two-part second case that is fastened to the first case so as to close an opening on the side opposite to the engine side of the first case.

Advantages of the Invention

[0007] According to the present invention, the drive unit includes a two-part first case that houses power transmission components from the crankshaft of the engine to the differential gear, and a two-part second case that is fastened to the first case so as to close an opening on the side opposite to the engine side of the first case. As a result, since the crankshaft of the engine and the power transmission components incorporated in the transaxle are housed in a case integrated in the connection direction, it is not necessary to add aftermarket parts to improve the rigidity of the connection between the engine and the transaxle. Compared with a structure in which the crankcase of the engine and the transaxle case are separate bodies, the degree of freedom in case design is improved, and a drive unit for a vehicle that can select a more desirable structure can be provided.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Embodiments for Carrying Out the Invention

[0009] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following embodiments, the drawings are appropriately simplified or deformed, and the dimensional ratios, shapes, etc. of each part are not necessarily drawn accurately.

Embodiment

[0010] In FIG. 1, the vehicle 10 is a hybrid vehicle including a drive unit 50 and wheels 14.

[0011] The drive unit 50 includes an engine 12 and a transaxle 52 incorporating an electric motor MG1 and an electric motor MG2, and power is transmitted from the drive unit 50 to the wheels 14 via a drive shaft 22.

[0012] The engine 12 is controlled by an engine control unit 40 including a throttle actuator, a fuel injection device, an ignition device, etc. provided in the vehicle 10 by an electronic control unit 70 described later, and the output torque of the engine 12 is controlled.

[0013] The transaxle 52 has the power of the engine 12 connected by a crankshaft 16, and includes a damper 54, a power split mechanism 56, an electric motor MG1, an electric motor MG2, an inverter 60, an inverter 62, a differential gear 20, a connection gear group 58, a transaxle case 90, etc., and is a unit constituting a known hybrid vehicle having a mechanism as an electric automatic transmission.

[0014] Further, the vehicle 10 is provided with a battery 64 as a power source for operating the electric motor MG1 and the electric motor MG2, and is connected to the inverter 60 and the inverter 62.

[0015] The motor MG1 is a so-called motor generator. The inverter 60 converts the DC power from the battery 64 into AC power and supplies it to the motor MG1, or converts the AC power generated by the motor MG1 into DC power and supplies it to the battery 64, and performs control such as this. The motor MG2 and the inverter 62 each have the same functions as the motor MG1 and the inverter 60, and their descriptions are omitted.

[0016] The vehicle 10 includes an electronic control unit 70 as a controller of the vehicle 10, and is configured to include a so-called microcomputer. Various signals based on detection values by various sensors etc. (for example, wheel speed sensor 80, accelerator opening sensor 82, MG1 rotational speed sensor 86, MG2 rotational speed sensor 88, etc.) provided in the vehicle 10 (for example, signals such as the wheel speed Nw which is the rotational speed of the wheel 14, the accelerator opening θa which is the accelerator operation amount representing the magnitude of the driver's acceleration operation, the MG1 rotational speed Nm1, the MG2 rotational speed Nm2, etc.) are each supplied. Also, the vehicle speed V is acquired from the wheel speed Nw of the wheel 14.

[0017] From the electronic control unit 70, various command signals (for example, engine control command signal Se, MG1 control command signal Sm1 for controlling the torque of the motor MG1, MG2 control command signal Sm2 for controlling the torque of the motor MG2, etc.) are each output to each device (for example, engine control unit 40, inverter 60, inverter 62, etc.) provided in the vehicle 10.

[0018] The electronic control unit 70 calculates the required driving torque Tr for the vehicle 10 by the driver, for example, by applying the accelerator opening θa and the vehicle speed V to a predetermined driving requirement amount map. The electronic control unit 70 outputs the engine control command signal Se to the engine control unit 40, the MG1 control command signal Sm1 to the inverter 60, and the MG2 control command signal Sm2 to the inverter 62 so that the driving torques respectively output from the engine 12, the motor MG1, and the motor MG2 realize the required driving torque Tr.

[0019] FIG. 2 is a schematic diagram for explaining a configuration example of the drive unit 50, where FIG. 2(a) shows a conventional example and FIG. 2(b) shows an embodiment to which the present invention is applied.

