Electric axle apparatus for vehicle

Abstract

The present invention secures fastening strength and bending strength.　An electric axle apparatus 100 for a vehicle comprises: an electric motor 3; a reduction gear 2 connected to an output side of the electric motor; a differential device 5 connected to an output side of the reduction gear; left and right axle shafts 21 connected to an output side of the differential device; left and right axle shaft casings 30 storing the left and right axle shafts, respectively; a common casing 31 common to the reduction gear and the differential device, the common casing being disposed between the left and right axle shaft casings and fixed to the left and right axle shaft casings with bolts 32; and a reinforcement member 33 disposed outside the common casing and connecting the left and right axle shaft casings.

Description

Electric axle device for vehicles

[0001] The present disclosure relates to an electric axle device for a vehicle.

[0002] In rigid axle suspension systems used in trucks and other vehicles, an axle housing containing a differential is connected to the vehicle body via springs such as leaf springs. In recent years, there have been examples of this axle housing being fitted with a reduction gear and an electric motor to create an electric axle device for a vehicle. Using this electric axle device for a vehicle makes it relatively easy to electrify existing vehicles.

[0003] JP 2017-150658 A

[0004] However, if a typical banjo type axle housing is used, there are problems such as restrictions on gear ratio design.

[0005] Therefore, from the perspective of ensuring design freedom, it is being considered to divide this general axle housing into a central portion that houses the differential device and left and right portions that house the left and right axle shafts, and to fasten and fix a casing common to the reducer and differential device to the left and right portions with bolts.

[0006] However, with this structure, there are problems in ensuring the fastening strength between the casing and the left and right portions, and the bending strength of the casing and the left and right portions as a whole.

[0007] The present disclosure has been made in view of the above circumstances, and its purpose is to provide an electric axle device for a vehicle that can ensure fastening strength and bending strength.

[0008] According to one aspect of the present disclosure, there is provided an electric axle device for a vehicle comprising: an electric motor; a reducer connected to the output side of the electric motor; a differential device connected to the output side of the reducer; left and right axle shafts connected to the output side of the differential device; left and right axle shaft casings that respectively accommodate the left and right axle shafts; a common casing common to the reducer and the differential device, the common casing being sandwiched between the left and right axle shaft casings and fixed to the left and right axle shaft casings with bolts; and a reinforcing member located on the outside of the common casing and connecting the left and right axle shaft casings.

[0009] Preferably, brackets are fixed to the left and right axle shaft casings by welding, and both ends of the reinforcing member are fixed to the left and right brackets by welding.

[0010] Preferably, the reinforcing member is formed of a narrow, hat-shaped metal plate extending in the left-right direction.

[0011] Preferably, the reinforcing member is disposed below the common casing.

[0012] Preferably, the reinforcing member is disposed on the upper side of the common casing.

[0013] Preferably, the reinforcing member is disposed on the rear side of the common casing.

[0014] Preferably, the common casing extends forward from a position between the left and right axle shaft casings.

[0015] Preferably, the common casing is a casting made of aluminum or an aluminum alloy.

[0016] Preferably, the left and right axle shaft casings have flanges attached to the common casing by the bolts.

[0017] Preferably, both ends of the reinforcing member are fixed to the left and right flanges.

[0018] Preferably, the reinforcing member has a main body portion extending in the left-right direction and formed with an arc-shaped cross section, and hook portions extending radially inward from the left and right ends of the main body portion, and the flange has a disk-shaped main body portion and a protrusion portion provided on the outer periphery of the main body portion and protruding radially outward, the main body portion being superimposed on the arc-shaped outer peripheral surface of the protrusion portion, and the hook portion being superimposed on the outer left-right side surface of the protrusion portion.

[0019] Preferably, the hook portion is fixed to a side surface of the protrusion on an outer side in the left-right direction by a bolt.

[0020] According to the present disclosure, fastening strength and bending strength can be ensured.

[0021] 1. A rear view of the electric axle device according to the first embodiment of the present disclosure. 2. A plan view of the electric axle device according to the first embodiment of the present disclosure. 3. A right side view of the electric axle device according to the first embodiment of the present disclosure. 4. A skeleton diagram showing a schematic internal structure of the electric axle device. 5. A cross-sectional view taken along V-V in FIG. 1. 6. A cross-sectional view taken along VI-VI in FIG. 1. 7. A rear view of the electric axle device according to the second embodiment of the present disclosure. 8. A plan view of the electric axle device according to the second embodiment of the present disclosure. 9. A right side view of the electric axle device according to the second embodiment of the present disclosure. 10. A cross-sectional view taken along X-X in FIG. 7. 11. A cross-sectional view taken along XI-XI in FIG. 9.

[0022] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. Note that the present disclosure is not limited to the following embodiments.

