VENTILATION STRUCTURE IN POWER UNIT

Abstract

A unit housing C comprises an oil supply channel 17, 90 for supplying a portion of oil in a gear mechanism chamber 10 to a bearing of an engine output shaft 26, an oil return channel 16 for returning the oil from an engine compartment 20 to the gear mechanism chamber, and a partition 12s, one side surface of which faces the gear mechanism chamber and the other side surface faces the engine compartment. One side surface of the partition 12s and a cover 80 coupled to that side surface define a vent chamber 60, which is shielded from the gear mechanism chamber 10. An inlet 60i of the vent chamber is open to the other side surface of the partition 12s and communicates with the engine compartment. This prevents oil dispersed by each gear of the gear mechanism within a gearbox housing from entering the vent chamber, thereby reducing the risk of oil splashing out of the vent chamber.Since the vent chamber is defined by one surface of the partition wall of the gearbox housing and the attached cover, a hollow structure of the vent chamber, which is separate from the gearbox mechanism chamber, can be easily obtained without the complication of a partition wall structure and a molding process.

Description

TECHNICAL AREA

[0001] The present invention relates to a venting structure in a power unit, in particular a power unit comprising a motor and a transmission device which receives an output of the motor, wherein the transmission device comprises a gear transmission mechanism which is capable of transmitting the output of the motor to a drive shaft, and a transmission housing which includes a transmission mechanism chamber which receives the gear transmission mechanism, wherein the transmission housing and a motor housing form a unit housing of the power unit. BACKGROUND STATE OF THE ART

[0002] The power unit described above is known as disclosed, for example, in patent document 1 below, and a gearbox housing is provided therein with a vent chamber. DOCUMENTS ON THE STATE OF TECHNOLOGY PATENT DOCUMENTS

[0003] Patent document 1: Unexamined Japanese patent application no. 2017-161000 SUMMARY OF THE INVENTION PROBLEMS TO BE SOLVED BY THE INVENTION

[0004] In the power unit described in patent document 1, a device is attached to an arrangement section of an inlet (50a) of the vent chamber to prevent oil, which has been injected into the gearbox housing by each gear of the gear mechanism, from entering the vent chamber. However, the inlet of the vent chamber is open directly to the interior of the gearbox housing and is located relatively close to a gear (37), which is a section of the gear mechanism. Therefore, it is not possible to reliably prevent the oil sprayed by the gear (37) from entering the vent chamber.

[0005] The present invention has been proposed in light of the above considerations. One objective of the present invention is to provide a venting structure in a power unit that can solve the problem described above in conventional devices. MEANS TO SOLVE THE PROBLEMS

[0006] To achieve the above-described objective, the present invention has a first feature of providing a venting structure in a power unit, wherein the power unit comprises a motor and a transmission device configured to receive an output from the motor, wherein the transmission device comprises a gear transmission mechanism capable of transmitting the output of the motor to a drive shaft, and a transmission housing comprising a transmission mechanism chamber that accommodates the gear transmission mechanism, wherein the transmission housing and a motor housing for the motor form a unit housing of the power unit, wherein the unit housing comprises an oil supply channel configured to supply at least one bearing of a motor output shaft with a portion of oil lubricating the gear transmission mechanism, and an oil return channel configured toa return oil from an engine compartment within the engine housing to the transmission mechanism chamber, and comprises a partition, one side surface of which faces the transmission mechanism chamber and the other side surface faces the engine compartment, wherein one side surface of the partition and a cover coupled to that side surface define a vent chamber which is shielded from the transmission mechanism chamber and which is open to atmospheric air, and wherein the vent chamber comprises an inlet which is open to the other side surface of the partition and which communicates with the engine compartment.

[0007] In addition to the first feature, the present invention has a second feature in which the gear transmission mechanism comprises, at an output side of a gear transmission path, a final output gear which is configured to transmit a rotary driving force to the drive shaft, and which, viewed from an axial direction of the final output gear, overlaps at least a section of the vent chamber with the final output gear.

[0008] In addition to the first or the second feature, the present invention has a third feature in which the gear transmission mechanism comprises a counter gear on the gear transmission path and, looking radially outwards from an axis of rotation of the counter gear, at least a section of the vent chamber overlaps with the counter gear.

[0009] In addition to each of the first to third features, the present invention has a fourth feature in which the other side surface of the partition is provided with a projecting wall which projects towards the engine compartment and surrounds the inlet of the vent chamber.

[0010] In addition to each of the first to fourth features, the present invention has a fifth feature in which the inlet of the vent chamber faces a stator which is fixed inside the motor housing. EFFECTS OF INVENTION

[0011] According to the first feature, in the power unit comprising the engine and the transmission device, the unit housing includes the oil supply channel, which is configured to supply at least one bearing of the engine output shaft with the portion of the oil lubricating the gear mechanism; the oil return channel, which is configured to return oil from the engine compartment to the transmission mechanism chamber within the transmission housing; and the partition, one side surface of which faces the transmission mechanism chamber and the other side surface faces the engine compartment, wherein one side surface of the partition and the cover coupled to that one side surface define the vent chamber, and the vent chamber includes the inlet which is open to the other side surface of the partition and which communicates with the engine compartment.Accordingly, since the inlet of the breather chamber is not directly open to the gearbox mechanism chamber and communicates with it via the engine compartment, it is effectively prevented that oil scattered by each gear of the gearbox mechanism within the gearbox housing enters the breather chamber. This reduces the risk of oil splashing out of the breather chamber. Furthermore, because the breather chamber is defined by one side surface of the gearbox housing partition and the cover coupled to that side surface, it is possible to easily create a hollow breather chamber structure that is separate from the gearbox mechanism chamber without complicating the structure of the gearbox housing partition and its forming process, thus contributing to cost reduction.

[0012] According to the second feature, since the gear mechanism on the output side of the gear path includes the final output gear, which is designed to transmit the rotary driving force to the drive shaft, and since, viewed from an axial direction of the final output gear, at least the section of the vent chamber overlaps with the final output gear, it is possible to prevent the vent chamber from projecting strongly axially outwards towards the final output gear, and this is advantageous in making the gearbox housing radially more compact.

[0013] According to the third feature, since the gear mechanism includes the mating gear on the gear path and, looking radially outwards from the axis of rotation of the mating gear, at least the section of the vent chamber overlaps with the mating gear, it is possible to prevent the vent chamber from protruding significantly towards an axially outer side with respect to the mating gear, and this is advantageous in making the gearbox housing axially more compact.

[0014] According to the fourth feature, since the other side surface of the partition is provided with the projecting wall which extends towards the engine compartment and surrounds the inlet of the vent chamber, even if the oil is slightly scattered within the engine compartment, it is possible to effectively prevent the scattered oil within the engine compartment from entering the vent chamber by using the projecting wall.

