Power transmission mechanism

Abstract

To provide a power transmission mechanism capable of improving lubrication inside a differential case.SOLUTION: A power transmission mechanism 16 includes a main shaft 28 provided with a drive gear 32 for setting a shift stage, a differential gear 80 to which power is transmitted from the main shaft 28, and a case 70 for storing the main shaft 28 and the differential gear 80. In the power transmission mechanism 16, (a) the deferential gear 80 is arranged above the main shaft 28, and (b) the case 70 has a case cylinder part 74t for storing the lubricant OIL scooped up by the drive gear 32 to be introduced to the deferential gear 80. With the case tubular portion 74t, the lubricant OIL stored in the case tubular portion 74t is efficiently introduced into the diff case 82, so that the lubrication of the diff gear 80 is improved.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a power transmission mechanism that includes a shaft provided with a gear that sets a gear position, a differential gear to which power is transmitted from the shaft, and a case that houses the shaft and the differential gear. [Background technology]

[0002] There is known a power transmission mechanism that includes a shaft provided with a gear that sets a gear position, a differential gear to which power is transmitted from the shaft, and a case that houses the shaft and the differential gear. For example, the mechanism described in Patent Document 1 is such a mechanism. In the power transmission mechanism described in Patent Document 1, the lower part of the differential case is submerged in lubricating oil stored in the bottom of the case. The lubricating oil stored in the bottom of the case is scooped up by a scooping plate that rotates together with the differential case, and this scooped up lubricating oil is introduced into the differential case through an opening formed in the differential case to lubricate the differential gear. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-152266 Summary of the Invention [Problem to be solved by the invention]

[0004] In a power transmission mechanism that includes a shaft with a gear that sets the gear position, a differential gear to which power is transmitted from the shaft, and a case that houses the shaft and the differential gear, the lower part of the differential case may not be submerged in the lubricating oil stored in the bottom of the case. In such a configuration, there is a risk that the lubricating oil will not be sufficiently introduced into the differential case due to the oil being scooped up, resulting in insufficient lubrication of the differential gear.

[0005] The present invention has been made in light of the above circumstances, and an object of the present invention is to provide a power transmission mechanism that improves lubrication inside the differential case. [Means for solving the problem]

[0006] The gist of the present invention is a power transmission mechanism comprising a shaft provided with a gear for setting a gear position, a differential gear to which power is transmitted from the shaft, and a case for accommodating the shaft and the differential gear, wherein (a) the differential gear is disposed above the shaft, and (b) the case has a storage section for storing lubricating oil scooped up by the gear for introduction into the differential gear. [Effects of the Invention]

[0007] According to the power transmission mechanism of the present invention, (a) the differential gear is disposed above the shaft, and (b) the case has a reservoir that stores lubricating oil scooped up by the gear for introduction into the differential gear. Even when the differential gear is disposed above the shaft on which the gear that scoops up the lubricating oil is provided, the lubricating oil is stored in the reservoir of the case. As a result, compared to when no reservoir is provided, when the reservoir is provided, the lubricating oil stored in the reservoir is efficiently introduced into the differential case, improving lubrication of the differential gear. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a schematic diagram illustrating a schematic configuration of a vehicle equipped with a power transmission mechanism to which the present invention is applied. [Figure 2] 10 is a diagram illustrating the arrangement of a pair of left and right drive shafts connected to a main shaft, a counter shaft, and a differential gear, as viewed from the second axial direction. FIG. [Figure 3]3 is a diagram illustrating a case tubular portion provided in the case, and is a cross-sectional view taken along the cutting line iii-iii shown in FIG. 2. FIG. [Figure 4] FIG. 2 is a perspective view of a differential case and a differential ring gear of the differential gear. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that in the embodiments, the drawings are appropriately simplified or modified, and the dimensional ratios and shapes of the various parts are not necessarily drawn accurately. [Example]

