Drive unit

Abstract

The present invention provides a drive unit that facilitates thermal management of the drive unit by promoting cooling by lubricating oil in the drive unit. [Solution] The transaxle 10 comprises a gear chamber 25 housing gears, a motor chamber housing a rotating mechanism, and a PCU chamber housing a PCU, all housed in a case 20. The gears and rotating mechanism constitute a transmission. The transaxle 10 has an integrated electromechanical structure in which the transmission and PCU are housed in the case 20. The differential ring gear 75, which is immersed in lubricating oil, rotates in a direction in which the portion behind the rotation axis moves downward. A rib 42 is provided on the front wall 41. Part of the side wall 61 also serves as the first bulkhead 31 on the front side of the protruding portion 35. The side wall 61 is positioned so that a portion of the lubricating oil, which is scraped up by the rotation of the differential ring gear 75 and ejected from the tip of the rib 42, collides with the side wall 61 as it scatters toward the second tank 52.

Description

Technical Field

[0001] This invention relates to a drive unit.

Background Art

[0002] Patent Document 1 discloses a drive unit including a transaxle having a one-axis structure in which a motor, a speed reducer, and a differential mechanism are arranged on the same axis. The drive unit of Patent Document 1 has an integrated structure in which a power control unit for controlling the motor and a noise filter are integrated with the transaxle case.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By adopting an integrated structure in which a plurality of devices are arranged in the transaxle case, the drive unit can be miniaturized. However, due to miniaturization, each device is densely arranged, making it difficult to manage the heat of the components in the drive unit.

Means for Solving the Problems

[0005] The drive unit for solving the above problems includes a gear chamber in which a plurality of gears constituting a transmission are accommodated such that their respective rotation axes are along a reference plane that is a horizontal plane in the posture when mounted on a vehicle and are parallel to each other. This drive unit includes a motor chamber in which a rotating machine constituting the transmission is accommodated. This drive unit includes a PCU chamber in which a power control unit for controlling the rotating machine is accommodated.

[0006] This drive unit is an electromechanical drive unit in which the transmission and the power control unit are housed in a case that includes the gear chamber, the motor chamber, and the PCU chamber.

[0007] In this drive unit, the lower part where the gear chamber and the motor chamber are located is separated from the upper part where the PCU chamber is located by a first partition wall. In this drive unit, the gear chamber and the motor chamber are separated by a second partition wall perpendicular to the rotation axis direction of the plurality of gears.

[0008] This drive unit is provided with a gear chamber that includes a first wall portion connected to both the second and first bulkheads and extending downward from the first bulkhead, a projection portion of the PCU chamber that protrudes downward, and a tank for storing lubricating oil below the projection portion. When the direction perpendicular to the rotation axis direction is defined as the front-rear direction on the reference plane of this drive unit, the projection portion and the tank are located behind the first wall portion.

[0009] One of the plurality of gears in this drive unit is a first gear supported at a position below the tank and in front of the first wall, and immersed in lubricating oil. The first gear in this drive unit rotates in a direction in which the portion behind the rotation axis moves downward. The drive unit is provided with a rib on the second wall, which is the wall of the gear chamber adjacent to the front side of the first gear, extending upward and towards the rear along the outer circumference of the first gear from the second wall.

[0010] The first wall portion of this drive unit also serves as the first partition wall on the front side of the protruding portion. The first wall portion of this drive unit is positioned so that a portion of the lubricating oil that is scraped up by the rotation of the first gear and ejected from the tip of the rib, and which is scattered toward the tank, will collide with it. [Effects of the Invention]

[0011] According to the above drive unit, cooling by lubricating oil in the drive unit is promoted, making thermal management of the drive unit easier. [Brief explanation of the drawing]

[0012] [Figure 1] Figure 1 is a schematic side view showing the inside of a transaxle, which is one embodiment of a drive unit. [Figure 2] Figure 2 is a schematic cross-sectional view along the 2-2 section shown in Figure 1. [Figure 3] Figure 3 is a schematic cross-sectional view along the 3-3 section shown in Figure 1. [Figure 4] Figure 4 is a schematic cross-sectional view along the 4-4 cross-sectional line shown in Figure 1, and shows the differential ring gear. [Figure 5] Figure 5 is a schematic cross-sectional view along the same cross-sectional line as Figure 4, showing the second reduction gear. [Figure 6] Figure 6 is a schematic cross-sectional view of the modified transaxle, following the same cross-sectional line as in Figure 4. [Modes for carrying out the invention]

[0013] The transaxle 10, which is one embodiment of the drive unit, will be described below with reference to Figures 1 to 5. The transaxle 10 is mounted on a vehicle. The transaxle 10 is an electromechanical drive unit in which the transmission and the power control unit are integrated. Hereafter, the power control unit will be referred to as PCU.