[0015] According to the fifth feature, since the inlet of the vent chamber faces the stator, which is fixed inside the motor housing, the inlet of the vent chamber faces the stator, which does not rotate inside the motor compartment, thus preventing the oil from entering the vent chamber through the motor compartment more effectively by using the stator. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 is a sectional view of an embodiment of a power unit according to the present invention, in which a cross-section extending through the axes of rotation of an input gear and a mating gear is viewed from below (sectional view along line 1X-1X in Fig. 2). Fig. Figure 2 is a side view of the power unit, viewed from the left, in a state where the first housing half of a gearbox housing and the bearings attached to it are omitted (cross-sectional view along line 2X-2X in Fig. 1). Fig. 3 is a left-side view of the power unit in a state in which, in addition to the one in Fig. In the second shown state, a differential housing and a final output gear are omitted (cross-sectional view along line 3X-3X in Fig. 1). Fig. 4 is a side view of the power unit from the left side, in which, in addition to the one in Fig. In the state shown in Figure 3, an intermediate housing is omitted (cross-sectional view along line 4X-4X in Figure 3). Fig. 1). Fig. Figure 5 is a sectional view showing a main section of a vent and a first oil collection part (enlarged sectional view along line 5X-5X in Fig. 3). Fig. Figure 6 is a top-down sectional view of the interior of the vent in a cross-section along its longitudinal direction (enlarged sectional view along line 6X-6X in Fig. 4). Fig. Figure 7 is an enlarged perspective view of the breather and the first oil collection part in a state in which the first housing half and the intermediate housing are removed from a second housing half (from an arrow 7X in Fig. 4 (perspective view considered). Fig. Figure 8 is a sectional view showing the arrangement of a second oil supply channel in an engine housing (sectional view along line 8X-8X in Fig. 4). Fig. Figure 9 is a right-hand view, viewed from the side where the motor is located, of a main section of the second housing half in a state where the motor housing is omitted (representation of an arrow 9 in Fig. 1). Fig. Figure 10 is a perspective view showing a vent inlet on a side surface of the second housing half on the side where the engine is located, and the vicinity of an opening of a first oil supply channel (from an arrow 10X in Fig. 9 (enlarged perspective view). Fig. Figure 11 is an enlarged section view along the line 11X-11X in Fig. 3. EXPLANATION OF REFERENCE SYMBOLS BM1, BM2 engine mounts C Unit housing cm engine housing CT gearbox housing G Gear mechanism GF final output gear Gi input gear Gc counter gear M Motor PU power unit T Gearbox device Xc axis of rotation of the mating gear 10 Gear mechanism chamber 12s partition 12si, 12so left surface, which serves as one side of the partition right surface, which serves as the other side of the partition 12t protruding wall 16 Oil return channel 17 first oil supply channel as an oil supply channel 20 Engine compartment 24 Stator 26 Motor output shaft 51, 52 Drive shafts 60 Vent chamber 60i Inlet of the vent chamber 90 second oil supply channel as one oil supply channel MODE FOR EXECUTING THE INVENTION

[0016] Firstly, it includes in Fig. 1 to Fig. 4. A power unit PU mounted in a vehicle, for example an automobile, comprises an electric motor M as a power source and a transmission device T, which transmits an output of the motor M to a left and a right drive wheel. A metal unit housing C of the power unit PU is fixed and held on a suitable section of a vehicle body and includes a transmission housing Ct, which serves as an outer casing of the transmission device T, and a motor housing Cm, which serves as an outer casing of the motor M.

[0017] Within a space inside the gearbox housing Ct, i.e., in a gearbox mechanism chamber 10, a reduction device R, which slows down the output of the motor M, and a differential device D are arranged. The differential device D distributes one output of the reduction device R to a left and a right drive shaft 51, 52 (and thus to a left and a right drive wheel, which mesh with the shafts 51, 52 and rotate), while enabling differential rotation.

[0018] In the description and drawings, the directions front-back, left-right, top-down refer to the directions front-back, left-right, top-down in a state in which the power unit PU is installed in the vehicle.

[0019] The motor housing Cm is configured such that it integrally comprises an outer end wall 21 and a tubular outer circumferential wall 22, which transitions into an outer circumferential section of the outer end wall 21, and has a shell-like body that is open towards the gearbox housing Ct. Within a space inside a motor housing Ct, i.e., in a motor chamber 20, are arranged a circular annular stator 24, which is fixed to an inner circumferential wall of the outer circumferential wall 22 of the motor housing Cm and which is wound in its circumferential direction by a plurality of coil groups 23 at intervals between them; a rotor 25, which includes a magnet (not shown) and which interacts with the stator 24 to generate a rotary driving force; and a motor output shaft 26, which fixes the rotor 25 to the outer circumferential section.Both end sections of the motor output shaft 26 are mounted on the gearbox housing Ct and the motor housing Cm, respectively, via a pair of motor bearings Bm1 and Bm2. Furthermore, in this embodiment, the motor output shaft 26 is hollow, and a drive shaft 52 extends vertically through a hollow section of the motor output shaft 26 on one right side.

[0020] The gearbox housing Ct is arranged such that it is divided on a left and a right side into a first and a second housing half-body 11, 12, which are detachably coupled to each other. The first housing half-body 11, which is located on the left side, comprises a side wall 11s, which covers left sections of the reduction device R and the differential device D, and a tubular outer circumferential wall 11o, which is continuously provided on an outer circumferential section of the side wall 11s and covers the outer circumferential sides of the reduction device R and the differential device D.

[0021] The second housing half-body 12 on the right side comprises a tubular outer circumferential wall 12o, which covers the outer circumferential side of the reduction device R, and a partition wall 12s, which is integrally and continuously provided around an inner circumferential section of an axial intermediate section of the outer circumferential wall 12o and which covers a right section of the reduction device R. Furthermore, the partition wall 12s acts as a partition separating the engine compartment 20 from the transmission mechanism chamber 10. A left surface 12si, which is one side surface of the partition wall 12s, faces the transmission mechanism chamber 10, and a right surface 12so, which is the other side surface, faces the engine compartment 20.

[0022] The facing end surfaces of the outer circumferential walls 11o, 12o of the first and second housing halves 11, 12 are detachably connected to one another by a plurality of bolts b1, and a sealing element (in this embodiment a liquid seal) for sealing a gap between the facing end surfaces is inserted between them. The facing end surfaces of the outer circumferential wall 12o of the second housing half 12 and the outer circumferential wall 22 of the motor housing Cm are detachably connected to one another by a plurality of bolts b2, and a sealing element (in this embodiment a liquid seal) for sealing a gap between the facing end surfaces is inserted between them.

[0023] A lower part within the gearbox housing Ct functions as an oil reservoir 15, which stores oil for lubrication. An oil surface L of the oil stored in the oil reservoir 15 is set to a level such that a lower section of a final output gear Gf described below is immersed in and in contact with the stored oil when the motor M (i.e., the reduction gear R and the differential gear D) is stopped (see Fig. 2 to 4).

[0024] In a lower section of the partition 12s of the second housing half 12, an oil return channel 16 is formed, which returns oil from the engine compartment 20 to the transmission mechanism chamber 10 in order to pass through it. The engine compartment 20 and the transmission mechanism chamber 10 communicate with each other via the oil return channel 16.

[0025] Next, an example of the reduction device R will be given with reference to mainly Fig. 1 to Fig. 4 described.