[0010] FIG. 1 is a schematic diagram illustrating the general configuration of a vehicle 10 equipped with a power transmission mechanism 16 to which the present invention is applied. The vehicle 10 includes the power transmission mechanism 16 in a power transmission path between an engine 12 and a pair of left and right drive wheels 14. The pair of left and right drive wheels 14 are a left wheel 14l and a right wheel 14r. The engine 12 is a power source for traveling and is a well-known internal combustion engine. The vehicle 10 is, for example, a front engine, rear drive (FR) vehicle. The power transmission mechanism 16 includes, in order from the engine 12 side, a clutch K1, a bevel gear pair 24, a transmission 26, and a differential gear 80. Of the power transmission mechanism 16, the bevel gear pair 24, the transmission 26, and the differential gear 80 are housed in a case 70, which is a non-rotating member. One end of the clutch K1 is connected to the engine 12 via a propeller shaft 18, and the other end is connected to one of the bevel gear pair 24. The other of the bevel gear pair 24 is connected to a main shaft 28 of a transmission 26, which will be described later.

[0011] The transmission 26 is a parallel two-shaft transmission that includes a main shaft 28 and a countershaft 52 that are arranged horizontally and parallel to each other. The transmission 26 achieves multiple gear stages (speed stages) by slowing or speeding up the rotation of the main shaft 28 at a predetermined gear ratio γ (also referred to as the speed ratio γ). The gear ratio γ is the ratio of the rotational speed of the main shaft 28 to the rotational speed of the countershaft 52 (= rotational speed of the main shaft 28 / rotational speed of the countershaft 52). The main shaft 28 is rotatable about a first axis C1, and the countershaft 52 is rotatable about a second axis C2. The first axis C1 and the second axis C2 extend horizontally in the same direction. An output gear 52g provided on the countershaft 52 meshes with a differential ring gear (final gear) 84 provided on the differential gear 80, thereby connecting the countershaft 52 and the differential gear 80. The differential gear 80 and the pair of left and right drive wheels 14 are connected via a pair of left and right drive shafts 20. The pair of left and right drive shafts 20 are arranged rotatably about a third axis C3, and the third axis C3 and the second axis C2 are parallel to each other. The pair of left and right drive shafts 20 are a drive shaft 20l for the left wheel and a drive shaft 20r for the right wheel.

[0012] The transmission 26 includes a plurality of gear pairs 30. Each gear pair 30 includes a drive gear 32 fixed to the main shaft 28 so as not to rotate relative thereto, and a driven gear 34 that is constantly meshed with the drive gear 32, is rotatable relative to the counter shaft 52, and is immovable in the second axis C2 direction. The plurality of gear pairs 30 are provided, in order from one side of the first axis C1 direction (= second axis C2 direction), as a reverse gear pair 30a, a second-speed gear pair 30b, a first-speed gear pair 30c, a fourth-speed gear pair 30d, a fifth-speed gear pair 30e, a sixth-speed gear pair 30f, and a third-speed gear pair 30g. The gear ratio γ decreases from first gear pair 30c to second gear pair 30b, third gear pair 30g, fourth gear pair 30d, fifth gear pair 30e, and sixth gear pair 30f. Reverse gear pair 30a has an intermediate gear 36 between the drive gear 32 and the driven gear 34 that meshes with both of them to reverse the direction of rotation. Hereinafter, unless otherwise specified, reverse gear pair 30a to third gear pair 30g will be referred to as "gear pair 30." When the drive gear 32 of a gear pair 30 rotates, the driven gear 34 rotates at a rotational speed corresponding to the gear ratio γ of that gear pair 30.

[0013] In the direction of the second axis C2, the transmission 26 includes switching mechanisms 40 on one side of the driven gear 34 of the reverse gear pair 30a, between the driven gears 34 of the second-speed gear pair 30b and the first-speed gear pair 30c, between the driven gears 34 of the fourth-speed gear pair 30d and the fifth-speed gear pair 30e, and between the driven gears 34 of the sixth-speed gear pair 30f and the third-speed gear pair 30g. The switching mechanisms 40 are non-rotatable relative to the countershaft 52 and movable in the direction of the second axis C2. Each of the switching mechanisms 40 has switching meshing teeth 42 at a position facing the driven gear 34 in the direction of the second axis C2. Each of the driven gears 34 has gear-side meshing teeth 44 that can mesh with the switching meshing teeth 42 at a position facing the switching mechanism 40 in the direction of the second axis C2. The switching mechanism 40 having the switching meshing teeth 42 and the driven gear 34 having the gear-side meshing teeth 44 constitute a dog clutch 50 which is a meshing clutch.

