Transmission member

Abstract

To provide a transmission member in which a drive device of an electric vehicle including a differential gear can be effectively used in another power generation system, and a diverting method of the drive device of the electric vehicle.SOLUTION: The present invention is a transmission member that is accommodated in the housing instead of a differential gear and transmits power from a drive source of a power generation system in a drive device of an electric vehicle at least including a rotary electric machine, a decelerator, and a housing accommodating the differential gear. The transmission member includes: a shaft member connectable with the drive source, a support part fixed to the shaft member and radially extending from the shaft member, and a gear that is fixed to the support part and transmits power to the decelerator.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a transmission member, a component of a power generation system, and a method for converting a drive unit of an electric vehicle. [Background technology]

[0002] Patent Document 1 describes a technique for reusing a drive unit of a vehicle, including an electric vehicle, in a wind power generation system. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-140743 Summary of the Invention [Problem to be solved by the invention]

[0004] In particular, since electric vehicles include a motor, it is effective to apply a drive unit including this motor to a power generation system. However, although Patent Document 1 describes in detail the repurposing of a traveling drive shaft included in the drive unit of an automobile, it does not provide detailed descriptions of how other parts can be repurposed.

[0005] Electric vehicle drivetrains generally include a differential, but wind and hydroelectric power plants use a single turbine shaft to generate electricity, so if the drivetrain includes a differential, one of the two driveshafts must be locked (differentially locked) so that it cannot be used.However, if such a differential lock is not in place, the gear not connected to the turbine shaft will continue to spin freely, resulting in a loss of generated energy.

[0006] As described above, automobile drivetrains are equipped with differentials for transmitting power to the left and right wheels, but no appropriate methods for handling and utilizing the differentials have been proposed, which has led to the problem of not being able to effectively utilize the drivetrain.

[0007] The present invention has been made to solve the above-mentioned problems, and aims to provide a transmission member that allows an electric vehicle drive unit, including a differential gear, to be effectively converted into another power generation system, and a method for converting an electric vehicle drive unit using the same. [Means for solving the problem]

[0008] The present invention relates to a drive unit for an electric vehicle, which includes a housing that houses at least a transmission and a differential gear. The drive unit is a transmission member that is housed in the housing in place of the differential gear and transmits power from a drive source of a power generation system, and includes a shaft member that can be connected to the drive source, a support portion that is fixed to the shaft member and extends radially from the shaft member, and a gear that is fixed to the support portion and transmits power to the transmission. [Effects of the Invention]

[0009] According to the present invention, a drive unit of an electric vehicle including a differential gear can be effectively used for other power generation systems. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a cross-sectional view showing an embodiment of a drive device before a transmission member according to the present invention is attached. [Figure 2] FIG. 2 is a perspective view of the transmission member as seen from the right side. [Figure 3] FIG. 2 is a perspective view of the transmission member as seen from the left side. [Figure 4] FIG. 4 is a cross-sectional view showing a state in which the ring gear is removed from the transmission member. [Figure 5] FIG. 2 is a cross-sectional view of a drive unit to which a transmission member is attached. [Figure 6] 1 is a schematic diagram of a hydroelectric power generation system. [Figure 7] FIG. 10 is a perspective view showing another example of a transmission member. [Figure 8] FIG. 8 is a cross-sectional view of FIG. [Figure 9] FIG. 10 is a cross-sectional view showing another example of a transmission member. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, one embodiment of a power transmission member according to the present invention will be described with reference to the drawings. In the example shown in this embodiment, this power transmission member is used when converting a drive unit of an electric vehicle into a hydroelectric power generation system. Below, an overview of the drive unit will be shown, followed by a description of the power transmission member and its conversion to a hydroelectric power generation system. Note that, for convenience of explanation, the following description will be given according to the directions indicated in the drawings, but the present invention is not limited to these directions.

[0012] <1. Overview of electric vehicle drivetrain> FIG. 1 is a cross-sectional view of a drive unit 1 for an electric vehicle. As shown in FIG. 1, the drive unit 1 includes a housing 11, which accommodates a differential gear 12. Although not shown, the housing 11 also accommodates a motor as a rotating electric machine, a reducer (transmission), and an inverter as a power conversion device. The inverter converts power between a battery and the motor. The output shaft of the motor is connected to the reducer. The output of the reducer is transmitted to the differential gear 12, which rotates the drive shafts of the wheels, not shown.