[0023] [First embodiment] Figures 1 to 3 show an electric axle device according to a first embodiment of the present disclosure, with Figure 1 being a rear view, Figure 2 being a plan view, and Figure 3 being a right side view. Figure 4 is a skeleton diagram that schematically shows the internal structure of the electric axle device. For convenience, the front-rear, left-right, top-bottom directions are defined as shown in the figure. These directions generally correspond to the directions of the vehicle.

[0024] The electric axle device 100 is applied to a vehicle, and in this embodiment, is configured to be applied to a truck. However, the type of vehicle is arbitrary. The electric axle device 100 is configured to drive the left and right rear wheels of the vehicle, and forms part of a rigid axle (or axle suspension) suspension system for the rear wheels.

[0025] The electric axle device 100 comprises an electric motor (motor) 3, a reducer 2 connected to the output side of the electric motor 3, a differential device 5 connected to the output side of the reducer 2, left and right axle shafts 21 (21L, 21R, see Figure 4) connected to the output side of the differential device 5, and left and right axle shaft casings 30 (30L, 30R) that respectively accommodate the left and right axle shafts 21.

[0026] The electric axle device 100 also includes a common casing 31 that is common to the reducer 2 and the differential device 5. The common casing 31 is an integrated unit consisting of the casing of the reducer 2 and the casing of the differential device 5. The common casing 31 is sandwiched between the left and right axle shaft casings 30, and is fixed to the left and right axle shaft casings 30 with a plurality of bolts 32. Note that in the figure, only the center lines of the bolts 32 are shown by virtual lines (the same applies hereinafter).

[0027] The left and right axle shaft casings 30 form the left and right portions of a typical axle housing, and the common casing 31 forms the center portion of the typical axle housing.

[0028] The common casing 31 extends forward from a position between the left and right axle shaft casings 30. The common casing 31 is a casting made of aluminum or an aluminum alloy. On the other hand, the left and right axle shaft casings 30 are made of iron and are constructed by assembling multiple parts through welding.

[0029] In this embodiment, the common casing 31 is not shared with the electric motor 3. The casing 29 of the electric motor 3 is fixed to the common casing 31 by a plurality of bolts 35 (see FIG. 4 ). The electric motor 3 includes electrical components (not shown) such as a stator and a rotor housed in the casing 29.

[0030] 4, the reducer 2 includes a gear mechanism 6 housed in a common casing 31. The gear mechanism 6 of this embodiment is configured to reduce the rotational driving force of the electric motor 3 in three stages and transmit the reduced speed to the differential device 5.

[0031] The gear mechanism 6 includes a drive shaft 10 coaxially connected to the output shaft 9 of the electric motor 3, a first reduction shaft 11A and a second reduction shaft 11B provided parallel to the drive shaft 10, and a drive pinion gear 12 and a first spur gear 13A attached to the drive shaft 10 and the first reduction shaft 11A, respectively, and meshed with each other. The number of teeth of the first spur gear 13A is greater than the number of teeth of the drive pinion gear 12.

[0032] The gear mechanism 6 also includes a first pinion gear 13B and a second spur gear 14A attached to the first reduction shaft 11A and the second reduction shaft 11B, respectively, and meshing with each other, and a second pinion gear 14B attached to the second reduction shaft 11B. The number of teeth of the second spur gear 14A is greater than the number of teeth of the first pinion gear 13B.

[0033] The gear mechanism 6 also includes a plurality of bearings 15 fixed to the common casing 31 and rotatably supporting the drive shaft 10, the first reduction shaft 11A, and the second reduction shaft 11B, respectively.

[0034] The differential device 5 includes a differential mechanism 1 housed in a common casing 31. The differential mechanism 1 includes a differential case 16, a plurality of bearings 17 fixed to the common casing 31 and rotatably supporting the differential case 16, and a differential spur gear 18 fixed to the differential case 16 and meshed with the second pinion gear 14B. The number of teeth of the differential spur gear 18 is greater than the number of teeth of the second pinion gear 14B.

[0035] The differential mechanism 1 also includes a plurality of differential pinion gears 19 rotatably supported within the differential case 16, and left and right side gears 20 (20L, 20R) rotatably supported within the differential case 16 and meshed with the plurality of differential pinion gears 19. Left and right axle shafts 21 are coaxially connected to the left and right side gears 20, respectively.

[0036] The second pinion gear 14B and the differential spur gear 18 are parallel-axis gears (spur gears, helical gears, etc.). This simplifies manufacturing and improves vibration and noise performance compared to intersecting-axis gears (bevel gears, etc.). The other gears 12, 13A, 13B, and 14A are also parallel-axis gears.

[0037] Alternatively, at least one of the gear sets may comprise intersecting axis gears.

[0038] The center of the output shaft 9 of the electric motor 3 is defined as the electric motor center C1. The center of the drive shaft 10 of the reducer 2 is defined as the reducer center C2. The center of the axle shaft 21 is defined as the axle shaft center C3. The electric motor center C1 and the reducer center C2 are coaxial, and the electric motor center C1, the reducer center C2, and the axle shaft center C3 are parallel to one another. The electric motor center C1, the reducer center C2, and the axle shaft center C3 extend in the left-right direction. The electric motor center C1 and the reducer center C2 are located forward of the axle shaft center C3.