[0014] The shift mechanism 60 includes shift forks 62 that fit into the switching mechanism 40, a shift barrel 64, and a shift actuator 66. The shift barrel 64 is formed with shift grooves 68 that define the movement positions of the switching mechanism 40 in the direction of the second axis C2 via the shift forks 62. The transmission 26 changes gears by moving the switching mechanism 40 to specific positions in the direction of the second axis C2 in accordance with the rotational position of the shift barrel 64, thereby switching the engagement and disengagement states of the dog clutch 50. For example, when the driven gear 34 of the reverse gear Rev and the countershaft 52 are connected via the switching mechanism 40, the reverse gear Rev is established in the transmission 26. The same applies to the first gear 1st to the sixth gear 6th. The drive gear 32 and the driven gear 34 are both gears that set the gears.

[0015] 2 is a diagram illustrating the arrangement of the pair of left and right drive shafts 20 connected to the main shaft 28, the counter shaft 52, and the differential gear 80, as viewed from the direction of the second axis C2. In FIG. 2, only the outer edge of the case 70 (a third case portion 76 described below) to which fasteners such as bolts are fastened is shown.

[0016] For example, lubricating oil OIL for lubricating the gears is stored at the bottom of the case 70. The lubricating oil OIL functions not only for lubrication but also for cooling. The drive gear 32, which is fixed to the main shaft 28, is located in a position where it can scoop up the lubricating oil OIL. The "scraping position" refers to a position where it can scoop up the lubricating oil OIL relative to the working oil level of the lubricating oil stored at the bottom of the case 70. The "working oil level" refers to the height of the lubricating oil OIL stored at the bottom of the case 70 in a normal state. The "normal state" refers to a relatively long-lasting running state, as opposed to a temporary state such as when the vehicle 10 suddenly accelerates or decelerates, travels on a slope, or makes a sharp turn. On the other hand, the countershaft 52 is located above the main shaft 28 in the vertical direction (hereinafter simply referred to as "above"). As a result, the driven gear 34 provided on the countershaft 52 is not located in a position where it can scoop up the lubricating oil OIL. Similarly, the differential gear 80 and the pair of left and right drive shafts 20 connected to the differential gear 80 are disposed above the main shaft 28. As a result, the differential ring gear 84 provided on the differential gear 80 is not in a position where it can scoop up the lubricating oil. The lubricating oil is scooped up by the drive gear 32 and used to lubricate the gears and bearings inside the case 70. Furthermore, as a gear inside the case 70 (for example, the driven gear 34) rotates, the lubricating oil adhering to the gear is further splashed around.

[0017] For example, in a vehicle 10 in which the propeller shaft 18 and the clutch K1 are located at a relatively low position in the vertical direction and the rotational center lines of the pair of left and right drive wheels 14 are located at a relatively high position, the main shaft 28, the countershaft 52, and the differential gear 80 are arranged as described using Figure 2.

[0018] FIG. 3 is a diagram illustrating the case tubular portion 74t provided in the case 70, and is a cross-sectional view taken along the cutting line iii-iii shown in FIG.

[0019] The case 70 is made of, for example, an aluminum alloy casting, and includes, for example, a first case portion 72, a second case portion 74, and a third case portion 76.

[0020] The first case portion 72 is a cylindrical member with a bottom and has an opening on the left wheel 14l side in the direction of the third axis C3. The second case portion 74 is a cylindrical member and has openings on the right wheel 14r side and the left wheel 14l side in the direction of the third axis C3. The third case portion 76 is a cylindrical member with a bottom and has an opening on the right wheel 14r side in the direction of the third axis C3. The first case portion 72 and the second case portion 74 are integrally connected by fasteners such as bolts so that the opening on the left wheel 14l side of the first case portion 72 and the opening on the right wheel 14r side of the second case portion 74 are aligned. The second case portion 74 and the third case portion 76 are integrally connected by fasteners such as bolts so that the opening on the left wheel 14l side of the second case portion 74 and the opening on the right wheel 14r side of the third case portion 76 are aligned.