[0014] <Transaxle 10 Configuration> Figure 1 is a side view of the inside of the transaxle 10, seen from the left side. The transaxle 10 has a reference plane. The reference plane coincides with the horizontal plane of the transaxle 10 when it is mounted on a vehicle.

[0015] FIG. 2 is a cross-sectional view of a cross-section along the 2-2 cross-sectional line shown by the dashed-dotted line in FIG. 1, as viewed from the rear side of the transaxle 10. FIG. 3 is a cross-sectional view of a cross-section along the 3-3 cross-sectional line shown by the dashed-dotted line in FIG. 1, as viewed from the front side of the transaxle 10. FIGS. 1 to 3 show the positional relationship of each component in the gear chamber 25.

[0016] As shown in FIGS. 1 to 3, the transaxle 10 includes a case 20. In the case 20, a gear chamber 25, a motor chamber 26, and a PCU chamber 27 are provided. As shown in FIG. 1, in the gear chamber 25, four gears or gear units, namely, a planetary gear unit 71, a reduction gear 73, a motor gear 74, and a differential ring gear 75, are accommodated. The differential ring gear 75 is a ring gear that constitutes a differential device. The above gears or gear units constitute a transmission. The rotation axes of the above gears and gear units are parallel to each other. The rotation axes of the above gears or gear units extend along a reference plane.

[0017] As shown in FIGS. 1 and 2, in the transaxle 10, the left-right direction is the same as the direction along the above rotation axis on the reference plane. That is, the rotation axis direction of the above gears or gear units extends in the left-right direction. The front-rear direction in the transaxle 10 is a direction orthogonal to the left-right direction on the reference plane.

[0018] As shown in FIG. 1, in the transaxle 10, the differential ring gear 75 is provided at the front, and the planetary gear unit 71 is provided at the rear. In the transaxle 10, when facing forward, the direction on the right hand side is the right direction. In the transaxle 10, when facing forward, the direction on the left hand side is the left direction.

[0019] As shown in FIG. 2, the case 20 is composed of a first case 21, a second case 22, and a third case 23. The case 20 is fitted from the left side of the transaxle 10 in the order of the first case 21, the second case 22, and the third case 23.

[0020] The portion surrounded by the first case 21 and the second case 22 is the gear chamber 25. The portion surrounded by the second case 22 and the third case 23 is the motor chamber 26. An upper portion of the second case 22 is provided with a PCU chamber 27. The PCU chamber 27 is located above the gear chamber 25 and the motor chamber 26.

[0021] As shown in FIGS. 1 and 2, the second case 22 is provided with a second partition wall 32. The second partition wall 32 separates the gear chamber 25 and the motor chamber 26. The second partition wall 32 extends along the front-rear direction and the up-down direction in the transaxle 10. That is, the second partition wall 32 is orthogonal to the left-right direction.

[0022] The second case 22 is provided with a first partition wall 31. The first partition wall 31 separates the PCU chamber 27 from the gear chamber 25 and the motor chamber 26. That is, the first partition wall 31 separates the lower portion of the transaxle 10 where the gear chamber 25 and the motor chamber 26 are provided from the upper portion of the transaxle 10 where the PCU chamber 27 is provided.

[0023] The motor chamber 26 houses a first motor generator and a second motor generator (not shown). The motor generators together with the planetary gear unit 71 housed in the gear chamber 25 constitute a transmission. The motor generators are rotating machines that function as generators and motors.

[0024] The PCU chamber 27 houses a PCU (not shown). The PCU controls the two motor generators. The PCU is a power control unit having an inverter and a converter that convert electric power between a battery mounted on the vehicle and the motor generators. The PCU chamber 27 houses a plurality of components other than the PCU. The transaxle 10 integrally houses the transmission and the PCU in the case 20.