[0039] The reduction gear 2 is disposed in front of the differential device 5, and the electric motor 3 is disposed in front of the differential device 5 and to the side (left side) of the reduction gear 2. This allows the entire electric axle device 100 to be made compact.

[0040] 1 and 2, the common casing 31 is divided into two split casings 34L, 34R, left and right. After the joints (joint surfaces) 35L, 35R of the split casings 34L, 34R, which are perpendicular to the axle shaft center C3, are joined together, the split casings 34L, 34R are fixed to each other with a plurality of bolts 36. The joint position of the joints 35L, 35R is defined as a reference position C4 in the left-right direction.

[0041] In the left-right direction, the direction approaching the reference position C4 is the inside in the left-right direction or the inside in the vehicle width direction, and the direction away from the reference position C4 is the outside in the left-right direction or the outside in the vehicle width direction.

[0042] The left and right axle shaft casings 30 are configured to be generally symmetrical with respect to the left and right, although their lengths in the left-right direction are slightly different.

[0043] The axle shaft casing 30 is formed in a cylindrical shape that extends in the left-right direction. A hub flange 24 for connecting an axle hub (not shown) and a spring bracket 25 for seating a suspension spring such as a leaf spring are integrally fixed by welding to the longitudinal middle portion of the axle shaft casing 30. The spring bracket 25 is positioned inward in the vehicle width direction from the hub flange 24.

[0044] The axle shaft casing 30 has a cylindrical shape with a circular cross section at the attachment portion of the hub flange 24 and at the portion on the vehicle width outer side thereof. The axle shaft casing 30 has a rectangular cross section with rounded corners and a constant front-to-rear width, as shown in Figures 5 and 6 , at the portion on the vehicle width inner side of the attachment portion of the hub flange 24.

[0045] As shown in FIG. 1, the portion of the axle shaft casing 30 that is located inward in the vehicle width direction from the spring bracket 25 has a height (vertical) dimension that gradually increases as it moves inward in the vehicle width direction.

[0046] The spring brackets 25 are attached symmetrically to the upper and lower surfaces of the axle shaft casing 30. The spring brackets 25 are formed of a metal plate, specifically an iron plate, that is U-shaped when viewed from the rear as shown in Figure 1. The upper spring bracket 25 is formed in a U-shape with an open bottom, and the lower spring bracket 25 is formed in a U-shape with an open top.

[0047] The upper and lower spring brackets 25 are symmetrical from top to bottom, so only the upper spring bracket 25 will be described here. As shown in Figure 5, the upper spring bracket 25 has a greater front-to-rear width than the axle shaft casing 30. The lower end surface of the upper spring bracket 25 is formed with a recess 37 that fits into the upper surface of the axle shaft casing 30. After the recess 37 is fitted into the upper surface of the axle shaft casing 30, the upper spring bracket 25 is fixed to the axle shaft casing 30 by fillet welding.

[0048] As shown in Figures 1 to 4, the left and right axle shaft casings 30 have disk-shaped flanges 38 (38L, 38R) at their inner ends in the vehicle width direction that are attached to the common casing 31 by a plurality of bolts 32. The flanges 38 are fixed to the axle shaft casings 30 by welding. After the common casing 31 and the flanges 38 are joined together, these joints are fixed by a plurality of bolts 32. The bolts 32 are attached at equal intervals around the circumferential direction of the flanges 38.

[0049] More specifically, the left flange 38L is fixed to the left end (outer side in the vehicle width direction) of the left split casing 34L with bolts 32. The right flange 38R is fixed to the right end (outer side in the vehicle width direction) of the right split casing 34R with bolts 32.

[0050] The axle shaft casing 30 is assembled by welding together previously separated parts. That is, the axle shaft casing 30 is formed by welding together a cylindrical part 30A, which is formed by welding together the hub flange 24 and its outer portion in the vehicle width direction, two rectangular cylindrical parts 30U and 30D, which are separated into upper and lower parts and are positioned inward in the vehicle width direction from the hub flange 24, and the flange 38, which are also welded together.

[0051] As shown in FIGS. 1 to 3 , the electric axle device 100 includes an inverter 39 attached to the outer periphery of the casing 29 of the electric motor 3. The inverter 39 is an electrical component for controlling the rotation of the electric motor 3 and is electrically connected to the electric motor 3 via a relatively short cable. In this embodiment, the inverter 39 is formed in the shape of a flat rectangular box, placed horizontally on the upper surface of the casing 29, and fixed to the casing 29 with bolts (not shown). This allows the weight of the inverter 39 to be supported from below by the casing 29. The inverter 39 is disposed to the left of a reference position C4 in the left-right direction.