[0026] A transmission mechanism G, which is formed from a transmission train and functions as the reduction device R, comprises, for example, an input gear Gi, which (in the embodiment by a splined connection and a retaining ring) is fixed to an outer circumference of an inner end section of the motor output shaft 26, which curves into the transmission mechanism chamber 10; a countershaft 14, which is located on a rear upper side relative to an axis of rotation Xi of the input gear Gi and which includes an axis of rotation Xc parallel thereto; a countershaft Gc, which is fitted onto and fixed to the countershaft 14 (in the embodiment by a splined connection and a retaining ring) in order to mesh with the input gear Gi; a counter pinion Gcp, which (in the embodiment integrally) is fixed to an outer circumference of the countershaft 14 in a position spaced to the left of the countershaft Gc;and a final output gear Gf, which is arranged on a coaxial line relative to the input gear Gi, which has a larger diameter than the mating gear Gcp and which meshes with the mating gear Gcp.;

[0027] In this embodiment, the final output gear Gf is arranged such that it engages with the mating pinion Gcp in a specific semicircular area (right semicircular area with respect to the axis of rotation Xi). Fig. 2) meshes, in which a tooth surface meshes in accordance with a forward rotation of the final output gear Gf (rotation in one direction counterclockwise in Fig. 2) moved from a lower end of the final output gear Gf to an upper end thereof.

[0028] One end section of the countershaft 14 is rotatably mounted on the side wall 11s of the first housing half-body 11 via the first counter bearing Bc1, and the other end section of the countershaft 14 is rotatably mounted on the partition wall 12s of the second housing half-body 1 via the second counter bearing Bc2. In particular, in the embodiment as shown Fig. As can be seen in Figure 1, the first counter bearing Bc1 is formed from a shielded bearing.

[0029] That is, similar to conventionally known shielded bearings, the first counter bearing Bc1 comprises an outer running ring 101 and an inner running ring 102, each having a circular ring shape, a plurality of balls 103 which are inserted between the mutually facing circumferences of both running rings 101, 102, and a resin or metal shield 104 which has a circular ring plate shape and which is located in an axial direction between an end (right end) of the outer running ring 101 and an end (right end) of the inner running ring 102. The shield 104 is fixed to one of the inner running ring 101 and the outer running ring 102 (for example, the outer running ring 101) and is adjacent to the other of the inner running ring 101 and the outer running ring 102 (for example, the inner running ring 102) at a small distance and facing it.

[0030] As the first counter bearing Bc1, a sealed bearing (which is conventionally known but not shown) can be used instead of the shielded bearing described above. In this sealed bearing, a contact seal made of rubber or synthetic resin is used instead of the non-contact shield 104 described above. This contact seal is fixed to one of the inner and outer races 101, 102 (for example, the outer race 101) and is in sliding contact with the inner and outer races 101, 102 (for example, the inner race 102).

[0031] In particular, in the embodiment a left side of the shielded bearing or the sealed bearing, which serves as the first counter bearing Bc1, is open, thereby enabling the shielded bearing or the sealed bearing to be lubricated with an oil which flows from a right end side of the counter shaft 14 to a left end side through its hollow section.

[0032] The gears Gi, Gc, Gcp, Gf of the gear mechanism G are each formed from helical gears. Fig. For simplicity, the helical teeth of each helical gear are shown in a section along their tooth path. The final output gear Gf functions as a large-diameter gear and is concentrically mounted on an outer circumferential section of a differential housing Dc described below and fixed by a suitable fastening means (for example, a screw coupling, welding, or the like).

[0033] During operation of the reduction gear R, a primary deceleration occurs between the two gears Gc and Gi due to the larger diameter of the mating gear Gc compared to the input gear Gi. A secondary deceleration occurs between the two gears Gf and Gcp due to the larger diameter of the final output gear Gf compared to the mating gear Gcp. It should be noted that the mating gear Gc and the mating pinion Gcp can be integral components.

[0034] Furthermore, when the motor M rotates in a forward direction to propel a vehicle forward, each of the gears Gi, Gc, Gcp, Gf described above rotates in the forward direction in conjunction with this rotation. The forward direction is indicated by hollow arrows in Fig. 2 and Fig. Figure 4 shows that in this case, the forward direction of rotation of the input gear Gi and the final output gear Gf is the same as the forward direction of rotation of the motor M, and a forward direction of rotation of the mating gear Gc and the mating pinion Gcp is a direction opposite to the forward direction of rotation of the motor M.

[0035] The mating pinion Gcp and the final output gear Gf are arranged such that, during the forward rotation of these gears, in accordance with the mutual engagement between the mating pinion Gcp and the final output gear Gf, the oil on the tooth surface is forced from a meshing section 40 to one side (in the embodiment, the left side) in an axial direction of the mating pinion Gcp. This arrangement obviously involves a helix angle of the helical gear teeth (i.e., an orientation of the tooth track) which has a helical shape with respect to an axis of both the mating pinion Gcp and the final output gear Gf.

[0036] Furthermore, according to the arrangement of the counter pinion Gcp and the final output gear Gf described above, in accordance with the movement of the engagement position from a right end to a left end in an axial direction of the teeth when the gears mesh, the oil is forced at the tooth surface from the engagement section 40 to an axially left side in a preloaded manner, as indicated by a dashed arrow in Fig. 1 shown.

[0037] In contrast, in this embodiment, the first counter bearing Bc1, which in this embodiment comprises a shielded bearing, is used as a fluid boundary wall that counteracts the oil pushed towards the axially left side by the engagement section 40 described above, in order to prevent the forced oil from flowing towards the axially left side. In this case, as shown in Fig. As can be seen in Figure 1, the first counter bearing Bc1 is arranged adjacent to the axially left end faces of the teeth of the counter pinion Gcp and is formed in such a way that tooth tip sections of the left end faces of the teeth can be covered (i.e. a larger diameter than that of the counter pinion Gcp).

[0038] Furthermore, in the embodiment, the axial width of the counter pinion Gcp is defined such that a tooth section of the counter pinion Gcp has a specific length s (see Fig. 1) which extends to the axially left side relative to the engagement section 40 with the final output gear Gf. Instead of this setting, another embodiment may also be possible in which the length s of the tooth section of the counter pinion Gcp, which extends from the engagement section 40 described above to the axially left side, is set to zero or a negligible length.

[0039] Next, the differential device D will be discussed mainly with reference to the Fig. 1 and Fig. 2 described. The differential device D comprises the differential housing Dc, which integrally includes bearing hub parts Dca, Dcb at both axial end sections of a body part of the differential housing Dc; and a differential gear mechanism Dg, which is received in the body part of the differential housing Dc and which transmits a rotational force of the differential housing Dc to the pair of drive shafts 51, 52 while enabling differential rotation.

[0040] The bearing hub part Dca on a left side of the differential housing Dc is supported by a first differential bearing Bf1 on the side wall 11s of the first housing half 11, and the bearing hub part Dcb on a right side of the differential housing Dc is supported by a second differential bearing Bf2 on an intermediate housing 80 described below, which is fixed to the partition 12s of the second housing half 12. The first and second differential bearings Bf1, Bf2 are an example of a pair of bearings for a final output gear.