[0025] A portion of the PCU chamber 27 protrudes into the gear chamber 25 and the motor chamber 26. Specifically, the rear portion of the PCU chamber 27 protrudes downward. The portion of the PCU chamber 27 that protrudes into the gear chamber 25 and the motor chamber 26 is referred to as the protruding portion 35. In accordance with the downward protrusion of the protruding portion 35, the first bulkhead 31 in the protruding portion 35 is positioned lower than the first bulkhead 31 in front of the protruding portion 35. In the gear chamber 25, the first bulkhead 31 in front of the protruding portion 35 is referred to as the upper wall 62.

[0026] As shown in Figures 1 and 2, a second tank 52 is provided below the protrusion 35 in the second case 22. The second tank 52 extends to the left from the second bulkhead 32. A first tank 51 is provided in the first case 21. The first tank 51 extends to the right from the left wall of the first case 21. The height of the first tank 51 is the same as the height of the second tank 52.

[0027] The first tank 51 and the second tank 52 form tanks for storing lubricating oil when the first case 21 and the second case 22 are fitted together. Outlet holes 53 are provided in the bottom surfaces of the first tank 51 and the second tank 52. In Figure 1, the outlet hole 53 in the second tank 52 is shown by a dashed line. The outlet hole 53 is a hole that penetrates the bottom surface of the tank. The lubricating oil stored in the tank flows out of the tank through the outlet hole 53.

[0028] <Transmission Configuration> Figure 1 shows axes S1 to S4. The four gears or gear units and the two motor generators are each positioned on one of the four axes S1 to S4 shown in Figure 1. Each gear constituting the transmission is a helical gear. A helical gear is a gear in which the tooth trace is inclined with respect to the gear's axis of rotation.

[0029] Axis S1 is located below the first tank 51 and the second tank 52. Axis S1 is the axis of rotation of the engine output shaft 70, the first rotor shaft 77 which is the rotor shaft of the first motor generator, and the planetary gear unit 71.

[0030] The planetary gear unit 71 comprises a sun gear, a planetary carrier, a ring, and three pinion gears. In the planetary gear unit 71, axis S1 is the axis of rotation of the sun gear, planetary carrier, and ring. The sun gear is located at the center of the planetary gear unit 71. The sun gear is fixed to the first rotor shaft 77, shown by a dashed line in Figure 1. The sun gear is connected to the first motor generator via the first rotor shaft 77. The planetary carrier is connected to the output shaft 70. The planetary carrier is connected to the engine via the output shaft 70. The three pinion gears are arranged around the sun gear, supported by the planetary carrier. The ring has a ring gear on its inner surface and an output gear on its outer surface.

[0031] Axis S2 is located diagonally above and in front of axis S1. Axis S2 is the rotation axis of the reduction gear 73, which is meshed with the output gear of the planetary gear unit 71. The reduction gear 73 consists of a reduction shaft 72, a first reduction gear 73A, and a second reduction gear 73B. The first reduction gear 73A and the second reduction gear 73B are fixed to the reduction shaft 72. In Figure 1, the first reduction gear 73A, which is in front of the second reduction gear 73B, is shown by a dashed line. The output gear of the planetary gear unit 71 is meshed with the first reduction gear 73A.

[0032] Axis S3 is located diagonally above and in front of axis S2. Axis S3 is the axis of rotation of the second rotor shaft 78, which is the rotor shaft of the second motor generator, and the motor gear 74, which is meshed with the first reduction gear 73A. The motor gear 74 is connected to the second motor generator via the second rotor shaft 78.

[0033] Axis S4 is located diagonally below and in front of axis S2. Axis S4 is the axis of rotation for the differential ring gear 75 and the drive shaft 76. The rotating shaft and gear or gear unit described above are also shown in Figures 2 and 3. However, the motor gear 74 and the second rotor shaft 78 are not shown in Figure 3.

[0034] As described above, the output gear on axis S1 receives the driving force from the engine and the first motor generator. The motor gear 74 on axis S3 receives the driving force from the second motor generator. The first reduction gear 73A combines the driving force from the output gear and the driving force from the motor gear 74 and outputs it to the differential ring gear 75 via the second reduction gear 73B. This outputted driving force is transmitted to the left and right drive shafts 76 via the differential ring gear 75 and the differential. The transaxle 10 drives the vehicle with the driving force transmitted to the drive shafts 76.