[0052] The electric axle device 100 also includes a parking lock actuator 40 attached to the outer periphery of the common casing 31. When activated, the parking lock actuator 40 meshes with a gear (e.g., the drive pinion gear 12) of the gear mechanism 6 to lock the gear, thereby realizing an electric parking brake. The parking lock actuator 40 is formed in the shape of a flat rectangular box that is smaller than the inverter 39, and is placed horizontally on the upper surface of the common casing 31 and fixed to the common casing 31 with bolts (not shown). This allows the weight of the parking lock actuator 40 to be supported from below by the common casing 31.

[0053] The park lock actuator 40 is disposed to the right of the inverter 39, straddling the reference position C4 in the left-right direction, and above the front end of the common casing 31. Therefore, the park lock actuator 40 is disposed across the left and right split casings 34L, 34R.

[0054] The inverter 39 and the parking lock actuator 40 are both disposed rearward of the front end of the common casing 31 and are disposed so as not to protrude forward from the common casing 31. This allows the electric axle device 100 to be made compact.

[0055] In this embodiment, in order to ensure design freedom, the casings of the reducer 2 and the differential device 5 are integrated into a common casing 31, and the left and right axle shaft casings 30 are fastened and fixed to this common casing 31 with bolts 32.

[0056] However, with this structure, there are problems in ensuring the fastening strength between the common casing 31 and the left and right axle shaft casings 30, and the bending strength of the common casing 31 and the left and right axle shaft casings 30 as a whole.

[0057] Therefore, in this embodiment, in order to ensure such fastening strength and bending strength, a reinforcing member 33 is provided that is disposed on the outside of the common casing 31 and connects the left and right axle shaft casings 30. This point will be described below.

[0058] 1 to 3, in this embodiment, a plurality of (specifically, three) reinforcing members 33 are provided, including a lower reinforcing member 33D disposed below the common casing 31, an upper reinforcing member 33U disposed above the common casing 31, and a rear reinforcing member 33R disposed behind the common casing 31. These members have the same configuration.

[0059] 1, 3, and 6, the reinforcing member 33 is formed from a long, narrow metal plate that extends in the left-right direction and is hat-shaped when viewed from the rear (FIG. 1). The cross section of the reinforcing member 33 is a rectangle with a thickness t smaller than a width W. The reinforcing member 33 is made of iron, and is formed by bending a long, narrow solid iron plate into a hat shape by press working or the like. The reinforcing member 33 is configured symmetrically.

[0060] The lower reinforcing member 33D is formed in a hat shape that is convex downward, the upper reinforcing member 33U is formed in a hat shape that is convex upward, and the rear reinforcing member 33R is formed in a hat shape that is convex backward, thereby avoiding the common casing 31 and preventing interference with the common casing 31.

[0061] In this embodiment, brackets 41 are fixed to the left and right axle shaft casings 30 (30L, 30R) by welding, and both ends of the reinforcing member 33 are fixed to the left and right brackets 41 by welding.

[0062] The bracket 41 has a similar structure to the spring bracket 25 described above. The bracket 41 is formed from a metal plate, specifically a steel plate, that is U-shaped when viewed from the rear. The bracket 41 integrally includes a flat plate portion 42 on which the reinforcing member 33 is seated and fixed, and a pair of legs 43 extending perpendicularly from both left and right ends of the flat plate portion 42. The bracket 41 is attached to a portion of the axle shaft casing 30 between the spring bracket 25 and the flange 38, where the height dimension gradually changes.

[0063] The width W1 of the bracket 41 is set equal to the width W of the reinforcing member 33. These widths W and W1 are slightly smaller than the front-to-rear width W2 of the axle shaft casing 30. Because the height H2 of the axle shaft casing 30 is larger than the front-to-rear width W2, the widths W and W1 of the reinforcing member 33 and the bracket 41 are smaller than the height H2 of the axle shaft casing 30. The bracket 41 and the reinforcing member 33 are fixed so that both end faces in the width W1 and W directions are in the same position.

[0064] Three brackets 41 are provided on each of the left and right axle shaft casings 30 in correspondence with the three reinforcing members 33 .

[0065] For the lower reinforcing member 33D, brackets 41 are attached to the undersides of the left and right axle shaft casings 30. The brackets 41 are arranged so as to form a U-shape with an open top. Shallow recesses 44 that match the shape of the undersides of the axle shaft casings 30 are formed in the upper end surfaces of a pair of legs 43. After the recesses 44 are fitted into the undersides of the axle shaft casings 30, the legs 43 of the brackets 41 are fillet-welded to the undersides of the axle shaft casings 30 and fixed. In the fixed state, the lower reinforcing member 33D and brackets 41 do not protrude from the axle shaft casings 30 in the front or rear.

[0066] The upper reinforcing member 33U is the same as the lower reinforcing member 33D except that it is upside down, so a description thereof will be omitted.