[0021] The second case portion 74 has a cylindrical case portion 74t on its inner side. The case portion 74t is formed so that its inner peripheral surface faces the outer peripheral surface of the right-wheel drive shaft 20r with a gap S therebetween. The right wheel 14r and the right-wheel drive shaft 20r correspond to the "drive wheels" and "drive shafts" of the present invention, respectively. The case portion 74t has a function of storing lubricating oil scooped up by the drive gear 32 in the gap S so that it can be introduced into the differential gear 80. The case portion 74t corresponds to the "storage portion" of the present invention. For example, when the main shaft 28 rotates while the vehicle is running, the drive gear 32 fixed to the main shaft 28 scoops up the lubricating oil and scatters it around. Furthermore, when the driven gear 34 provided on the countershaft 52 rotates, the lubricating oil adhering to the driven gear 34 is scattered around. For example, the case cylindrical portion 74t is provided with an oil introduction passage 74in to facilitate entry of lubricating oil into the gap S. The oil introduction passage 74in is, for example, a through-hole provided in the lower part of the case cylindrical portion 74t. In this way, the lubricating oil scooped up by the drive gear 32 enters the gap S directly or indirectly via the path indicated by the white arrow and is stored there. The main shaft 28 and the drive gear 32 correspond to the "shaft" and "gear" in this invention, respectively.

[0022] Power is transmitted to the differential gear 80 from the main shaft 28 via the counter shaft 52 in the transmission 26. The differential gear 80 receives power transmitted from the output gear 52g of the transmission 26 and transmits equal drive torque to the pair of left and right drive shafts 20 while allowing for an appropriate difference in rotational speed.

[0023] The differential gear 80 includes a differential case 82 , a differential ring gear 84 , a pair of differential pinions 86 , and a pair of differential side gears 88 .

[0024] The differential case 82 is formed by integrally connecting multiple members with fasteners such as bolts. The differential case 82 is rotatable about the third axis C3 and has a hollow portion therein. The differential case 82 has a large diameter portion 82a and a small diameter portion 82b that protrudes from the large diameter portion 82a toward the right wheel 14r in the direction of the third axis C3. Both the large diameter portion 82a and the small diameter portion 82b are cylindrical. The right wheel 14r side of the small diameter portion 82b in the direction of the third axis C3 is an opening 82r. The left wheel 14l side of the large diameter portion 82a in the direction of the third axis C3 is an opening 82l. The left wheel 14l side of the small diameter portion 82b in the direction of the third axis C3 is connected to the outer edge of the small diameter portion 82b and the outer edge of the large diameter portion 82a.

[0025] The differential ring gear 84 is disk-shaped and centered on the third axis C3, with gear teeth provided on its outer periphery. The inner periphery of the differential ring gear 84 forms a through-hole that penetrates in the direction of the third axis C3. With the large diameter portion 82a of the differential case 82 inserted into the through-hole of the differential ring gear 84, the differential ring gear 84 and the differential case 82 are integrally connected by fasteners such as bolts.

[0026] The pair of differential pinions 86 and the pair of differential side gears 88 are both housed in a hollow portion inside the differential case 82. When the vehicle 10 is traveling straight, the pair of differential pinions 86 do not rotate, and the rotation of the differential case 82 rotates the pair of differential side gears 88 via the pair of differential pinions 86. When the vehicle 10 is turning, the pair of differential pinions 86 rotate, and the rotation of the differential case 82 transmits equal driving torque to the pair of differential side gears 88 via the pair of differential pinions 86 while allowing for an appropriate rotational speed difference.

[0027] FIG. 4 is a perspective view of the differential case 82 and the differential ring gear 84 of the differential gear 80.

[0028] Although not shown in Figure 4, the drive shaft 20r for the right wheel is inserted into the inner periphery of the small diameter portion 82b of the differential case 82, and the drive shaft 20l for the left wheel is inserted into the opening 82l of the large diameter portion 82a of the differential case 82.