[0035] The differential ring gear 75 is immersed in lubricating oil stored at the bottom of the transaxle 10. Figure 1 shows the oil level 54 of the lubricating oil stored in the transaxle 10. In Figure 1, the differential ring gear 75 is rotating clockwise. In other words, the differential ring gear 75 is rotating in a direction in which the portion behind the axis of rotation moves downward. The differential ring gear 75 is the first gear.

[0036] The second reduction gear 73B is meshed with the differential ring gear 75 at a position above and behind the axis of rotation of the differential ring gear 75. In Figure 1, the second reduction gear 73B rotates counterclockwise. The second reduction gear 73B is the second gear.

[0037] <Lubrication of the transmission and cooling of the PCU chamber 27> As shown in Figure 1, the differential ring gear 75 is supported at the front of the gear chamber 25. The front wall of the gear chamber 25 is adjacent to the front side of the differential ring gear 75. This wall is referred to as the front wall 41. The front wall 41 is the second wall section.

[0038] As shown in Figure 1, the front wall 41 is provided with a rib 42. The rib 42 extends in an arc shape along the outer circumference of the differential ring gear 75. The rib 42 extends upward from the front wall 41. The rib 42 is located further back the higher it is above it.

[0039] Figure 3 virtually shows the position of the rib 42, which is in front of the 3-3 section line, with a dashed line. As shown in Figure 3, the rib 42 is positioned in the same location as the differential ring gear 75 in the left-right direction.

[0040] As shown in Figures 2 and 3, the differential ring gear 75 and the second tank 52 are positioned at the same location in the left-right direction. The differential ring gear 75 is supported below the second tank 52.

[0041] As shown in Figure 3, the gear chamber 25 is provided with a side wall 61. As shown in Figure 1, approximately the upper half of the side wall 61 also serves as the first bulkhead 31 on the front side of the protruding portion 35. In other words, the side wall 61 is connected to both the second bulkhead 32 and the first bulkhead 31. The side wall 61 extends further downward from the first bulkhead 31 on the front side of the protruding portion 35. That is, the side wall 61 protrudes downward at the front end of the protruding portion 35.

[0042] As shown in Figure 3, the portion protruding downwards has a roughly fan-like shape when viewed from the front. The side wall 61 is the first wall section. As shown in Figure 1, the differential ring gear 75 is located in front of the side wall 61. The second tank 52 is located behind the side wall 61. As shown in Figures 1 and 3, the second reduction gear 73B is located below the side wall 61.

[0043] As shown in Figure 3, the left end of the side wall 61 is located to the right of the left end of the second tank 52. In other words, when viewed from the front, the side wall 61 does not completely overlap with the second tank 52. When viewed from the front, the side wall 61 is positioned to cover the right side of the second tank 52.

[0044] In the transaxle 10, when the differential ring gear 75 rotates, the lubricating oil churned up by the rotation of the differential ring gear 75 is ejected from the tip of the rib 42, as shown by arrows 91 and 92 in Figures 1 and 3. The ejected lubricating oil is scattered toward the second tank 52, as shown by arrows 91 and 92.

[0045] The dashed arrow 91 in Figures 1 and 3 indicates the trajectory of lubricating oil ejected from a position slightly to the left of the differential ring gear 75. As indicated by arrow 91, the ejected lubricating oil scatters toward the second tank 52 and is stored in the tank. The lubricating oil stored in the tank flows out through the outlet hole 53 and falls, lubricating the planetary gear unit 71 located below the tank.

[0046] The arrow 92 shown as a solid line in Figures 1 and 3 indicates the trajectory of lubricating oil launched from a position slightly to the right of the differential ring gear 75. As indicated by arrow 92, the launched lubricating oil collides with the side wall 61 on its way to the second tank 52. In other words, the side wall 61 is positioned so that a portion of the lubricating oil launched towards the second tank 52 will collide with it.

[0047] As shown in Figure 4, the differential ring gear 75 is a helical gear. Figure 4 shows only the differential ring gear 75 among the multiple gears in the gear chamber 25. When the differential ring gear 75 is rotating, the teeth located above the axis of rotation move in the direction indicated by arrow 94 in Figure 4. Each tooth of the differential ring gear 75 has its front side in the direction of rotation facing the second bulkhead 32.