[0067] The rear reinforcing member 33R has the same configuration as the lower reinforcing member 33D, but with its orientation rotated 90 degrees rearward around the axle shaft center C3. However, the rear surfaces of the left and right axle shaft casings 30 each have a flat surface whose height is greater than the width W1 of the bracket 41. Therefore, the tip surfaces of the pair of legs 43 of the bracket 41 do not have the recesses 44 described above. After the flat tip surfaces of the legs 43 are seated on the flat rear surface of the axle shaft casing 30, the legs 43 are fillet-welded to the rear surface of the axle shaft casing 30 and fixed thereto. In the fixed state, the rear reinforcing member 33R and bracket 41 do not protrude vertically beyond the axle shaft casing 30.

[0068] 1 to 3, the left end surface of each reinforcing member 33 is positioned in the left-right direction so as to coincide with the left end surface of the left bracket 41. The right end surface of each reinforcing member 33 is positioned in the left-right direction so as to coincide with the right end surface of the right bracket 41.

[0069] The lower reinforcing member 33D, the upper reinforcing member 33U and the rear reinforcing member 33R are arranged at equal intervals of 90° in the circumferential direction around the axle shaft center C3.

[0070] The lower reinforcing member 33D and the upper reinforcing member 33U are arranged horizontally so that their width W direction coincides with the front-to-rear direction, thereby minimizing the projected area of ​​the lower reinforcing member 33D and the upper reinforcing member 33U when viewed from the front, and minimizing the increase in air resistance caused by them.

[0071] The rear reinforcing member 33R is also vertically disposed so that its width W coincides with the up-down direction. This maximizes the projected area of ​​the rear reinforcing member 33R when viewed from the front. However, the rear reinforcing member 33R is hidden behind the common casing 31 and is not directly exposed to the wind while the vehicle is traveling. Therefore, the rear reinforcing member 33R does not substantially increase air resistance.

[0072] In this embodiment, the common casing 31 extends forward from a position between the left and right axle shaft casings 30. Therefore, no reinforcing member 33 is provided in front of the common casing 31, but reinforcing members 33 are provided below, above, and behind the common casing 31.

[0073] In this manner, in this embodiment, the left and right axle shaft casings 30 are connected by the reinforcing member 33. This not only increases the fastening strength between the common casing 31 and the left and right axle shaft casings 30, but also increases the bending strength of the common casing 31 and the left and right axle shaft casings 30 as a whole. This makes it possible to ensure sufficient fastening strength and bending strength. Additionally, in this embodiment, the torsional strength of the common casing 31 and the left and right axle shaft casings 30 as a whole can also be increased.

[0074] In this embodiment, it is possible to further ensure fastening strength, bending strength, and torsional strength by providing multiple reinforcing members 33. Furthermore, the lower reinforcing member 33D, the upper reinforcing member 33U, and the rear reinforcing member 33R are arranged in a balanced manner in the circumferential direction around the axle shaft center C3, thereby achieving an optimal strength balance.

[0075] The reinforcing members 33 are arranged on the outside of the common casing 31 with gaps between them. There are also gaps between the three reinforcing members 33D, 33U, and 33R. This allows outside air and wind from running to directly hit the common casing 31 through these gaps. This allows the common casing 31 to be sufficiently air-cooled.

[0076] Furthermore, heat from the common casing 31 is transferred to the reinforcing member 33 through the axle shaft casing 30 and the bracket 41, and the heat from the reinforcing member 33 is dissipated into the outside air, so air cooling of the common casing 31 is also possible through the reinforcing member 33.

[0077] In this embodiment, the lower reinforcing member 33D also serves to block stones flying from the vehicle while it is in motion, thereby protecting the common casing 31 and the axle shaft casing 30. The lower reinforcing member 33D can also be used as a jack-up point during vehicle maintenance.

[0078] In this embodiment, the reinforcing member 33 is attached to the axle shaft casing 30 via the bracket 41, which makes it easy to attach the reinforcing member 33 and also allows the attachment position of the reinforcing member 33 to be adjusted using the bracket 41. Therefore, a common reinforcing member 33 can be used as the three reinforcing members 33D, 33U, and 33R, which reduces costs by standardizing parts. In fact, this is the case in this embodiment.

[0079] In this embodiment, the inverter 39 is attached to the outer periphery (particularly the top surface) of the casing 29 of the electric motor 3. Typically, the inverter is attached to the vehicle body and connected to the electric motor via a relatively long cable. However, this requires routing a relatively long cable along a predetermined route, which makes assembly difficult.

[0080] Furthermore, when the vehicle is running, the electric motor rises and falls relative to the vehicle body. Meanwhile, the inverter is fixed to the vehicle body. Therefore, the cable must constantly deform to follow the rise and fall of the electric motor relative to the inverter, which may result in damage or breakage of the cable. Furthermore, unnecessary loads are placed on the connectors connecting the cable to the inverter and electric motor, which may damage the connector connections. All of these factors lead to reduced reliability.

