Transaxle

Abstract

To provide a transaxle which can achieve reduction of vibration and noise and effectively protect an electric power device while achieving reduction of the number of components and downsizing.SOLUTION: A transaxle of the disclosure has an electric motor, a gear mechanism connected to the electric motor and an engine, and a case which houses the electric motor and the gear mechanism and is mounted on a vehicle. A case of the transaxle includes: a first case which has a height lower than that of the engine, is fixed to the engine, and houses the gear mechanism; a second case which has a height lower than that of the engine and higher than that of the first case and houses the electric motor and an electric power device for driving the electric motor; and a stiffener which is fixed at one end to the first case and fixed at the other end to a portion of the second case which protrudes farther than the first case in a height direction.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to a transaxle installed in a vehicle. [Background technology]

[0002] Conventionally, a hybrid vehicle including an engine, a transaxle including two motors, and a power converter that converts power from a power source into drive power for the motors is known (see, for example, Patent Document 1). In this hybrid vehicle, the engine and the transaxle are connected so as to be adjacent to each other in the vehicle width direction. The power converter is supported above the transaxle with a gap provided via a front bracket attached to the front surface and a rear bracket attached to the rear surface. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-079765 Summary of the Invention [Problem to be solved by the invention]

[0004] If the above-mentioned power converter were housed inside the transaxle case, the number of parts would be reduced by omitting brackets, and the entire transaxle, including the power converter, would be made smaller. However, in a transaxle in which the power converter is housed inside the case, the weight of the power converter would be added, increasing the weight of the entire transaxle, and the resonance frequency of the transaxle and the housing of the power converter in the case would decrease. For this reason, there is a risk that the entire transaxle will resonate due to the forcing force (vibration) from the engine, resulting in increased vibration and noise, or that vibration (high-frequency vibration) from the engine will adversely affect the components of the power converter inside the case.

[0005] Therefore, a primary object of the present disclosure is to provide a transaxle that can reduce vibration and noise while reducing the number of parts and size, and can provide good protection for electric equipment. [Means for solving the problem]

[0006] The transaxle disclosed herein is a transaxle mounted on a vehicle and having an electric motor, a gear mechanism connected to the electric motor and an engine, and a case housing the electric motor and the gear mechanism, wherein the case includes a first case that is lower than the engine, fixed to the engine and housing the gear mechanism, a second case that is lower than the engine and taller than the first case and houses the electric motor and power equipment for driving the electric motor, and a stiffener having one end fixed to the first case and the other end fixed to a portion of the second case that protrudes vertically above the first case.

[0007] In the transaxle of the present disclosure, brackets, bushes, and bolts for fixing the electric equipment to the case, a case for accommodating the electric equipment, and the like can be omitted, so that the number of parts can be reduced and the entire device can be made smaller. In addition, a stiffener is provided between the first case and a portion of the second case that protrudes in the height direction from the first case, and the second case 42 is supported by the first case via the stiffener. Furthermore, since the second case is made lower in height than the engine, the axial length of the stiffener can be shortened to reduce the moment applied to the stiffener from the second case. This makes it possible to effectively suppress the second case from vibrating toward or away from the engine and to effectively ensure the durability of the stiffener. In addition, since high-frequency vibrations from the engine are attenuated by the first case and the stiffener before being transmitted to the second case, the effect of vibrations on the electric equipment arranged in the second case can be further reduced. As a result, in the transaxle of the present disclosure, it is possible to reduce the number of parts and the size of the device, while reducing vibrations and noise and protecting the electric equipment. [Brief description of the drawings]

[0008] [Figure 1] 1 is a schematic configuration diagram of a vehicle including a transaxle according to the present disclosure. [Diagram 2] FIG. 1 is a schematic diagram showing a transaxle of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Next, an embodiment of the present disclosure will be described with reference to the drawings.

[0010] 1 is a schematic diagram showing a vehicle 1 including a transaxle 20 according to the present disclosure. The vehicle 1 shown in the figure is a front-wheel drive hybrid vehicle including an engine 10, a transaxle 20 including motor generators MG1 and MG2 and serving as a power transmission device both connected to the engine 10, and a battery (not shown) that exchanges electric power with the motor generators MG1 and MG2 of the transaxle 20 via an inverter (not shown) or the like. The engine 10 is an internal combustion engine that combusts a mixture of air and hydrocarbon fuel injected from an injector (not shown) in multiple combustion chambers and converts the reciprocating motion of pistons associated with the combustion of the mixture into the rotational motion of a crankshaft.

[0011] 1, in addition to motor generators MG1 and MG2, transaxle 20 includes planetary gear 30, differential gear 39, and case 40 that houses these elements. Motor generator MG1 (first electric motor) is a synchronous generator motor (three-phase AC motor) including a stator S1 and a rotor R1, and operates mainly as a generator that converts at least a part of the power from engine 10 operated under load into electric power. Motor generator MG2 (second electric motor) is a synchronous generator motor (three-phase AC motor) including a stator S2 and a rotor R2, and operates mainly as a motor that is driven by electric power from at least one of a battery and motor generator MG1 to generate drive torque.