[0041] Furthermore, the differential housing Dc is rotatably mounted on the gearbox housing Ct on the axis of rotation Xi of the input gear Gi. Parallel to this, the drive shafts 51, 52, which are rotatably fitted onto the inner circumferences of the left and right bearing hub sections Dca, DCB of the differential housing Dc, are also mounted on the gearbox housing Ct via the gearbox housing Ct and the first and second differential bearings Bf1, Bf2. Additionally, an intermediate section of the right drive shaft 52 is mounted on the motor housing Cm via a bearing Bd.

[0042] A helical groove is formed in a mating surface of the bearing hub part Dca on the left side and the drive shaft 51 and a mating surface of the bearing hub part Dcb on the right side and the drive shaft 52, which is capable of providing a screw pumping action to guide oil scattered within the gearbox housing Ct into the differential housing Dc.

[0043] On an outer circumference of the body part of the differential housing Dc, the final output gear Gf, which includes a toothed ring (in the embodiment with the bolt b4), is fixed in a position offset to the axially right side of a central section of the body part. Furthermore, the differential housing Dc includes two or more window sections Dch (two in the embodiment) in the body part, which are positioned to the axially left side relative to the final output gear Gf. The window sections Dch are arranged symmetrically, with a pinion shaft 33 positioned between them, and function as an operating opening for gear assembly or as an oil inlet opening between an outer and an inner side of the differential housing Dc.

[0044] From the relationship in which the window sections Dch are arranged in a manner offset to the axially left side relative to the final output gear Gf, the axial position of the window sections Dch is such that it partially coincides with the tooth section of the mating pinion Gcp, which extends to the axially left side of the engagement section 40 with the final output gear Gf, as shown from Fig. 1 is evident.

[0045] Although one example of the differential housing Dc is integrally configured in the embodiment, the differential housing Dc can be configured such that it is divided into two or more housing elements which are mutually coupled.

[0046] Next, the differential gear mechanism Dg is described. The differential gear mechanism Dg comprises a pair of lateral gears 31, which are received in the differential housing Dc and which are rotatable about the same axis as the differential housing Dc; two or more pinions 32, which mesh with both lateral gears 31; and the pinion shaft 33, which is fixed to the differential housing Dc and which rotatably supports the pinions 32 about their axis perpendicular to the axis of rotation of the lateral gears 31. An inner circumference of a central hole of each of the left and right lateral gears 31 is locked and coupled to an outer circumference of an inner end section of each of the first and second drive shafts 51, 52 (in this embodiment by a splined connection).

[0047] The structure and function of the differential gear D are generally known, and therefore a further description is omitted. However, the rotary drive force from the motor M is introduced through the reduction device R and then from the final output gear Gf into the differential housing Dc, and the differential device D distributes and transmits the rotary drive force to the first and second drive shafts 51, 52, while enabling differential rotation.

[0048] The unit housing C (in particular the gear housing Ct) comprises a first oil collection section H1, which is capable of collecting oil scattered from the input gear Gi; an input gear cover 70, which includes an upwardly open rear portion that allows the mating gear Gc and the input gear Gi to mesh with each other, and which covers the input gear Gi; and a vent BR, which allows an interior of the unit housing C to communicate with the outside air while preventing oil from splashing out into the outside air. Next, specific structures of the first oil collection section H1, the input gear cover 70, and the vent BR are described with reference to Fig. 5 to Fig. 11 described.

[0049] As from Fig. As can be seen in Figure 4, the first oil collection section H1 has an oil inlet opening H1i on its front side, aligned with the forward direction of rotation of the input gear Gi along a common tangent of the pitch circles of the input gear Gi and the mating gear Gc in a side view (i.e., viewed from the axial direction of the input gear Gi). Accordingly, after the input gear Gi, which rotates at high speeds together with the motor M, meshes with the mating gear Gc, the oil remaining on the tooth surface is forcefully sprayed upwards due to centrifugal force in the direction of the common tangent described above and moves into the oil inlet opening H1i, so that the oil is efficiently collected by the first oil collection section H1.The oil collected by the first oil collection part H1 can be supplied to a lubrication target part, which is located in both the gearbox housing Ct and the motor housing Cm, as described below.

[0050] On the other hand, the input gear cover 70 includes the rear, upwardly open part, which enables mutual engagement between the mating gear Gc and the input gear Gi, and has an inner space, a lower section of which functions as an auxiliary oil reservoir 71, capable of storing oil for the input gear Gi. In an upper section of the inner space of the input gear cover 70 is the first oil collection part H1, and the opening, i.e., the oil inlet opening H1i, faces a meshing section in which the mating gear Gc and the input gear Gi mesh with each other.

[0051] The first oil collection part H1 described above, the input gear cover 70 and the vent BR are formed by the second housing half-body 12 and the intermediate housing 80, which serves as a cover detachably coupled to the partition 12s.

[0052] In a more detailed description of how they are made Fig. As can be seen in Figure 4, the left surface 12si of the partition 12s is integrally provided with an upper arc-shaped W1 surrounding the input gear, which surrounds the input gear Gi over half its circumference or more; a wall W2 forming the oil collection part, which extends slightly downwards from an upper inner circumference of the wall W1 surrounding the input gear and continues in a circumferential direction of the input gear Gi, while changing its direction to a side on which the mating gear Gc is located; a wall W3 forming the vent chamber, which is spaced upwards from the wall W1 surrounding the input gear and which extends substantially along an inner circumference of the outer circumferential wall 12o of the second housing half-body 12;and a wall W4 forming a communication channel, which is located directly below the wall W3 forming the vent chamber and integrally connects a front section of the wall W1 surrounding the input gear with a front part of the outer circumferential wall 12o of the second housing half-body 12. Each front end face (left end face) of the wall W1 surrounding the input gear, the wall W3 forming the vent chamber, and the wall W4 forming the communication channel is on the same plane as the corresponding matching face of the outer circumferential wall 11o of the first housing half-body 11 and the outer circumferential wall 12o of the second housing half-body 12.

[0053] In particular, the wall W1 surrounding the input gear is continuously provided with a projecting portion W1a, which extends upwards from its lower open end, thereby preventing oil from flowing out of the auxiliary oil reservoir 71. Furthermore, the wall W1 surrounding the input gear includes, at an inner circumferential edge of the front end face (left end face), a positioning step section W1s, which extends circumferentially and which is recessed by a step that is deeper than the front end face.

[0054] On the other hand, the intermediate housing 80 comprises a disk-shaped housing body 81, which corresponds to the wall W1 surrounding the input gear, and an upwardly projecting section 82, which is provided continuously and integrally on a section of an upper half of the housing body 81 and which extends upwards in a substantially fan-like manner. On an outer surface (left side) of the housing body 81, a stepped cylindrical annular hub portion 81b is integrally provided in a projecting manner and appropriately secures an outer race of the second differential bearing Bf2 on the right side. The housing body 81 includes on its inner surface (right side) an upper arc-shaped projection 81a, which is provided in a section closer to an outer circumferential section of the housing body 81.The upper arc-shaped projection 81a is integrally provided in a projecting manner such that it extends along the wall W1 surrounding the input gear and is adaptable to the positioning stage section W1s.

