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 mounted on a vehicle.

Background Art

[0002] Conventionally, a hybrid vehicle including an engine, a transaxle including two motors, and a power converter that converts the power of a power source into the driving power of 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. Further, the power converter is supported with a gap provided above the transaxle 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

Summary of the Invention

Problems to be Solved by the Invention

[0004] Here, if the power converter as described above is housed in the case of the transaxle, the number of parts can be reduced by omitting brackets and the like, and the entire transaxle including the power converter can be downsized. However, in a transaxle in which the power converter is housed in the case, the weight of the power converter is added, so that the weight of the entire transaxle increases, and the resonance frequency of the housing portion of the power converter of the transaxle and the case decreases. For this reason, resonance of the entire transaxle may occur due to the driving force (vibration) from the engine, resulting in increased vibration and noise, or the vibration (high-frequency vibration) from the engine may adversely affect the components of the power converter in the case.

[0005] Therefore, the primary objective of this disclosure is to provide a transaxle that can reduce vibration and noise while miniaturizing the number of parts and providing good protection for power equipment. [Means for solving the problem]

[0006] The transaxle of the present disclosure is a transaxle mounted on a vehicle, comprising 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 comprises a first case that is lower in height than the engine, fixed to the engine and housing the gear mechanism; a second case that is lower in height than the engine and taller than the first case, housing the electric motor and power equipment for driving the electric motor; and a stiffener, one end of which is fixed to the first case and the other end of which is fixed to a portion of the second case that protrudes in height from the first case.

[0007] In the transaxle of this disclosure, brackets, bushings, bolts for fixing power equipment to the case, and cases for housing power equipment can be omitted, thereby reducing the number of parts and making the entire device smaller. Furthermore, a stiffener is provided between the first case and the 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. In addition, since the second case is lower in profile than the engine, the axial length of the stiffener can be shortened, reducing the moment applied to the stiffener from the second case. This effectively suppresses vibrations that cause the second case to move closer to or further away from the engine, and ensures good durability of the stiffener. Moreover, since high-frequency vibrations from the engine are attenuated by the first case and stiffener before propagating to the second case, the impact of vibrations on power equipment placed inside the second case can be further reduced. As a result, the transaxle of this disclosure can reduce vibrations and noise and protect power equipment well while reducing the number of parts and making the device smaller. [Brief explanation of the drawing]

[0008] [Figure 1] This is a schematic diagram of a vehicle including the transaxle of the present disclosure. [Figure 2] This is a schematic diagram illustrating the transaxle of the present disclosure. [Modes for carrying out the invention]

[0009] Next, with reference to the drawings, embodiments for carrying out the invention of this disclosure will be described.

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

[0011] As shown in Figure 1, the transaxle 20 includes, in addition to motor generators MG1 and MG2, a planetary gear 30, a differential gear 39, and a case 40 housing these elements. The motor generator MG1 (first motor) is a synchronous regenerative motor (three-phase AC motor) including a stator S1 and a rotor R1, and operates as a generator that converts at least a portion of the power from the engine 10, which is mainly under load operation, into electricity. The motor generator MG2 (second motor) is a synchronous regenerative motor (three-phase AC motor) including a stator S2 and a rotor R2, and operates as a motor that generates driving torque, mainly driven by power from the battery and at least one of the motor generator MG1.

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

[0013] The counter drive gear 35 is connected to the left and right wheels (drive wheels) W via the counter driven gear 36 that meshes with the counter drive gear 35, the drive pinion gear (final drive gear) 37 that rotates integrally with the counter driven gear 36, the differential ring gear 39r that meshes with the drive pinion gear 37 and rotates integrally with the differential case of the differential gear 39, the differential gear 39, and the drive shaft DS. The gear mechanism of the transaxle 20, that is, the gear train from the planetary gear 30 and 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 source to the drive shaft DS and the wheels W.

[0014] Furthermore, the motor generator MG2's rotor R2 is connected (fixed) to the drive gear 38 via the motor shaft MS so that it rotates integrally with it. The drive gear 38 has fewer 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, counter-driven gear 36, drive pinion gear 37, differential ring gear 39r, and differential gear 39. In other words, the motor generator MG2 functions as a power source that outputs driving torque (driving 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 the vehicle 1 is braked.

[0015] The transaxle 20 case 40 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 castings made of, for example, aluminum alloy or steel. As shown in Figures 1 and 2, the first case 41 is fastened (connected) to the engine block (cylinder block) 110 of the engine 10 via a plurality of bolts so as to be adjacent in the width direction of the vehicle 1. The second case 42 is fastened (connected) to the first case 41 via a plurality of bolts so as to be adjacent in the width direction of the vehicle 1, and together with the first case 41 constitutes the case body. The cover 45 is fastened (connected) to the second case 42 via a plurality of bolts so as to cover the open end of the second case 42 opposite to the first case 41 side.