[0020] In the conventional example of FIG. 2(a), the transaxle case 90 of the transaxle 52 includes a housing 90a, a case body 90b, and a rear cover 90c. The housing 90a and the case body 90b are integrally fastened by a fastener such as a bolt so that the rightward-opening portion of the housing 90a on the paper surface and the leftward-opening portion of the case body 90b on the paper surface are combined. The case body 90b and the rear cover 90c are integrally fastened by a fastener so as to close the rightward-opening portion of the case body 90b on the paper surface with the rear cover 90c. By fastening the housing 90a to the crankcase 30 that forms the engine crank chamber Re of the engine 12 with a fastener, the engine 12 and the transaxle 52 are connected.

[0021] The case body 90b is a case configured to include a partition wall 90b1 that partitions a gear chamber Rg for housing a damper 54, a power split mechanism 56, a connecting gear group 58, a differential gear 20, etc., and a motor chamber Rm for housing an electric motor MG1 and an electric motor MG2. In the transaxle case 90, the gear chamber Rg is formed by the joining of the housing 90a and the case body 90b, and the motor chamber Rm is formed by the joining of the case body 90b and the rear cover 90c. Also, for example, an inverter 60 is mounted on the upper surface of the motor chamber Rm, and an inverter 62 is mounted on the side surface opposite to the engine 12.

[0022] In the conventional example, the crankcase 30 and the transaxle case 90 are separate bodies. Since the structure that fastens the two to connect the engine 12 and the transaxle 52 inherently has low rigidity at the fastening part, in order to increase the rigidity, it is necessary to add a countermeasure structure or add aftermarket parts such as a stiffener. Also, when the mass of the transaxle case 90 increases due to the integrated mounting of the inverter 60, inverter 62, etc. on the transaxle case 90, there is a problem that noise and vibration deteriorate when the rigidity of the fastening part is low against the force from the engine 12.

[0023] In the embodiment of Fig. 2(b), the crankcase 30 and the transaxle case 90, which were separate bodies in the conventional example, are integrated in the connecting direction and changed to a drive unit case 100 divided into two parts. The drive unit case 100 includes a first case 102 divided into two parts, a second case 104, and a center support 106. The first case also includes an upper case 102a and a lower case 102b. When the upper case 102a and the lower case 102b divided into two parts are connected by a fastener, an engine crank chamber Re is formed, and at the same time, a transaxle space for the gear chamber Rg and the motor chamber Rm is formed to the right in the paper plane of the engine crank chamber Re. The center support 106 is arranged in the middle of the transaxle space, and when the center support 106 is integrally connected to the upper case 102a and the lower case 102b by a fastener, a gear chamber Rg that houses the damper 54, the power split mechanism 56, the connecting gear group 58, the differential gear 20, etc., and a motor chamber Rm that houses the motor MG1 and the motor MG2 are formed. Also, the center support 106 also performs functions such as fixing the bearings of the gears of the unit mounted in the gear chamber Rg, the motor MG1, and the motor MG2. The second case 104 is integrally fastened by a fastener so as to close the opened part on the side opposite to the engine 12 of the upper case 102a and the lower case 102b divided into two parts. Also, as in the conventional example, for example, the inverter 60 is mounted on the upper surface of the motor chamber Rm, and the inverter 62 is mounted on the side surface opposite to the engine 12.

[0024] As described above, according to this embodiment, the drive unit 50 includes a two-part first case 102 that houses the crankshaft of the engine 12, the damper 54, the power split mechanism 56, the connecting gear group 58, the differential gear 20, the motor MG1, and the motor MG2, and a two-part second case 104 that is fastened to the first case 102 so as to close the opening on the side opposite to the engine 12 side of the first case 102. That is, since the crankshaft of the engine 12 and the power transmission components incorporated in the transaxle 52 are housed in a case integrated in the connecting direction, it is not necessary to add aftermarket parts to improve the rigidity of the connection between the engine 12 and the transaxle 52. Compared with the structure in which the crankcase 30 and the transaxle case 90 of the conventional example are separate from each other, the degree of freedom in case design is improved, and a drive unit for a vehicle that can select a more desirable structure can be provided.

[0025] Next, another embodiment of the present invention will be described. In the following description, the same reference numerals are given to the parts common to the embodiments, and the description thereof will be omitted.