[0029] A spiral groove 82d is provided on the inner peripheral surface of the small diameter portion 82b. The spiral groove 82d is provided in a direction that facilitates the introduction of lubricating oil from the outside to the inside of the differential case 82 in response to the rotation of the right-wheel drive shaft 20r when the vehicle 10 moves forward. The small diameter portion 82b and the spiral groove 82d correspond to the "differential tubular portion" and "groove," respectively, in this invention. In the direction of the third axis C3, the tip end of the small diameter portion 82b of the differential case 82 on the opening 82r side is close to the gap S (see FIG. 3) between the case tubular portion 74t and the right-wheel drive shaft 20r.

[0030] In the direction of the third axis C3, the large diameter portion 82a has openings 82o (see FIG. 3) for discharging the lubricating oil only on the side opposite to the small diameter portion 82b. For example, a plurality of openings 82o are provided at equal angular intervals. The openings 82o correspond to the "openings" in this invention.

[0031] According to this embodiment, the power transmission mechanism 16 includes a main shaft 28 provided with a drive gear 32 that sets the gear position, a differential gear 80 to which power is transmitted from the main shaft 28, and a case 70 that houses the main shaft 28 and the differential gear 80. In the power transmission mechanism 16, (a) the differential gear 80 is disposed above the main shaft 28, and (b) the case 70 has a cylindrical case portion 74t that stores lubricating oil scooped up by the drive gear 32 so that the lubricating oil can be introduced into the differential gear 80. Even when the differential gear 80 is disposed above the main shaft 28 provided with the drive gear 32 that scoops up the lubricating oil, the lubricating oil is stored in the cylindrical case portion 74t of the case 70. As a result, when the case cylindrical portion 74t is present, the lubricating oil stored in the case cylindrical portion 74t is efficiently introduced into the inside of the differential case 82, improving the lubrication of the differential gear 80, compared to when the case cylindrical portion 74t is not present.

[0032] According to this embodiment, the case cylindrical portion 74t is cylindrical and faces the right-wheel drive shaft 20r via a gap S. As a result, the lubricating oil OIL is stored in the gap S, and the lubricating oil OIL is efficiently introduced into the differential case 82.

[0033] According to this embodiment, (a) the differential case 82 has a small diameter portion 82b facing the right wheel drive shaft 20r, and (b) the inner periphery of the small diameter portion 82b is provided with a spiral groove 82d that introduces lubricating oil O from the cylindrical case portion 74t into the inside of the differential case 82 in response to rotation of the right wheel drive shaft 20r. Compared to a case where the spiral groove 82d is not provided, when the spiral groove 82d is provided, the lubricating oil O stored in the cylindrical case portion 74t is more likely to be introduced into the inside of the differential case 82 via the spiral groove 82d in response to rotation of the right wheel drive shaft 20r. This allows the lubricating oil O to be introduced efficiently into the inside of the differential case 82.

[0034] According to this embodiment, the differential case 82 has an opening 82o for discharging the lubricating oil only on the side opposite to the cylindrical case portion 74t side where the lubricating oil is introduced. In the direction of the third axis C3, the lubricating oil is introduced into the differential case 82 from the cylindrical case portion 74t side and discharged from the opening 82o of the differential case 82 provided only on the side opposite to the cylindrical case portion 74t side. In addition, in the radial direction centered on the third axis C3, the lubricating oil is introduced into the differential case 82 from the radially inner peripheral side where the cylindrical case portion 74t is provided and discharged to the radially outer peripheral side where the opening 82o is provided. This allows the lubricating oil to be supplied to the entire interior of the differential case 82 in the differential gear 80.

[0035] The above-described embodiments of the present invention are merely examples, and the present invention can be embodied in various forms with various modifications and improvements based on the knowledge of those skilled in the art without departing from the spirit of the present invention.