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

[0017] The power equipment 50 includes a first inverter, a second inverter, a boost converter, a filter capacitor, a smoothing capacitor, a DC / DC converter, an electronic control unit, etc. The first inverter drives the motor generator MG1, and the second inverter drives the motor generator MG2. The boost converter boosts the power from the battery and steps down the power from the motor generators MG1 and MG2. The DC / DC converter is connected to the power line connecting the battery and the boost converter, as well as to an auxiliary battery and several auxiliary devices, and steps down the power from the battery and boost converter to a target voltage before supplying it to the auxiliary battery and auxiliary devices. The electronic control unit includes a microcomputer and various drive circuits, etc., and controls the first and second inverters and the boost converter.

[0018] As shown in Figure 2, the first case 41 is formed to be lower in height than the engine 10. The second case 42 is formed to be lower in height than the engine 10 and higher in height 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 above (in the height direction) the upper surface of the first case 41, and the core plate 42p fixed to the upper end of the second case 42 is located below at least the camshaft 111 of the engine 10, and more specifically below the cam housing 112 that supports the camshaft 111 and is fixed to the engine block 110. The power equipment 50 described above is housed in the upper part 42u of the second case 42 that protrudes above the first case 41. In this embodiment, at least a portion of the power equipment 50 is attached to the core plate 42p, and the motor generators MG1 and MG2 are housed in the lower part 42l of the second case 42 so as to be located below the power equipment 50.

[0019] Furthermore, as shown in Figure 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) 47 is placed in this 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 the side surface of the upper part 42u of the second case 42 which protrudes above the first case 41. As a result, when the transaxle 20 is mounted on the vehicle body of the vehicle 1, the stiffener 47 extends diagonally so that it is positioned upward from the first case 41 toward the second case 42. Furthermore, any structure can be used for fixing the stiffener 47 to the first and second cases 41 and 42.

[0020] In the transaxle 20 configured as described above, brackets, bushings, bolts for fixing the power equipment 50 to the case 40, and a case for housing the power equipment 50 can be omitted, thereby reducing the number of parts and making the entire device smaller. On the other hand, the weight of the power equipment 50 is added, increasing the overall weight of the transaxle 20, and the resonant frequency of the transaxle and the upper part 42u of the second case 42 that houses (supports) the 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 above the first case 41, may vibrate in a way that moves it closer to or further away from the engine 10 due to resonance caused by the coercive force (vibration) from the engine 10 (see the dashed arrow in Figure 2). However, as described above, a stiffener 47 is provided between the top surface of the first case 41 and the upper part 42u of the second case 42. As a result, the upper part (protruding portion) 42u of the second case 42 is supported by the first case 41 via the stiffener 47, which effectively suppresses vibrations that cause the upper part 42u to move closer to or further away from the engine 10.

[0021] Furthermore, in the transaxle 20, the second case 42 is made lower in height so that the core plate 42p is positioned below the camshaft 111 and cam housing 11 of the engine 10 when mounted on the vehicle, due to the miniaturization of power equipment 50, etc., the axial length of the stiffener 47 can be shortened, and the moment applied to the stiffener 47 from the second case 42 can be reduced. This makes it possible to effectively suppress vibrations that cause the upper part 42u of the second case 42 to move closer to or further away from the engine 10, while ensuring good durability of the stiffener 47 and the mounting parts at both ends. Moreover, when the engine 10 of the vehicle 1 is operated, vibrations emitted from the engine 10 are transmitted to the second case 42 via the first case 41 and stiffener 47. Therefore, high-frequency vibrations from the engine 10 are attenuated by the first case 41 and stiffener 47 before being transmitted to the second case 42, thus further reducing the impact of vibrations on the power equipment 50 located in the upper part 42u of the second case 42.

[0022] As a result, in the transaxle 20, while reducing the number of parts and miniaturizing, it is possible to reduce vibration and noise and to protect the electric power device 50 well. Note that the transaxle 20 may be modified to be mounted on a rear-wheel drive vehicle or a four-wheel drive vehicle.

[0023] Also, the invention of the present disclosure is not limited to the above-described embodiments at all, and it is needless to say that various changes can be made within the scope of the disclosure. Further, the above-described embodiments are merely specific forms of the invention described in the summary section of the invention, and do not limit the elements of the invention described in the summary section of the invention.

Industrial Applicability

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

Explanation of Signs

[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 Def Ring Gear, 40 Case, 41 First Case, 42 Second Case, 42u Upper, 42l Lower, 42w Partition Wall, 45 Cover, 47 Stiffener, 50 Electric Power Device, MG1, MG2 Motor Generator.

Claims

[Claim 1] A transaxle mounted on a vehicle, comprising an electric motor, a gear mechanism connected to the electric motor and the engine, and a case housing the electric motor and the gear mechanism, The aforementioned case is, A first case that is lower in height than the engine, is fixed to the side of the engine, and houses the gear mechanism, A second case is fixed to the side of the first case opposite to the engine, is lower in height than the engine and higher in height than the first case, and has an upper part that protrudes above the first case and a lower part that is located below the upper part, housing the electric motor in the lower part and power equipment for driving the electric motor in the upper part. A stiffener, one end of which is fixed to the first case and the other end of which is fixed to the upper part of the second case, A transaxle equipped with a transaxle.

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