[0055] The left end face of the outer circumferential wall 12o of the second housing half-body 12 is shaped such that the section corresponding to the wall W3 forming the vent chamber has a greater width. As shown in the Fig. 2 to Fig. As can be seen in Figure 4, an end surface of the greater width has a shallow groove 12g which extends along an upper edge of the upwardly projecting section 82 and which is adjacent to the upwardly projecting section 82. A section of a sealing element (e.g., a liquid seal) to be used between the connecting end surfaces of the first and the second housing half-body 11, 12 can be held in the groove 12g.

[0056] The intermediate housing 80 is fixed to the partition 12s of the second housing half-body 12 by allowing the arc-shaped projection 81a described above to fit onto the positioning step section W1s of the wall W1 surrounding the input gear (see Fig. 1, Fig. 5) and by coupling an inner surface of the outer circumferential section of the housing body 81 with the wall W1 surrounding the input gear on an outer side of the arc-shaped projection 81a (see Fig. 1, Fig. 3, Fig. 5 and Fig. 6) with a bolt b3. In such a fixed state of the intermediate housing 80, the input gear cover 70 is defined by the intermediate housing 80 and the partition 12s (in particular by an inner circumference of the wall W1 surrounding the input gear, the left surface 12si of the partition 12s and an inner surface of the housing body 81).

[0057] Furthermore, in the fixed state of the intermediate housing 80 described above, an upper surface (right end surface) of the arc-shaped projection 81a of the inner surface of the housing body 81 faces adjacent to the front end surface (left end surface) of the wall W2 forming the oil collection section. Accordingly, the first oil collection section H1 is defined by the housing body 81 and the partition 12s (in particular, the wall W2 forming the oil collection section and the left surface 12si of the partition 12s).

[0058] In this embodiment, the front end surfaces (left end surfaces) of the projecting part W1a and the wall W2 forming the oil collection part are adjacent to each other and facing each other with a small gap (for example, 0.5 millimeters) relative to the inner surface of the housing body 81, but can abut the inner surface of the housing body 81.

[0059] As from Fig. As can be seen in Figure 4, the second housing half 12 of the gearbox housing Ct includes a second oil collection element H2, which is located on a front side in the forward direction of rotation of the mating gear Gc relative to the first oil collection element H1 and is capable of collecting the oil scattered by the mating gear Gc. The second oil collection element H2 is formed from a concave surface located on the left surface 12si of the partition 12s in an area between the breather BR and a front section of the mating gear Gc in the front-to-back direction, and between a front section of the outer circumferential wall 12o of the second housing half 12 and the front section of the wall W1 surrounding the input gear in the top-to-bottom direction. The opening at a rear end of the second oil collection element H2 serves as an oil inlet H2i, which is adjacent to and facing the front section of the mating gear Gc.Furthermore, the second oil collection part H2 has a front end section which communicates directly with a rear end of a first communicating oil channel 91 described below.

[0060] In a section of the partition 12s forming a side wall section of the first oil collection part H1, a first oil supply channel 17 is formed in a through-hole shape such that it directs a portion of the oil collected by the first oil collection part H1 to a surrounding section of a first engine bearing Bm1 on the left side. As can be seen from the Fig. 9 and Fig. As can be seen in Figure 10, an open end of the first oil supply channel 17, which is open towards the engine compartment 20 (i.e., a side on which the right surface 12so of the partition 12s is located), is in a position corresponding to a cut-out slot 18s provided in a stepped cylindrical annular projection 18, which is provided on the right surface 12so in a projecting manner and which appropriately secures an outer bearing race of the first engine bearing Bm1. The right surface 12so includes a shallow oil groove 19 provided in a recessed manner, which extends radially inwards from the open end of the first oil supply channel 17 through the slot 18s.

[0061] As described above, the portion of the oil collected by the first oil collection part H1 passes through the first oil supply channel 17 and is guided via the slot 18s and the oil groove 19 to the first engine bearing Bm1.

[0062] On the other hand, the intermediate housing 80 includes a third oil supply channel 85, which directs the portion of the oil collected by the first oil collection part H1 to a surrounding part of the second differential bearing Bf2. As shown from Fig. 3 and Fig. As can be seen in Figure 11, the third oil supply channel 85 is formed from a slot-like through-hole, which extends radially over the arc-shaped projection 81a described above on the inner surface (right side) of the housing body 81 and which penetrates the housing body 81 axially. As described above, the portion of the oil collected by the first oil collection part H1 flows through the third oil supply channel 85 and flows along outer circumferential sections of the second differential bearing Bf2 and the second drive shaft 52.

[0063] As from the Fig. 4 and Fig. As can be seen in Figure 7, the first oil communication channel 91 is defined between the second housing half-body 12 and the intermediate housing 80 and extends in the front-to-back direction, running between the wall W3 forming the vent chamber and a front section of the wall W1 surrounding the input gear and the wall W4 forming the communication channel. On the first oil communication channel 91, a through-flow oil channel 12sh, which penetrates the partition wall 12s in the front-to-back direction, has an open front end and a rear end that opens to an innermost section located at a front face of the first oil collection part H1.

[0064] Accordingly, with the exception of the oil flowing towards the first and third oil supply channels 17, 85, the oil collected by the first oil collection section H1 flows through the through-flow oil channel 12sh into a section of the first communicating oil channel 91. The first communicating oil channel 91 communicates with a second communicating oil channel 92, which is provided axially on the outer circumferential wall 12o of the second housing half-body 12. As can be seen from Fig. As can be seen in Figure 8, the second communicating oil channel 92 communicates with the second engine mount Bm2 on the right side via a series of first and second communicating oil channels 93, 94, which extend in the outer and inner circumferential wall 21, 22 of the engine housing Cm.

[0065] Furthermore, the through-flow oil passage 12sh, the first communicating oil channel (in particular a front half-section), the second communicating oil channel 92, and the first and second communicating oil channels 93, 94, which are connected in series, work together to form a second oil supply channel 90, which carries the portion of the oil collected by the first oil catch section H1 to the second engine mount Bm2 on the right side. A section in the second oil supply channel 90 and the second oil catch section H2 described above communicate with each other via a rear section of the first communicating oil channel 91. Accordingly, the oil collected by the second oil catch section H2 is also carried via the second oil supply channel 90 to the second engine mount Bm2.

[0066] In the fixed state of the intermediate housing 80 described above, a vent chamber 60 of the vent BR is defined by the intermediate housing 80 and the second housing half-body 12 (in particular by an upper surface of the wall W3 forming the vent chamber, a lower surface of a wider front section of the outer circumferential wall 12o of the second housing half-body 12, the left surface 12si of the partition 12s and an inner surface of the upwardly projecting section 82).