[0081] However, in this embodiment, the inverter 39 is attached to the outer periphery of the casing 29 of the electric motor 3. This allows the cable connecting the inverter 39 and the electric motor 3 to be shortened, facilitating cable routing and improving assembly efficiency.

[0082] Furthermore, when the electric motor 3 moves up and down relative to the vehicle body while the vehicle is running, the inverter 39 also moves up and down together with the electric motor 3. As a result, no relative movement occurs between the inverter 39 and the electric motor 3, preventing deformation of the cable when the inverter 39 and the electric motor 3 move up and down. This prevents damage or breakage of the cable due to the relative movement between the two. Furthermore, unnecessary loads are not placed on the connectors connecting the cable to the inverter 39 and the electric motor 3, preventing damage to the connector connections. This significantly improves reliability.

[0083] Second Embodiment Next, a second embodiment of the present disclosure will be described. Note that a description of the same parts as in the first embodiment will be omitted, and the following description will mainly focus on the differences from the first embodiment.

[0084] 7 to 9 show an electric axle device 200 according to a second embodiment, with FIG. 7 being a rear view, FIG. 8 being a plan view, and FIG. 9 being a right side view.

[0085] As shown in Figures 7 to 9, in this embodiment, multiple (specifically, three) reinforcing members 33 are provided, including a lower reinforcing member 33D arranged on the lower side of the common casing 31, an upper reinforcing member 33U arranged on the upper side of the common casing 31, and a rear reinforcing member 33R arranged on the rear side of the common casing 31.

[0086] In this embodiment, both ends of the reinforcing member 33 are fixed to the left and right flanges 38 (38L, 38R). Therefore, the bracket 41 in the first embodiment is omitted, which reduces the number of parts and manufacturing costs and simplifies manufacturing.

[0087] As shown in FIG. 10 , the flange 38 includes a disk-shaped main body 50 similar to that of the first embodiment, but also includes protrusions 51 extending radially outward from the outer periphery of the main body 50. Here, the radial direction refers to the radial direction relative to the axle shaft center C3. Reinforcing members 33 are attached to the protrusions 50 in a stacked manner. Three protrusions 51, namely, a lower protrusion 51D, an upper protrusion 51U, and a rear protrusion 51R, are provided corresponding to the three reinforcing members 33. The protrusions 51 have an arc-shaped outer periphery when viewed axially relative to the axle shaft center C3. The arc-shaped outer peripheries of the lower protrusion 51D, the upper protrusion 51U, and the rear protrusion 51R all have the same radius relative to the axle shaft center C3.

[0088] In the circumferential direction based on the axle shaft center C3, the phase centers of the lower protrusion 51D, the upper protrusion 51U, and the rear protrusion 51R are designated PD, PU, ​​and PR, respectively, and the phase widths are designated WD, WU, and WR, respectively. The phase centers PD, PU, ​​and PR of these protrusions 51D, 51U, and 51R are spaced approximately equally apart, spaced approximately 90° from one another. The phase centers PD and PU of the lower protrusion 51D and the upper protrusion 51U are offset clockwise in the figure by a predetermined angle θD, θU relative to the vertical axis. The phase center PR of the rear protrusion 51R is also offset clockwise in the figure by a predetermined angle θR relative to the longitudinal axis. θD, θU, and θR are approximately equal angles. As a result, when the electric axle device 200 is mounted on a vehicle in a rearward tilted state, the phase center PD of the lower protrusion 51D is positioned almost directly below the axle shaft center C3, the phase center PU of the upper protrusion 51U is positioned almost directly above, and the phase center PR of the rear protrusion 51R is positioned almost directly behind.

[0089] The phase widths WU and WR of the upper protrusion 51U and the rear protrusion 51R are approximately equal. On the other hand, the phase width WD of the lower protrusion 51D is larger than the phase widths WU and WR and is preferably at or near 90°, although this may be any value. In this embodiment, the phase width WD is 90°, with the portion forward of the vertical axis passing through the axle shaft center C3 being 25° and the portion rearward being 65°.

[0090] As shown in detail in Figures 10 and 11, the reinforcing member 33 has a main body 52 that extends in the left-right direction and has an arc-shaped cross section (see Figure 10), and hook portions 53 that extend radially inward (based on the axle shaft center C3) from the left and right ends of the main body 52. ​​The reinforcing member 33 is formed from a metal plate. Specifically, the reinforcing member 33 is made of iron, and is formed by forming a long, solid iron plate into an arc-shaped cross section by press working or the like and bending both ends at right angles to form the reinforcing member 33. The reinforcing member 33 is configured symmetrically.

[0091] Since such a reinforcing member 33 is attached by overlapping it with the protruding portion 51, it can avoid the common casing 31 and avoid interference with the common casing 31, similar to the hat-shaped reinforcing member 33 of the first embodiment.