[0013] As shown in FIG. 1 , the housing 11 has an accommodation space 111 for the differential gear 12. A first through-hole 112 through which a drive shaft for a left wheel is inserted is formed on the left side of the accommodation space 111, and a second through-hole 113 through which a drive shaft for a right wheel is inserted is formed on the right side. The axes of these two through-holes 112, 113 are on the same line extending in the left-right direction. This axis is the axis of the drive shaft of the wheel and will be referred to as the rotation axis L hereinafter. The first through-hole 112 has a small-diameter first portion 112a and a large-diameter second portion 112b formed inside the housing 11, which are connected via an annular step. Similarly, the second through-hole 113 has a small-diameter first portion 113a and a large-diameter second portion 113b formed inside the housing 11, which are connected via an annular step.

[0014] The accommodation space 111 has a cylindrical first portion 111a and a conical second portion 111b formed contiguously to the right of the first portion 111a. The second portion 111b is formed between the first portion 111a and the second through-hole 113, and has a tapered surface such that the inner diameter gradually decreases from the first portion 111a toward the second through-hole 113.

[0015] The housing 11 is configured so as to be separable into a plurality of sections, such as a right and left section with an accommodation space 111 between them, for assembly purposes such as accommodating the differential gear 12.

[0016] The differential device 12 is rotatably supported in the accommodation space 111 and includes a differential case 121, a pair of side gears 122, a pair of pinion gears 123, a pinion shaft 124, and a ring gear 125. A flange 128 is formed on the outer peripheral surface of the differential case 121, and a ring gear 125 is fixed to this flange 128. The ring gear 125 is accommodated in a first portion 111a of the accommodation space 111 and rotates around a rotation axis L by a reducer. A cylindrical first journal portion 126 is formed at the left end of the differential case 121. The first journal portion 126 is disposed coaxially with the first through hole 112 of the housing 11 and is rotatably supported via a bearing (not shown) disposed in a second portion 112b of the first through hole 112. Meanwhile, a cylindrical second journal portion 127 is formed at the right end of the differential case 121. The second journal portion 127 is disposed coaxially with the second through-hole 113 of the housing 11, and is rotatably supported via a bearing (not shown) disposed in a second portion 113b of the second through-hole 113. In other words, the differential case 121 is rotatable around the rotation axis L within the accommodation space 111 via these two bearings.

[0017] A side gear 122 rotatably supported on an axial end of a first journal portion 126 is provided on the left side of the internal space of the differential case 121, and a side gear 122 rotatably supported on an axial end of a second journal portion 127 is provided on the right side of the internal space. These side gears 122 are rotatable around the rotation axis L described above within the differential case 121. A pinion shaft 124 is disposed in the differential case 121 between the side gears 122 so as to be perpendicular to the rotation axis L, and both ends of the pinion shaft 124 are rotatably supported by the differential case 121. Pinion gears 123 are fixed to both ends of the pinion shaft 124, respectively, and each pinion gear 123 is in mesh with both side gears 122.

[0018] <2. Conversion to hydroelectric power generation systems> When the drive device 1 is applied to a hydroelectric power generation system, the differential device 12 is replaced with a transmission member 2. In the following, the transmission member 2 will be described first, and then application to a hydroelectric power generation system will be described.

[0019] <2-1. Transmission components> Fig. 2 is a perspective view of the transmission member as seen from the right side, Fig. 3 is a perspective view of the transmission member as seen from the left side, and Fig. 4 is a cross-sectional view of the transmission member with the ring gear removed. As shown in Figs. 2 and 3, the transmission member 2 has a cylindrical shaft member 21, a disk-shaped support portion 22 connected to the shaft member 21, and a ring gear 23 connected to the support portion 22.

[0020] As shown in FIG. 4 , the shaft member 21 has a main body portion 211 and a connecting portion 212, which are integrally connected in the axial direction. The main body portion 211 has a first portion 2111, a second portion 2112, a third portion 2113, and a fourth portion 2114, which are integrally connected from right to left. The first portion 2111, the second portion 2112, and the third portion 2113 are formed so that their outer diameters increase in this order. The fourth portion 2114 has approximately the same outer diameter as the second portion 2112. The axial lengths of the first portion 2111 and the second portion 2112 are approximately the same and short, corresponding to the axial lengths of the first portion 113a and the second portion 113b of the second through-hole 113 of the housing 11, respectively. On the other hand, the axial length of the third portion 2113 is longer than the first and second portions 2111 and 2112. The axial length of the fourth portion 2114 is approximately the same as the total axial length of the first to third portions 2111 to 2113.