Embodiment

[0026] In FIG. 3(a), the vehicle 110 is an engine-driven vehicle equipped with an automatic transmission 160. This embodiment is an example in which the transaxle 52 for a hybrid vehicle in Embodiment 1 is changed to a transaxle 152 for an engine-driven vehicle including an automatic transmission 160 and a differential gear 20 and the like.

[0027] The vehicle 110 includes a drive unit 150 and wheels 14. The drive unit 150 includes an engine 12 and a transaxle 152, and power is transmitted from the drive unit 150 to the wheels 14 via a drive shaft 22.

[0028] The transaxle 152 has the power of the engine 12 connected by the crankshaft 16, and is equipped with a torque converter 154, a forward and reverse switching device 156, an automatic transmission 160, a reduction gear 158, a differential gear 20, etc., which are well-known units. The automatic transmission 160 is composed of, for example, a planetary gear type stepped transmission or a belt type continuously variable transmission.

[0029] In addition, the vehicle 110 is equipped with a hydraulic control circuit 162. The hydraulic control circuit 162 controls the hydraulic pressure for controlling the gear ratio of the automatic transmission 160 and the hydraulic pressure for controlling the forward and reverse switching of the forward and reverse switching device 156.

[0030] The control function and control system of the electronic control device 70 are only different from those in the first embodiment in terms of the control of driving. In the first embodiment, the control was for the engine 12, the motor 1, and the motor 2, but in this embodiment, the control is for the engine 12, the automatic transmission 160, and the forward and reverse switching device 156. The electronic control device 70 outputs an engine control command signal Se to the engine control device 40, a shift control hydraulic pressure command signal Scvt for commanding the control hydraulic pressure of the automatic transmission 160, a forward and reverse control command signal Sc for controlling the operation of the forward and reverse switching device 156, etc. in response to the driving request of the vehicle 10 by the driver. Since the rest is the same as in the first embodiment, the description is omitted.

[0031] Figure 3(b) is a schematic diagram for explaining a configuration example of the drive unit 150 of this embodiment.

[0032] The drive unit case 200 has the same configuration as that of the first embodiment, and includes a two-part first case 202, a second case 204, and a center support 206. The first case further includes an upper case 202a and a lower case 202b. Similar to the first embodiment, when the upper case 202a, the lower case 202b, and the center support 206 are fastened, an engine crank chamber Re, a torque converter 154, a forward / reverse switching device 156, a reduction gear 158, a differential gear 20, etc. are accommodated in a gear chamber Rg, and an automatic transmission 160 is accommodated in a transmission chamber Rt. Further, the center support 206 also fixes the gears of the units mounted in the gear chamber Rg and the bearings of the automatic transmission 160. The second case 204 is integrally fastened by a fastener so as to close the opened portion on the side opposite to the engine 12 of the two-part upper case 202a and lower case 202b.

[0033] As described above, according to the present embodiment, the drive unit 150 includes a two-part first case 202 that houses the crankshaft of the engine 12, a torque converter 154, a forward / reverse switching device 156, an automatic transmission 160, a reduction gear 158, and a differential gear 20, and a two-part second case 204 that is fastened to the first case 202 so as to close the opening on the side opposite to the engine 12 side of the first case 202. That is, since the crankshaft of the engine 12 and the power transmission components built in the transaxle 152 are housed in a case integrated in the connecting direction, it is not necessary to add aftermarket parts to improve the rigidity of the connection between the engine 12 and the transaxle 152. Compared with a structure in which the crankcase of the engine 12 and the transaxle case are separate bodies, the degree of freedom in case design is improved, and a drive unit for a vehicle that can select a more desirable structure can be provided.

[0034] The embodiments of the present invention have been described in detail with reference to the drawings, but they are merely one embodiment, and the present invention can be implemented in various modified and improved forms based on the knowledge of those skilled in the art.

Explanation of Reference Numerals

[0035] 10: Vehicle 12: Engine 14: Wheel 20: Differential gear 50, 150: Drive unit 102, 202: First case 104, 204: Second case 160: Automatic transmission

Claims

【Claim 1】 A drive unit for a vehicle, comprising an engine, an automatic transmission, and a differential gear, wherein the drive unit includes a first case divided into two parts for accommodating power transmission components from the crankshaft of the engine to the differential gear; and a second case divided into two parts, each fastened to the first case so as to close the opening on the side of the first case opposite to the engine. A drive unit for a vehicle, characterized by the above.

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