[0067] The vent chamber 60 is shielded from the transmission mechanism chamber 10 by the intermediate housing 80 and communicates with the outside air via an outlet cylinder 61 fixed to the front section of the outer circumferential wall 12o of the second housing half-body 12. Similar to conventionally known vents, the vent chamber 60 comprises, on its inner wall (particularly on the left surface 12si of the partition 12s), two or more deflector plates 62, which are arranged in a manner described above to form a labyrinth within the vent chamber 60 and to prevent oil from splashing out (see Figure 1). Fig. 4, Fig. 6 and Fig. 7).

[0068] As from Fig. As can be seen in Figure 6, a communication channel 63, which enables communication between the ventilation chamber 60 and the engine compartment 20, is formed such that it axially penetrates the partition 12s. An opening of the communication channel 63 is open towards the right surface 12so of the partition 12s and forms an inlet 60i of the ventilation chamber 63 facing the engine compartment 20.

[0069] The vent chamber 60 is in a communication state, allowing it to communicate with the engine compartment 20 (and thus the transmission mechanism chamber 10) via the inlet 60i. Accordingly, when the air pressure in the engine compartment 20 is higher than atmospheric pressure, the air in the vent chamber 60 flows from the inlet 60i through the connecting channel 63 and is discharged to the outside air via the exhaust cylinder 61.

[0070] As from the Fig. 6, Fig. 9 and Fig. As can be seen in Figure 10, the right surface 12so of the partition 12s in this embodiment is provided with a projecting wall 12t, which extends towards the engine compartment 20 and surrounds the inlet 60i of the vent chamber 60. Even if the oil is slightly scattered within the engine compartment 20, the provision of the projecting wall 12t effectively prevents the scattered oil from entering the vent chamber 60.

[0071] As from Fig. As can be seen in Figure 2, at least one section of the vent chamber 60 is arranged such that, viewed from an axial direction of the final output gear Gf, it overlaps the final output gear Gf. Since such an arrangement can prevent the vent chamber 60 from projecting significantly outwards axially towards the final output gear Gf, it is advantageous for making the gearbox housing Ct (and thus the unit housing C) more radially compact.

[0072] Fig. Figure 1 clearly shows an arrangement in which the mating gear Gc is positioned axially between the intermediate housing 80 and the partition 12s. From this arrangement, it is evident that the vent chamber 60, defined between the intermediate housing 80 and the partition 12s, is in a position where, looking radially outward from the axis of rotation Xc of the mating gear Gc, it partially overlaps the mating gear Gc. Since this arrangement prevents the vent chamber 60 from protruding significantly towards an axially outer side with respect to the mating gear Gc, it is also advantageous for making the gearbox housing Ct (and thus the unit housing C) more axially compact.

[0073] As from the Fig. 8 and Fig. As can be seen in Figure 9, the inlet 60i of the vent chamber 60 is located at a relatively close distance to the stator 24, which is fixed to the motor housing Cm. As described above, by arranging the inlet 60i of the vent chamber 60 adjacent to and facing the stator 24, which does not rotate within the motor chamber 20, it is possible to prevent oil from entering the vent chamber 60 through the motor chamber 20 more effectively using the stator 24.

[0074] Next, an operation in this embodiment is described. In the power unit PU, which comprises the transmission device T according to the present invention, the rotary drive force is applied from the motor output shaft 26 to the input gear Gi in accordance with the operation of the motor M. In two stages, the rotary drive force is reduced by the reduction device R within the transmission device T and transmitted to the final output gear Gf. The differential device D distributes the rotary drive force of the final output gear Gf to the first and second drive shafts 51, 52, while enabling differential rotation, and the rotary drive force is further transmitted from the first and second drive shafts 51, 52 to the left and right drive gears.

[0075] In the stopped state of the engine M, a certain amount of oil is stored in the oil reservoir 15, which is located in the lower part inside the gearbox housing Ct, and some of the oil which, in accordance with the previous operation of the engine M, has been scattered within the gearbox mechanism chamber 10 and has flowed downwards, is also stored in the auxiliary oil reservoir 71 in the input gear cover 70.

[0076] Furthermore, during a transmission of the gear mechanism G, in particular during the forward rotation of the motor M (when a vehicle begins to move forward), the input gear Gi, the mating gear Gc, the counter pinion Gcp and the final output gear Gf rotate in a direction which can be seen, for example, in the hollow arrows in the Fig. 2 and Fig. 4 is indicated. In accordance with this rotation, the oil within the oil reservoir 15 is drawn up by the final output gear Gf, which is in the lowest position and has the largest diameter, and then disperses to various parts within the gear mechanism chamber 10.

[0077] The gearbox housing Ct in this embodiment comprises the first oil collection element H1, which is capable of collecting the oil from the high-speed rotating input gear Gi. As also shown in Fig. As can be seen in Figure 4, the oil inlet opening H1i of the first oil collection element H1 is located on the front side in the forward direction of rotation of the input gear Gi, on the common tangent of the pitch circles of the input gear Gi and the mating gear Gc. This allows the first oil collection element H1 to efficiently collect the oil that splashes upwards from the input gear Gi during rotation of the input gear Gi at high speeds, after the input gear Gi and the mating gear Gc mesh, and to supply the collected oil to various lubrication target parts located within the unit housing C.

[0078] This means that the portion of the oil collected by the first oil collection part H1 is supplied to the first engine bearing Bm1 on the left side (i.e., closer to the transmission assembly T) through the first oil supply channel 17, which penetrates the partition 12s on a right side of the first oil collection part H1. A portion of the other oil, i.e., the oil that differs from that collected by the first oil collection part H1, is supplied to the second differential bearing Bf2 on the right side or to an area surrounding the second drive shaft 52 through the slotted third oil supply channel 85, which is provided on the housing body 81 of the intermediate housing 80. Furthermore, the remaining oil of the other oil described above (i.e.,the oil, which is currently flowing around the inlets of the first and third oil supply channels 17, 85) enters the through-hole 12sh, which is open to the innermost section of the first oil collection part H1, and is then supplied to the second engine bearing Bm2 on the right side (i.e. far away from the transmission device T) through the second oil supply channel 90.

[0079] As described above, the oil collected by the first oil collection part H1 efficiently lubricates the lubrication target parts inside and outside the gearbox housing Ct, i.e., each of the bearings Bm1, Bm2, Bf2 and others described above.

[0080] Furthermore, in this embodiment, the gearbox housing Ct includes the input gear cover 70, which covers the input gear Gi and is capable of storing oil in the lower section of its inner space. The first oil collection element H1 is arranged within the input gear cover 70. Accordingly, within the input gear cover 70, which includes the auxiliary oil reservoir 71 for the input gear at its inner base, it is possible to sufficiently disperse the oil from the input gear Gi by centrifugal force and to effectively collect the dispersed oil through the first oil collection element H1, which faces the oil inlet opening H1i within the input gear cover 70. This ensures the effective lubrication of the lubrication target parts described above.

[0081] The second differential bearing Bf2 on the right side in this embodiment is attached to the intermediate housing 80, which is coupled to the partition 12s of the gearbox housing Ct, and the partition 12s, together with the intermediate housing 80, defines the first oil collection element H1. That is, since the intermediate housing 80, which is a section of the molded wall of the first oil collection element H1, is also used as a bearing element for the second differential bearing Bf2, the device structure is simplified accordingly, thus achieving a cost reduction.