[0012] The planetary gear 30 is a differential rotation mechanism including a sun gear (first rotating element) 31, a ring gear (second rotating element) 32, and a planetary carrier (third rotating element) 34 that rotatably supports a plurality of pinion gears 33. As shown in FIG. 1, the sun gear 31 is connected to a rotor R1 of the motor generator MG1 via a hollow rotor shaft RS. The planetary carrier 34 is fixed coaxially to a carrier shaft CS, and is connected to a crankshaft of the engine 10 via the carrier shaft CS and the damper mechanism 25. The ring gear 32 is integrated with a counter drive gear 35 as an output member, and the two rotate coaxially and integrally.

[0013] The counter drive gear 35 is connected to left and right wheels (drive wheels) W via a counter driven gear 36 meshing with the counter drive gear 35, a drive pinion gear (final drive gear) 37 rotating integrally with the counter driven gear 36, a differential ring gear 39r meshing with the drive pinion gear 37 and rotating integrally with a differential case of the differential gear 39, the differential gear 39, and a drive shaft DS. The gear mechanism of the transaxle 20, i.e., the planetary gear 30 and the gear train from the counter drive gear 35 to the differential gear 39, connects the engine 10 and the motor generator MG1 to each other, and transmits a portion of the output torque of the engine 10 as a power generation source to the drive shaft DS and the wheels W.

[0014] Further, a drive gear 38 is connected (fixed) to the rotor R2 of the motor generator MG2 via a motor shaft MS so as to rotate integrally therewith. The drive gear 38 has a smaller number of teeth than the counter driven gear 36, and meshes with the counter driven gear 36. As a result, the motor generator MG2 is connected to the left and right drive shafts DS and wheels W via the drive gear 38, the counter driven gear 36, the drive pinion gear 37, the differential ring gear 39r, and the differential gear 39. That is, the motor generator MG2 functions as a power generation source that outputs drive torque (drive force) to the drive shafts DS and wheels W, either alone or in cooperation with the engine 10, and also outputs regenerative braking torque when braking the vehicle 1.

[0015] The case 40 of the transaxle 20 includes a first case 41, a second case 42, and a cover (third case) 45. The first and second cases 41, 42, and the cover 45 are all cast products made of, for example, aluminum alloy or steel. As shown in Figs. 1 and 2, the first case 41 is fastened (joined) to the engine block (cylinder block) 110 of the engine 10 via a plurality of bolts so as to be adjacent to each other in the width direction of the vehicle 1. The second case 42 is fastened (joined) to the first case 41 via a plurality of bolts so as to be adjacent to each other in the width direction of the vehicle 1, and constitutes a case main body together with the first case 41. The cover 45 is fastened (joined) to the second case 42 via a plurality of bolts so as to cover an open end of the second case 42 on the opposite side to the first case 41 side.

[0016] In addition, the second case 42 has a partition wall 42w that divides the inside of the case 40 (case main body) into two. As a result, inside the case 40, a gear chamber Cg is defined on the engine 10 side of the partition wall 42w, and a motor chamber Cm is defined on the cover 45 side of the partition wall 42w. As shown in FIG. 1, the gear mechanism, i.e., the planetary gear 30 and the gear train from the counter drive gear 35 to the differential gear 39, are arranged in the gear chamber Cg. As shown in FIG. 1 and FIG. 2, the motor generators MG1, MG2 and the electric power device 50 connected to the motor generators MG1, MG2 and the battery are arranged in the motor chamber Cm.

[0017] The power devices 50 include a first inverter, a second inverter, a boost converter, a filter capacitor, a smoothing capacitor, a DC / DC converter, an electronic control device, etc. The first inverter drives a motor generator MG1, and the second inverter drives a motor generator MG2. The boost converter boosts the power from the battery and reduces the power from the motor generators MG1 and MG2. The DC / DC converter is connected to a power line connecting the battery and the boost converter, an auxiliary battery, and a plurality of auxiliary devices, and reduces the power on the battery and boost converter side to a target voltage and supplies it to the auxiliary battery and the auxiliary devices. The electronic control device includes a microcomputer, various drive circuits, etc., and controls the first and second inverters and the boost converter.

[0018] As shown in FIG. 2, the first case 41 is formed lower than the engine 10. The second case 42 is formed lower than the engine 10 and higher than the first case 41. In this embodiment, when the transaxle 20 is mounted on the vehicle body of the vehicle 1, the second case 42 protrudes upward (in the height direction) from the upper surface of the first case 41, and a core plate 42p fixed to the upper end of the second case 42 is located lower than at least the camshaft 111 of the engine 10, more specifically, the cam housing 112 that supports the camshaft 111 and is fixed to the engine block 110. The above-mentioned electric equipment 50 is accommodated in an upper portion 42u of the second case 42 that protrudes upward from the first case 41. In this embodiment, at least a part of the electric equipment 50 is attached to the core plate 42p, and the motor generators MG1 and MG2 are accommodated in a lower portion 42l of the second case 42 so as to be located below the electric equipment 50.