[0021] The above-mentioned support part 22 is fixed integrally to the vicinity of the left end part of the third part 2113. A plurality of through holes 221 are formed at predetermined intervals in the circumferential direction near the outer edge of this support part 22, and these through holes 221 and through holes formed in the ring gear 23 are fixed by bolts 24 as described below. The ring gear 23 is configured to mesh with a gear of a reducer accommodated in the housing 11.

[0022] The connecting portion 212 is a portion that is connected to a coupling of a hydroelectric power generation system, which will be described later. The connecting portion 212 is integrally connected to the left end of the fourth portion 2114, and is formed in a cylindrical shape with the same outer diameter as the fourth portion 2114. In addition, a key groove 213 that extends in the axial direction from near the boundary with the fourth portion 2114 is formed on the outer circumferential surface of the connecting portion 212, and this key groove 213 is connected to a coupling of a hydroelectric power generation system, which will be described later.

[0023] The shaft member 21 can be formed from a metal material such as iron, stainless steel, brass, copper, aluminum, high-speed steel, nickel-chromium steel, chromium-molybdenum steel, chromium steel, high-carbon chromium bearing steel, manganese steel, or chromium-molybdenum steel. The main body 211 and the connecting portion 212 have different surface hardnesses. That is, the Rockwell hardness (HRC) of the surface of the main body 211 is equal to or lower than the HRC of the surface of the connecting portion 212. For example, the ratio of the HRC of the main body 211 to the HRC of the surface of the connecting portion 212 is preferably 0.1 to 1.0. The HRC of the main body 211 and the connecting portion 212 is not particularly limited, but, for example, the HRC of the main body 211 is preferably 20 to 50. The HRC of the connecting portion 212 is preferably 50 to 80. The HRC of the support portion 22 can be the same as the HRC of the main body 211. The depth (effective hardened layer depth) of each portion where the above HRC is obtained is preferably 0.4 to 0.6 mm. Preferably, the HRC inside the main body portion 211 and the support portion 22 is 10 to 60, for example, and the HRC inside the connecting portion 212 is 40 to 90, for example.

[0024] To make the main body portion 211 and the connecting portion 212 have different HRCs, there is a method of making a difference in the time of quenching or tempering, but the method is not limited to this.

[0025] <2-2. How to use transmission components> Next, a method of using the power transmission member 2 configured as above will be described. Figure 5 is a cross-sectional view of the drive device 1 to which the power transmission member 2 is attached.

[0026] Before attaching the transmission member 2, first, the housing 11 shown in FIG. 1 is disassembled, and the differential gear 12 is removed. Then, the first bearing 31 is press-fitted into the second portion 2112 of the shaft member 21 of the transmission member 2. Similarly, the second bearing 32 is press-fitted into the fourth portion 2114 of the shaft member 21. This second bearing 32 is positioned so that it contacts the step at the boundary between the third portion 2113 and the fourth portion 2114.

[0027] Next, this power transmission member 2 is attached to the disassembled housing 11. That is, the first bearing 31 is fixed to the second portion 113b of the second through hole 113. Subsequently, the first oil seal 41 is placed in the first portion 113a of the second through hole 113 and fixed to the first portion 2111 of the shaft member 21 by crimping. At this time, the tip of the first portion 2111 slightly protrudes from the second through hole 113. In addition, the power transmission member 2 is arranged so that the ring gear 125 meshes with a gear of a reducer housed in the housing 11.

[0028] Next, the housing 11 is assembled. At this time, the second bearing 32 is fixed to the second portion 112b of the first through hole 112. Subsequently, the second oil seal 42 is placed in the first portion 112a of the first through hole 112, and the second oil seal 42 is fixed by crimping so as to be adjacent to the second bearing 32 at the fourth portion 2114 of the shaft member 21. In this way, as shown in FIG. 5 , the transmission member 2 is arranged in the drive device 1 in place of the differential device 12.

[0029] As shown in Fig. 5, the fourth portion 2114 and the connecting portion 212 of the transmission member 2 protrude to the left side of the housing 11. Of these protruding portions, the connecting portion 212 is connected to a coupling 51 that is connected to an impeller of a hydroelectric power generation system. That is, a key 511 provided on the coupling 51 fits into a key groove 213 of the connecting portion 212, thereby transmitting the rotation of the coupling 51 to the transmission member 2. In this way, by attaching the transmission member 2 to the drive device 1, a component of the power generation system is formed.