[0092] The main body 52 of the reinforcing member 33 is overlapped with the arc-shaped outer peripheral surface of the protruding portion 51. The left and right hook portions 53 of the reinforcing member 33 are overlapped with the outer side surfaces in the left-right direction of the protruding portions 51 of the left and right flanges 38L, 38R. In other words, the reinforcing member 33 is fitted across the protruding portions 51 of the left and right flanges 38L, 38R so as to sandwich these protruding portions 51 therebetween.

[0093] A relatively shallow groove 54 for fitting the outer periphery of the protrusion 51 is formed on the rear surface (radially inner surface) of the main body 52 at a location adjacent to the hook portion 53. This allows the reinforcing member 33 to be accurately positioned in the left-right direction relative to the flange 38, and also improves the rigidity of the reinforcing member 33 after installation.

[0094] The hook portions 53 are fixed to the outer side surfaces of the protrusions 51 in the left-right direction by bolts 55. That is, bolt insertion holes 56 are formed to pass through the hook portions 53, and screw holes 57 are formed to pass through the protrusions 51. The bolts 55 are inserted into the bolt insertion holes 56 from the outer side in the left-right direction and tightened into the screw holes 57. This allows the reinforcing members 33 to be detachably fixed to the flanges 38L, 38R.

[0095] A plurality of such bolt fixing points are provided: two points for the upper reinforcing member 33U and the rear reinforcing member 33R, and four points for the lower reinforcing member 33D.

[0096] 10 , the lower reinforcing member 33D, the upper reinforcing member 33U, and the rear reinforcing member 33R have the same phase centers PD, PU, ​​PR and phase widths WD, WU, WR as the lower protrusion 51D, the upper protrusion 51U, and the rear protrusion 51R. Therefore, the phase centers PD, PU, ​​PR and phase widths WD, WU, WR of the protrusions 51D, 51U, 51R may be rephrased as the phase centers PD, PU, ​​PR and phase widths WD, WU, WR of the reinforcing members 33D, 33U, 33R.

[0097] The phase widths WU and WR of the upper reinforcing member 33U and the rear reinforcing member 33R are approximately equal. On the other hand, the phase width WD of the lower reinforcing member 33D is larger than the phase widths WU and WR and is preferably at or near 90°, although this may be any value. In this embodiment, the phase width WD is 90°, with the portion forward of the vertical axis passing through the axle shaft center C3 being 25° and the portion rearward being 65°.

[0098] By increasing the phase width WD of the lower reinforcing member 33D in this way, it is possible to block flying stones over a wider area by the lower reinforcing member 33D during travel. Furthermore, when the lower reinforcing member 33D is used as a jacking point, the load acting on the lower reinforcing member 33D can be distributed over a wider area.

[0099] In addition, the thickness tD of the main body 52 of the lower reinforcing member 33D is greater than the thicknesses tU and tR of the main body 52 of the upper reinforcing member 33U and the rear reinforcing member 33R, thereby increasing the rigidity of the lower reinforcing member 33D and making it suitable as a jack-up point.

[0100] When the vehicle is mounted, a jack is placed near the phase center PD of the lower reinforcing member 33D, but in this embodiment, there are no bolts 55 in the area near the phase center PD, which makes it possible to suppress deformation of the bolts 55 due to the load when the vehicle is jacked up.

[0101] The thicknesses tU and tR of the main body portions 52 of the upper reinforcing member 33U and the rear reinforcing member 33R are equal to each other. The upper reinforcing member 33U and the rear reinforcing member 33R may be the same component, which can reduce manufacturing costs.

[0102] The effects of this embodiment are basically the same as those of Embodiment 1. In addition, in this embodiment, the reinforcing member 33 is fixed to the flange 38, so the bracket 41 of the first embodiment can be omitted, and the reduced number of parts reduces costs and simplifies manufacturing.

[0103] Furthermore, while in the first embodiment the width W of the reinforcing members 33D, 33U, and 33R is limited to some extent by the width W1 of the bracket 41 (see FIG. 6 ), in this embodiment there is no such limitation on the phase widths WD, WU, and WR of the reinforcing members 33D, 33U, and 33R. Furthermore, the total circumferential length of the flange 38 in this embodiment is significantly greater than the total width W1 of the bracket 41 in the first embodiment. Therefore, the phase widths WD, WU, and WR of the reinforcing members 33D, 33U, and 33R in this embodiment can be made greater than the width W of the reinforcing members 33D, 33U, and 33R in the first embodiment. Therefore, in this embodiment, the fastening strength and bending strength can be increased compared to the first embodiment. In fact, the phase width WD of the lower reinforcing member 33D in this embodiment is significantly greater than the width W of the lower reinforcing member 33D in the first embodiment.

[0104] Furthermore, since the reinforcing member 33 has a main body portion 52 with an arc-shaped cross section and hook portions 53 at the left and right ends of the main body portion 52, the rigidity of the reinforcing member 33 can be increased, which is further advantageous in ensuring fastening strength and bending strength.