[0048] As shown in Figure 5, the second reduction gear 73B is a helical gear. Figure 5 shows only the second reduction gear 73B among the multiple gears in the gear chamber 25. When the second reduction gear 73B is rotating, the teeth located above the axis of rotation move in the direction indicated by arrow 95 in Figure 5. Each tooth of the second reduction gear 73B has its front side in the direction of rotation facing the second partition wall 32.

[0049] As shown by the dashed line in Figure 5, when viewed from above the gear chamber 25, the left end of the upper wall 62 is located to the right of the left end of the second reduction gear 73B. <Operation of this embodiment> The lubricating oil raked up by the differential ring gear 75 moves upward along the rib 42 and is ejected from the tip of the rib 42. The ejected lubricating oil is scattered toward the second tank 52 located behind the side wall 61, as shown by arrows 91 and 92 in Figures 1 and 3. Some of this scattered lubricating oil collides with the side wall 61, which also serves as part of the wall of the PCU chamber 27, as shown by arrow 92. The lubricating oil that collides with the side wall 61 cools the side wall 61. Cooling the wall of the PCU chamber 27 promotes the cooling of the components housed inside the PCU chamber 27, including the PCU. The transaxle 10 can use some of the lubricating oil collected in the tanks, which consist of the first tank 51 and the second tank 52, to cool the PCU chamber 27.

[0050] <Effects of this embodiment> (1) The transaxle 10 facilitates cooling by lubricating oil in the transaxle 10, making thermal management of the transaxle 10 easier.

[0051] (2) One of the multiple gears of the transaxle 10 is a second reduction gear 73B that meshes with the differential ring gear 75 at a position above and behind the axis of rotation of the differential ring gear 75. The second reduction gear 73B of the transaxle 10 is located below the side wall 61.

[0052] In the transaxle 10, the lubricating oil scooped up by the differential ring gear 75 collides with the side wall 61 and then falls downward as shown by arrow 93A in Figure 1. The fallen lubricating oil adheres to the second reduction gear 73B located below the side wall 61. The lubricating oil adhering to the second reduction gear 73B is scattered into the gear chamber 25 by the rotation of the second reduction gear 73B. The second reduction gear 73B, which is meshed with the differential ring gear 75, rotates in a direction in which the portion of the second reduction gear 73B behind its axis of rotation moves upward. The lubricating oil that falls from the side wall 61 and is scattered by the rotating second reduction gear 73B is scattered upwards towards the top of the gear chamber 25, above the second reduction gear 73B, as shown by arrow 93B in Figure 1. Lubricating oil scattered from the second reduction gear 73B collides with and adheres to the upper wall 62, which is part of the first bulkhead 31 separating the PCU chamber 27 and the gear chamber 25. The lubricating oil adhering to the upper wall 62 then cools the upper wall 62, which is part of the wall of the PCU chamber 27. The transaxle 10 further promotes the cooling of the PCU by scattering the lubricating oil that has fallen from the side wall 61 again with the second reduction gear 73B, causing it to adhere to the upper wall 62.

[0053] With the transaxle 10, the lubricating oil used to lubricate the gears can be used more efficiently to cool the transaxle 10. (3) The differential ring gear 75 of the transaxle 10 is a helical gear whose tooth trace is inclined with respect to the axis of rotation. Each tooth of the differential ring gear 75 has its front side in the direction of rotation facing the second bulkhead 32.

[0054] When a helical gear rotates with lubricating oil attached, the lubricating oil tends to scatter in the direction in which the tooth traces are inclined relative to the rotation direction of the helical gear. The side wall 61 is connected to the second bulkhead 32. When the differential ring gear 75 rotates in the direction indicated by arrow 94 in Figure 4, the lubricating oil scattered upward from the differential ring gear 75 tends to scatter toward the side wall 61, as indicated by arrow 101 in Figure 4.

[0055] The transaxle 10 allows for an increase in the amount of lubricating oil that collides with the side wall 61, thereby enhancing the cooling effect. (4) The second reduction gear 73B of the transaxle 10 is a helical gear. Each tooth of the second reduction gear 73B has its front side in the direction of rotation facing the second bulkhead 32. When the second reduction gear 73B rotates in the direction indicated by arrow 95 in Figure 5, the lubricating oil that is scattered upward from the second reduction gear 73B tends to scatter toward the upper wall 62, as indicated by arrow 102 in Figure 5.