[0082] Furthermore, since the intermediate housing 80 includes the through-hole, i.e., the slot-like third oil supply channel 85, which directs the portion of the oil collected by the first oil catchment H1 to the second differential bearing Bf2, the oil collected by the first oil catchment H1 can be effectively used to lubricate the second differential bearing Bf2 and the like. Because it is possible to form an oil supply channel from the first oil catchment H1 to the second differential bearing Bf2 simply by providing the through-hole-like third oil supply channel 85 in the intermediate housing 80, the oil channel structure is simplified.

[0083] In the power unit PU of the embodiment, the unit housing C comprises, on its front side in the forward direction of rotation of the counter gear Gc relative to the first oil collection element H1, the second oil collection element H2, which is capable of collecting the oil scattered by the counter gear Gc. The second oil collection element H2 communicates with the first oil supply channel 90 in the second housing half 12.

[0084] Accordingly, it is possible to collect not only the oil scattered by the input gear Gi, but also the oil radially outwardly scattered by centrifugal force from the counter gear Gc, using the second oil collection element H2, and then combine the collected oils with the oil in the first oil supply channel 90 from the first oil collection element H1 towards the second motor bearing Bm2. Therefore, it is possible to lubricate the second motor bearing Bm2, which is located further away from the transmission device T, more efficiently using not only the first oil collection element H1, but also the second oil collection element H2.

[0085] In this case, if the orientation of the helical teeth of the mating gear Gc is such that the oil scatters while being biased to the axially right side relative to the gear teeth, particularly during the forward rotation of the motor M, it is possible to collect the scattered oil from the mating gear Gc more efficiently by the second oil collecting part H2, which is located axially right on a front upper outer circumference of the mating gear Gc.

[0086] In this embodiment, the final output gear Gf, being the large-diameter gear, meshes with the mating pinion Gcp in a specific semi-circular area (a semi-circular area behind the axis of rotation Xi). Fig. 2), in which the tooth surface moves from the lower end of the final output gear Gf towards its upper end in accordance with the forward rotation of the final output gear Gf. Both the mating pinion Gcp and the final output gear Gf, which is a helical gear, are arranged such that the oil at the tooth surface of the mutual engagement section 40, during the forward rotation of the final output gear Gf, flows to an axially left side of the mating pinion Gcp (i.e., into the area indicated by the dashed arrow in Fig. 1 (in the specified direction) is pressed. Furthermore, as shown, it includes... Fig. As can be seen in Figure 1, the first counter bearing Bc1 is a shielded bearing acting as a fluid boundary wall, which prevents the oil from flowing to the left side in the opposite direction to the oil being forced to the axially left side by the engagement section 40. The first counter bearing Bc1 is arranged adjacent to the axially left tooth end of the mating pinion Gcp and is shaped such that the tooth tip sections of the end faces can be covered.

[0087] Accordingly, during the forward rotation of the final output gear Gf, the oil forced from the engagement section 40 of the final output gear Gf and the counter pinion Gcp towards the axially left side of the counter pinion Gcp is prevented from flowing to the axially left side by the first counter bearing Bc1 (a shielded bearing acting as the fluid boundary wall), which opposes the forced oil flow. This allows the oil that accumulates at a point just upstream of bearing Bc1 to flow more easily to a tooth section of the final output gear Gf. This makes it easier to transport and scoop up this oil through the final output gear Gf, effectively increasing the amount of oil that the gear Gf scoops up to its upper tooth section.As a result, although such a design allows the final output gear Gf to mesh with the counter pinion Gcp while the oil is scooped up, it is possible to supply the oil sufficiently to the upper section of the final output gear Gf.

[0088] As from Fig. As can be seen in Figure 1, the axial width of the counter pinion Gcp is defined in the embodiment such that the tooth section of the pinion Gcp extends to the axially left side relative to the engagement section 40 described above. Accordingly, if the oil pressed to the axially left side by the engagement section 40 described above accumulates on a near side of the first counter bearing Bc1, which serves as the fluid boundary wall (in particular on the tooth surface extending to the axially left side relative to the engagement section 40 of the counter pinion Gcp), it is possible to scatter a portion of the accumulated oil radially outwards from the counter pinion Gcp by centrifugal force in order to supply the oil to the surrounding lubrication target parts.

[0089] In this case, since the side wall 11s of the first housing half-body 11 (in particular the bowl-shaped section which surrounds the differential housing Dc) has a plurality of oil guide ribs (not shown) on its inner circumference in a projecting manner, the oil which is scattered by the counter-pinion Gcp and which adheres to an inner surface of the side wall 11s can also be efficiently guided and supplied to the first differential bearing Bf1 on the left side.

[0090] In this embodiment, the fluid containment wall, which restricts the flow of oil forced from the engagement section 40 described above to the axially left side to accumulate at the near side, is formed by the first counter bearing Bc1, which is the shielded bearing that supports the counter pinion Gcp on the gearbox housing Ct. Accordingly, the shielded bearing utilizes a commonly employed oil sealing function, thus enabling the fluid containment wall described above to be structured simply and at low cost.

[0091] Unlike the present embodiment, in which the shielded bearing (first counter bearing Bc1) also acts as the fluid boundary wall, a variety of variations can be used as the fluid boundary wall described above. For example, a modified example is also possible in which a flat disk is held between the toothed section of the counter pinion Gcp and the first counter bearing Bc1, which is not a shielded bearing, and this flat disk is used as the fluid boundary wall. Alternatively, another modified example is also possible in which an annular, flange-like projecting wall, which is integrally formed with an outer circumferential section of the counter shaft 14 and inserted between the toothed section of the counter pinion Gcp and the first counter bearing Bc1, which is not a shielded bearing, can be used as the fluid boundary wall.

[0092] Alternatively, another modified example is possible in which a radially flat bearing (e.g., a needle bearing) is used as the first counter bearing Bc1, this radially flat bearing being located in a mating section between the counter shaft 14 and the side wall 11s of the first housing half-body 11. In this modified example, the side wall 11s has its inner wall located closer to or adjacent to a left end face of the tooth section of the counter pinion Gcp, and the inner wall of the side wall 11s can be used as the fluid boundary wall.

[0093] As from Fig.As can be seen in Figure 1, the differential housing Dc of the differential device D in this embodiment comprises the window section Dch, which is arranged in a position offset to the axially left side relative to the final output gear Gf and which allows communication between the interior and exterior of the differential housing Dc. Accordingly, when the oil described above, which is pressed onto the toothed surface of the counter pinion Gcp during the forward rotation of the final output gear Gf to the axially left side, is dispersed by centrifugal force, the oil is easily introduced into the window sections Dch. Consequently, since the oil dispersed by the counter pinion Gcp is efficiently supplied to the differential gear mechanism Dg within the differential housing Dc through the window sections Dch, the lubrication effect on the differential gear mechanism Dg can also be enhanced.