[0105] The flange 38 is provided with a protrusion 51, and the main body 52 of the reinforcing member 33 is overlapped on its outer peripheral surface, so that the reinforcing member 33 is spaced radially outward from the common casing 31, thereby suitably preventing interference therebetween.

[0106] The left and right hook portions 53 are overlapped with the outer side surfaces of the left and right protrusions 51 in the left-right direction, so that the reinforcing member 33 can be accurately positioned in the left and right direction relative to the left and right flanges 38.

[0107] The left and right hook portions 53 are fixed to the outer side surfaces of the left and right protrusions 51 in the left-right direction with bolts 55, so the hook portions 53 can be firmly and easily fixed. Furthermore, the reinforcing member 33 can restrain the opening and closing movement of the left and right flanges 38 when the electric axle device 200 is bent. In addition, the reinforcing member 33 is detachable and can be replaced if damaged, for example.

[0108] Although the embodiments of the present disclosure have been described in detail above, various other embodiments and modifications of the present disclosure are possible.

[0109] For example, the reinforcing member 33 may have a structure other than that described above. The reinforcing member 33 of the first embodiment may have another cross-sectional shape (e.g., a circle) or may have a hollow structure instead of a solid structure. Therefore, the reinforcing member 33 may be formed as a circular shaft, a square shaft, a circular tube, a square tube, or the like.

[0110] Similarly, the axle shaft casing 30 may have a structure other than that described above. For example, the cross-sectional shape of the portion located inward in the vehicle width direction from the hub flange 24 may be circular or elliptical. Additionally, the shapes of the seating surfaces of the spring bracket 25 and the bracket 41 may be changed accordingly.

[0111] The reinforcing member 33 of the first embodiment may be welded directly to the axle shaft casing 30 without using the bracket 41 .

[0112] The number of reinforcing members 33 can be changed, and may be one, two, or four or more. For example, only one or two of the lower reinforcing member 33D, the upper reinforcing member 33U, and the rear reinforcing member 33R may be provided.

[0113] In the first embodiment, if possible, the reinforcing member 33 may be fixed to the bracket 41 or the axle shaft casing 30 with bolts.

[0114] In the second embodiment, if possible, both left and right end portions of the reinforcing member 33 may be fixed to the left and right flanges 38L, 38R by welding.

[0115] The embodiments of the present disclosure are not limited to the above-described embodiments, and all modifications, applications, and equivalents encompassed within the spirit of the present disclosure as defined by the claims are included in the present disclosure. Therefore, the present disclosure should not be interpreted as being limited, and can be applied to any other technology that falls within the spirit of the present disclosure.

Claims

1. An electric axle device for a vehicle comprising: an electric motor; a reduction gear connected to an output side of the electric motor; a differential device connected to an output side of the reduction gear; left and right axle shafts connected to the output side of the differential device; left and right axle shaft casings which respectively house the left and right axle shafts; a common casing common to the reduction gear and the differential device, the common casing being sandwiched between the left and right axle shaft casings and fixed to the left and right axle shaft casings with bolts; and a reinforcing member located on the outside of the common casing and connecting the left and right axle shaft casings.

2. The vehicle electric axle device according to claim 1, wherein brackets are fixed to the left and right axle shaft casings by welding, and both ends of the reinforcing member are fixed to the left and right brackets by welding.

3. The vehicle electric axle device according to claim 1, wherein the reinforcing member is formed of a long, narrow metal plate extending in the left-right direction and formed into a hat shape.

4. The vehicle electric axle device according to claim 1, wherein the reinforcing member is disposed below the common casing.

5. The vehicle electric axle device according to claim 1, wherein the reinforcing member is disposed on the upper side of the common casing.

6. The vehicle electric axle device according to claim 1, wherein the reinforcing member is disposed on the rear side of the common casing.

7. The vehicle electric axle device according to claim 1, wherein the common casing extends forward from a position between the left and right axle shaft casings.

8. The vehicle electric axle device according to claim 1, wherein the common casing is a casting made of aluminum or an aluminum alloy.

9. The vehicle electric axle device according to claim 1, wherein the left and right axle shaft casings have flanges that are attached to the common casing by the bolts.

10. The vehicle electric axle device according to claim 9, wherein both ends of the reinforcing member are fixed to the left and right flanges.

11. The electric axle device for a vehicle as described in claim 10, wherein the reinforcing member has a main body portion extending in the left-right direction and formed with an arc-shaped cross section, and hook portions extending radially inward from the left and right ends of the main body portion, and the flange has a disk-shaped main body portion and a protrusion portion provided on the outer periphery of the main body portion and protruding radially outward, the main body portion being superimposed on the arc-shaped outer periphery of the protrusion portion, and the hook portion being superimposed on the outer left-right side surface of the protrusion portion.

12. The vehicle electric axle device according to claim 11, wherein the hook portion is fixed to the outer side surface of the protrusion in the left-right direction by a bolt.

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