[0056] The transaxle 10 can increase the amount of lubricating oil that strikes the upper wall 62, thereby enhancing the cooling effect. <Example of changes> This embodiment can be implemented with the following modifications. This embodiment and the following modifications can be combined with each other to the extent that they do not contradict each other technically.

[0057] The first gear does not have to be the differential ring gear 75. Any gear that is adjacent to the front wall 41 of the gear chamber 25, immersed in lubricating oil, and rotates in a direction in which the portion behind the rotating shaft moves downward does not have to be the ring gear that constitutes the differential.

[0058] The first gear and the second gear do not need to be directly meshed. The second gear only needs to be a gear located below the side wall 61. The second gear only needs to be a gear that rotates in a direction that catches the lubricating oil that has fallen upon impact with the side wall 61 and scatters the lubricating oil toward the upper wall 62.

[0059] The differential ring gear 75 and the second reduction gear 73B do not have to be helical gears. For example, as shown in Figure 6, the differential ring gear 75 does not have to be a helical gear. If the differential ring gear 75 is a spur gear, when the differential ring gear 75 rotates in the direction indicated by arrow 94 in Figure 6, lubricating oil is sprayed straight backward from the rib 42, as indicated by arrow 103 in Figure 6. In the modified transaxle 10, the lubricating oil sprayed from the rib 42 by the rotation of the differential ring gear 75 is more easily stored in the second tank 52. According to the modified transaxle 10, a large amount of lubricating oil scraped up from the differential ring gear 75 can be used to lubricate the planetary gear unit 71. [Explanation of Symbols]

[0060] 10…Transaxle, 20…Case, 25…Gear chamber, 26…Motor chamber, 27…PCU chamber, 31…First bulkhead, 32…Second bulkhead, 35…Protrusion, 41…Front wall, 42…Rib, 51…First tank, 52…Second tank, 61…Side wall, 62…Top wall, 73…Reduction gear, 73A…First reduction gear, 73B…Second reduction gear, 75…Differential ring gear

Claims

1. A case comprising: a gear chamber in which multiple gears constituting the transmission are housed such that their respective rotation axes are aligned with a reference plane which is the horizontal plane in the vehicle's orientation and are parallel to each other; a motor chamber in which the rotating mechanism constituting the transmission is housed; and a PCU chamber in which a power control unit for controlling the rotating mechanism is housed; A mechatronic drive unit housing the aforementioned transmission and the aforementioned power control unit, The lower part where the gear chamber and the motor chamber are located and the upper part where the PCU chamber is located are separated by a first partition wall. The gear chamber and the motor chamber are separated by a second partition wall perpendicular to the rotation axis direction of the plurality of gears. The gear chamber is provided with a first wall portion connected to both the second and first partition walls and extending downward from the first partition wall, a protruding portion of the PCU chamber that extends downward, and a tank for storing lubricating oil below the protruding portion. When the direction perpendicular to the rotation axis direction in the reference plane is defined as the front-rear direction, the protrusion and the tank are located behind the first wall. One of the plurality of gears is a first gear supported at a position below the tank and in front of the first wall and immersed in lubricating oil, the first gear rotates in a direction in which the portion behind the rotation axis moves downward, and the second wall, which is the wall of the gear chamber adjacent to the front side of the first gear, is provided with ribs that extend upward and backward along the outer circumference of the first gear from the second wall. The first wall portion also serves as the first partition wall on the front side of the protruding portion, and is positioned so that a portion of the lubricating oil that is scraped up by the rotation of the first gear and ejected from the tip of the rib, and which is scattered toward the tank, will collide with it. Drive unit.

2. One of the aforementioned multiple gears is a second gear that meshes with the first gear at a position above and behind the axis of rotation of the first gear. The second gear is located below the first wall. The drive unit according to claim 1.

3. The first gear is a ring gear that constitutes a differential, and the second gear is a reduction gear that meshes with the ring gear. The drive unit according to claim 2.

4. The first gear is a helical gear in which the tooth trace is inclined with respect to the axis of rotation, and the front side of each tooth in the direction of rotation of the first gear faces the second partition wall. The drive unit according to any one of claims 1 to 3.

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