[0094] The unit housing C in this embodiment, in particular the second housing half 12, comprises the partition 12s, the left surface 12si of which faces the transmission mechanism chamber 10 and the right surface 12so faces the engine compartment 20. The left surface 12si of the partition 12s and the intermediate housing 80, which serves as a cover and is coupled to the left surface 12si, define the vent chamber 60. The inlet 60i of the vent chamber 60 is open to the right surface 12so of the partition 12s and can communicate with the engine compartment 20.

[0095] Accordingly, since the inlet 60i of the vent chamber 60 has a communicating configuration that is not directly open to the transmission mechanism chamber 10 and communicates with the transmission mechanism chamber 10 via the engine compartment 20, it is effectively prevented that the oil scattered by each gear of the gear mechanism G within the transmission housing Ct enters the vent chamber 60. This can reduce the risk of oil splashing out of the vent chamber 60.Furthermore, since the vent chamber 60 is defined by the left surface 12si of the partition 12s of the gearbox housing Ct and the intermediate housing 80, which serves as the coupled cover, it is also possible to easily obtain a hollow structure of the vent chamber 60, which is separated from the gearbox mechanism chamber 10, without complicating the structure of the partition 12s of the gearbox housing Ct and its forming process, thereby achieving a corresponding cost reduction.

[0096] Although the embodiment of the present invention has been described above, the present invention is not limited to this embodiment, and various design modifications can be made to it without deviating from the core of the present invention.

[0097] For example, in the embodiment described above, the gear mechanism G of the transmission device T comprises a so-called two-axis gear mechanism in which the input gear Gi and the final output gear Gf (and thus the drive shafts 51, 52), which rotate about an axis different from the axis Xc of the mating gear Gc, are arranged on a coaxial line. However, in the present invention, a so-called three-axis gear mechanism can be used in which the input gear Gi, the mating gear Gc, and the final output gear Gf (and thus the drive shafts 51, 52) rotate about three different axes.

[0098] In the embodiment described above, the transmission device T comprises, in addition to the reduction device R, the differential device D, in which an output from the reduction device R, i.e., a torque from the final output gear Gf, is distributed via the differential device D to the pair of drive shafts 51, 52 (and thus to the left and right drive wheels). However, in the present invention, the differential device D can be omitted, and the final output gear Gf can be locked and coupled to a single drive shaft via a locking mechanism without a differential function. In this case, the drive shaft can rotate to drive a single drive wheel (for example, a rear wheel of a motorcycle).

[0099] In the embodiment described above, power unit PU is used in a power unit for an automobile. However, the power unit of the present invention can be applied to a power unit in other machine devices besides automobiles.

[0100] In the embodiment described above, during the forward rotation of the final output gear Gf, the mating pinion Gcp and the final output gear Gf are oriented such that the orientation of the helical shapes of the helical teeth of both gears Gcp, Gf (in other words, helix angle) is fixed such that the oil on the tooth surface Gcp is forced from the engagement section 40 to the axially left side of the mating pinion in accordance with the mutual engagement between the mating pinion Gcp and the final output gear Gf. However, in the present invention, the orientation of the helical shapes of the helical teeth of both gears Gcp, Gf can be fixed in an orientation opposite to that in the embodiment described above.In this case, since the oil on the tooth surface is forced from the engagement section 40 to the axially right side of the counter pinion Gcp in accordance with the mutual engagement between the counter pinion Gcp and the final output gear Gf during the forward rotation described above, the fluid boundary wall next to the tooth end surface on the axially right side of the counter pinion Gcp is provided in a projecting ring-shaped manner on an outer circumference of the counter shaft 14 and the axial width of the counter pinion Gcp is determined such that the tooth section of the counter pinion Gcp extends from the engagement section 40 described above to the axially right side.In this setting, an extension section of the tooth section of the counter pinion Gcp is in a position that coincides axially with or is close to the second differential bearing Bf2, so that it is also possible to increase the oil supply quantity to the second differential bearing Bf2, since the oil which is forced through the extension section of the tooth section and which accumulates on the near side of the fluid boundary wall is dispersed by centrifugal force.

[0101] In the embodiment described above, the intermediate housing 80 also acts as a means of forming the vent chamber 60 together with the partition 12s, as a means of forming the input gear cover 70, and as a means of supporting the second differential bearing Bf2. However, the intermediate housing 80 can also act as any two of these means, or it can be used exclusively as any one of these means.

[0102] In the embodiment described above, each gear Gi, Gc, Gcp, Gf of the gear mechanism G of the transmission device T is formed from a helical gear. However, at least one gear pair of these gears Gi, Gc, Gcp, Gf (for example, a gear pair consisting of the input gear Gi and the mating gear Gc, or a gear pair consisting of the final output gear Gf and the mating pinion Gcp), which mesh with each other, can each be formed from a spur gear. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] JP 2017-161000

[0003]

Claims

[1] Breather structure in a power unit (PU), wherein the power unit (PU) comprises: an engine (M); and a transmission device (T) adapted to receive an output of the engine (M), the transmission device (T) comprising: a gear transmission mechanism (G) capable of transmitting the output of the motor (M) to a drive shaft (51, 52); and a gear housing (Ct) comprising therein a gear mechanism chamber (10) which accommodates the gear transmission mechanism (G), the gear housing (Ct) and a motor housing (Cm) for the motor (M) forming a unit housing (C) of the power unit, wherein the unit housing (C) comprises: an oil supply channel (17, 90) which is arranged to supply at least one bearing (Bm1, Bm2) of an engine output shaft (26) with a part of an oil lubricating the gear transmission mechanism (G); an oil return passage (16) adapted to return oil from an engine compartment (20) within the engine housing (Cm) to the transmission mechanism chamber (10); and a partition wall (12s) in which one side surface (12si) faces the gear mechanism chamber (10) and another side surface (12so) faces the engine compartment (20), wherein the one side surface (12si) of the partition wall (12s) and a cover (80) coupled to the one side surface (12si) define a vent chamber (60) which is shielded from the gear mechanism chamber (10) and which is open to atmospheric air, and wherein the breather chamber (60) comprises an inlet (60i) which is open towards the other side surface (12so) of the partition wall (12s) and which communicates with the engine compartment (20). [2] Breather structure in a power unit according to claim 1, wherein the gear transmission mechanism (G) comprises, on an output side of a gear transmission path thereof, a final driven gear (Gf) which is adapted to transmit a rotational drive force to the drive shaft (51, 52), and wherein, viewed from an axial direction of the final driven gear (Gf), at least a portion of the breather chamber (60) overlaps with the final driven gear (Gf). [3] Breather structure in a power unit according to claim 1 or 2, wherein the gear transmission mechanism (G) comprises a counter gear (Gc) on the gear transmission path and wherein at least a portion of the vent chamber (60) overlaps with the counter gear (Gc) radially outwardly from an axis of rotation (Xc) of the counter gear (Gc). [4] A breather structure in a power unit according to any one of claims 1 to 3, wherein the other side surface (12so) of the partition wall (12s) is provided with a projecting wall (12t) which projects toward the engine compartment (20) and surrounds the inlet (60i) of the breather chamber (60). [5] Breather structure in a power unit according to one of claims 1 to 4, wherein the inlet (60i) of the breather chamber (60) faces a stator (24) which is fixed within the motor housing (Cm).

Images