[0036] In the above-described embodiment, the inner periphery of the small diameter portion 82b is provided with a spiral groove 82d, but the present invention is also applicable to an embodiment in which the spiral groove 82d is not provided. Even in an embodiment in which the spiral groove 82d is not provided, the lubricating oil OIL can be introduced into the interior of the differential case 82 via the gap S between the inner periphery of the small diameter portion 82b and the outer periphery of the right-wheel drive shaft 20r. Even in such an embodiment, when the cylindrical case portion 74t is provided, the lubricating oil OIL stored in the cylindrical case portion 74t is introduced into the interior of the differential case 82 more efficiently than when the cylindrical case portion 74t is not provided, thereby improving lubrication of the differential gear 80.

[0037] In the above-described embodiment, the large diameter portion 82a has the opening 82o only on the side opposite the cylindrical case portion 74t. However, the present invention is not limited to this. For example, the present invention can also be applied to an embodiment in which the openings 82o are provided on both the side of the large diameter portion 82a opposite the cylindrical case portion 74t and on the cylindrical case portion 74t side. In such an embodiment, the lubricating oil OIL is introduced into the differential case 82 from the cylindrical case portion 74t side in the direction of the third axis C3 and discharged from the openings 82o of the differential case 82. Even in such an embodiment, compared to a case without the cylindrical case portion 74t, when the cylindrical case portion 74t is provided, the lubricating oil OIL stored in the cylindrical case portion 74t is introduced into the differential case 82 more efficiently, thereby improving lubrication of the differential gear 80.

[0038] In the above-described embodiment, the right wheel 14r and the drive shaft 20r for the right wheel correspond to the "drive wheels" and "drive shaft" of the present invention, respectively, and the inner peripheral surface of the tubular case portion 74t faces the outer peripheral surface of the drive shaft 20r for the right wheel across a gap S. However, the present invention is not limited to this. For example, the left wheel 14l and the drive shaft 20l for the left wheel may correspond to the "drive wheels" and "drive shaft" of the present invention, respectively, and the inner peripheral surface of the tubular case portion 74t may face the outer peripheral surface of the drive shaft 20l for the left wheel across a gap.

[0039] In the above-described embodiment, the "reservoir" of the present invention is the cylindrical case portion 74t, but the present invention is not limited to this. The "reservoir" of the present invention does not necessarily have to be cylindrical as long as it has the function of storing the lubricating oil scooped up by the drive gear 32 for introduction into the differential gear 80. For example, in the above-described first embodiment, a slit extending in the direction of the third axis C3 may be formed in the lower part of the cylindrical case portion 74t.

[0040] In the above embodiment, the vehicle 10 is an FR vehicle, but the present invention is also applicable to FF (Front Engine Front Drive) vehicles, MR (Midship Engine Rear Drive) vehicles, and four-wheel drive vehicles. [Explanation of symbols]

[0041] 14r: right wheel (drive wheel), 16: power transmission mechanism, 20r: right wheel drive shaft (drive shaft), 28: main shaft (shaft), 32: drive gear (gear), 70: case, 74t: case cylindrical portion (storage portion), 80: differential gear, 82: differential case, 82b: small diameter portion (differential cylindrical portion), 82d: spiral groove (groove), 82o: opening (opening), OIL: lubricating oil, S: gap

Claims

1. A power transmission mechanism including: a shaft provided with a gear that sets a gear position; a differential gear to which power is transmitted from the shaft; and a case that accommodates the shaft and the differential gear, The differential gear is disposed above the shaft, The case has a reservoir for storing lubricating oil scooped up by the gears so that the lubricating oil can be introduced into the differential gear. A power transmission mechanism characterized by:

2. The storage portion is cylindrical and faces a drive shaft that connects the differential gear and the drive wheels via a gap.

2. The power transmission mechanism according to claim 1.

3. a differential case of the differential gear having a differential cylindrical portion facing the drive shaft, The inner periphery of the differential cylinder portion is provided with a groove that introduces the lubricating oil from the reservoir into the inside of the differential case in response to rotation of the drive shaft.

3. The power transmission mechanism according to claim 1 or 2.

4. The differential case of the differential gear has an opening for discharging the lubricating oil only on the side opposite to the reservoir side where the lubricating oil is introduced.

3. The power transmission mechanism according to claim 1 or 2.

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