[0019] Furthermore, as shown in FIG. 2, a space is defined between the upper part of the engine 10 and the upper part 42u of the second case 42 in the width direction of the vehicle 1, and at least one stiffener (reinforcement material) 47 is disposed in the space. The stiffener 47 is, for example, a round bar with an outer diameter of about 10 mm, and has mounting parts with bolt holes at both ends. One end of the stiffener 47 is fixed to the upper part 42u of the first case 41 via a bolt so that the mounting part abuts against the upper surface of the first case 41. The other end of the stiffener 47 is fixed to the upper part 42u of the second case 42 via a bolt so that the mounting part abuts against a side surface of the upper part 42u that protrudes upward from the first case 41 of the second case 42. As a result, the stiffener 47 extends obliquely so as to be positioned upward from the first case 41 toward the second case 42 when the transaxle 20 is mounted on the vehicle body of the vehicle 1. As a structure for fixing stiffener 47 to first and second cases 41, 42, any structure may be adopted.

[0020] In the transaxle 20 configured as described above, it is possible to omit brackets, bushes, and bolts for fixing the electric power equipment 50 to the case 40, a case for housing the electric power equipment 50, and the like, and therefore the number of parts can be reduced and the overall device can be made smaller. On the other hand, the weight of the electric power equipment 50 is added, and the overall weight of the transaxle 20 increases, and the resonance frequency of the upper part 42u of the second case 42 housing (supporting) the transaxle and the electric power equipment 50 decreases. For this reason, in the transaxle 20, there is a risk that the upper part 42u of the second case 42, which protrudes upward from the first case 41, vibrates so as to approach or move away from the engine 10 due to resonance caused by a forcing force (vibration) from the engine 10 (see the two-dot chain line arrow in FIG. 2), but the stiffener 47 is provided between the upper surface of the first case 41 and the upper part 42u of the second case 42 as described above. As a result, the upper portion (protruding portion) 42u of the second case 42 is supported by the first case 41 via the stiffener 47, making it possible to effectively suppress the upper portion 42u from vibrating toward or away from the engine 10.

[0021] In addition, in the transaxle 20, the second case 42 is made low-profile so that the core plate 42p is located below the camshaft 111 and the cam housing 11 of the engine 10 when mounted on the vehicle due to the compactness of the electric power equipment 50, etc., and the axial length of the stiffener 47 can be shortened to reduce the moment applied to the stiffener 47 from the second case 42. This makes it possible to satisfactorily suppress the upper portion 42u of the second case 42 from vibrating toward or away from the engine 10 while satisfactorily ensuring the durability of the stiffener 47 and the mounting portions at both ends. Furthermore, when the engine 10 of the vehicle 1 is operated, vibrations generated from the engine 10 are transmitted to the second case 42 via the first case 41 and the stiffener 47. Therefore, high-frequency vibrations from the engine 10 are attenuated by the first case 41 and the stiffener 47 before being transmitted to the second case 42, so that the effect of vibrations on the electric power equipment 50 disposed within the upper portion 42u of the second case 42 can be further reduced.

[0022] As a result, transaxle 20 can reduce the number of parts and size, while reducing vibration and noise and providing good protection for electric power equipment 50. Transaxle 20 may be modified so as to be mounted on a rear-wheel drive vehicle or a four-wheel drive vehicle.

[0023] In addition, the invention of the present disclosure is not limited to the above embodiment, and various modifications can be made within the scope of the present disclosure. Furthermore, the above embodiment is merely a specific form of the invention described in the Summary of the Invention, and does not limit the elements of the invention described in the Summary of the Invention. [Industrial Applicability]

[0024] The invention of the present disclosure can be used in the transaxle manufacturing industry and the like. [Explanation of symbols]

[0025] 1 vehicle, 10 engine, 111 camshaft, 112 cam housing, 20 transaxle, 30 planetary gear, 35 counter drive gear, 36 counter driven gear, 37 drive pinion gear, 38 drive gear, 39 differential gear, 39r differential ring gear, 40 case, 41, first case, 42 second case, 42u upper part, 42l lower part, 42w bulkhead, 45 cover, 47 stiffener, 50 power equipment, MG1, MG2 motor generator.

Claims

[Claim 1] A transaxle having an electric motor, a gear mechanism connected to the electric motor and an engine, and a case accommodating the electric motor and the gear mechanism, the transaxle being mounted on a vehicle, The case is a first case that is shorter than the engine, is fixed to the engine, and houses the gear mechanism; a second case that is shorter than the engine and taller than the first case and that houses the electric motor and an electric device for driving the electric motor; a stiffener having one end fixed to the first case and the other end fixed to a portion of the second case protruding in a height direction from the first case; A transaxle comprising:

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