[0030] <2-3. Operation of Hydroelectric Power Generation System> FIG. 6 is a schematic diagram of an example of a hydroelectric power generation system. As shown in FIG. 6, this hydroelectric power generation system has an impeller 53 that rotates relative to the water flowing downward. The impeller 53 has a rotation shaft extending in the vertical direction, and the rotation of this rotation shaft is converted into rotation about a horizontal axis via an orthogonal gearbox 52. This rotation is then transmitted to a transmission member 2 of a drive unit 1 via a coupling 51. In the drive unit 1, the rotation of the transmission member 2 is transmitted to a motor via a reducer, causing the motor to rotate. This generates electricity. The generated electricity is stored in a power storage device 7 via an inverter. In this way, the drive unit 1 of an electric vehicle is converted into a hydroelectric power generation system. The impeller 53, the orthogonal gearbox 52, and the coupling 51 are an example of a drive source of the present invention.

[0031] <3. Features> In this embodiment, the following effects can be obtained. (1) The transmission member 2 described above is formed by assembling the ring gear 23 to the integrally constructed shaft member 21 and support portion 22. Therefore, unlike a differential lock in which the gears of a differential device are fixed by welding, the transmission member 2 does not disassemble due to deterioration over time. Therefore, it is possible to prevent energy loss due to deterioration over time when transmitting the rotational force transmitted from the coupling 51 of the hydroelectric power generation system to the drive unit 1.

[0032] (2) One method of locking the differential is to fit a differential locking jig into the differential mechanism, but in this case, the differential device 12 must be removed from the housing 11, and then disassembled and reassembled, which is a time-consuming process. In contrast, in this embodiment, by replacing the differential device 12 with the transmission member 2, the system can be easily adapted for use in a hydroelectric power generation system.

[0033] As described above, by using the transmission member 2 of this embodiment, even the drive device 1 for an electric vehicle having the differential gear 12 built in can be effectively converted into a power generation system.

[0034] (3) The transmission member 2 is composed of the connecting portion 212 with a high surface HRC, and the main body portion 211 and support portion 22 with a low surface HRC. Therefore, the following effect can be obtained. When the driving device 1 configured as described above is diverted to a hydroelectric power generation system, the power from the impeller 53 is accelerated by the reducer and transmitted to the motor, so the rotation speed of the power input to the transmission member 2 is lower than the rotation speed output from the transmission member 2 to the reducer. Therefore, a large torque acts on the connecting portion 212, which may cause breakage at the connecting portion.

[0035] To verify this point, power transmission members 2 were produced in Examples 1 to 8 and Comparative Examples 1 and 2. The dimensions of these power transmission members 2 are all the same, as shown in Table 1 below. [Table 1]

[0036] However, the transmission member 2 was made of chromium molybdenum steel (SCM440). The HRC of each part was adjusted as follows. Specifically, the connecting part 212 was induction hardened and tempered to create a difference in HRC from the main body part 211 and the support part 22. [Table 2] The effective depth of HRC on the surface of each part was 0.4 to 0.6 mm, the HRC inside the main body part 211 and the support part 22 was 10 or more, and the HRC inside the connecting part 212 was 50 or more.

[0037] A torque of 986 Nm was applied to the connecting portion 212 of the transmission member 2 configured as above, and each transmission member 2 was rotated at 213 rpm. As a result, the ring gear 23 transmitted rotational force to the reducer with a torque of 120 Nm. The above test was conducted for more than 87,600 hours, and the results are as follows.

[0038] [Table 3]

[0039] As shown in Table 3, no fracture of the transmission member 2 was observed in Examples 1 to 8. On the other hand, in Comparative Example 1, fracture occurred near the attachment portion of the ring gear 23 on the support portion 22. This is thought to be because the HRC of the surfaces of the main body portion 211 and the support portion 22 is low, resulting in an imbalance in the difference in HRC. Furthermore, in Comparative Example 2, fracture occurred at the connecting portion connected to the coupling of the hydroelectric power generation system. This is thought to be because, as described above, the torque acting on the connecting portion 212 is large, while the HRC of the surface of the connecting portion 212 is low, resulting in an imbalance in the difference in HRC. Therefore, it was found that the ratio of HRC(a) of the surfaces of the main body portion 211 and the support portion 22 to HRC(b) of the surface of the connecting portion 212 is preferably 0.1 to 1.0.

[0040] <4. Modifications> Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications are possible without departing from the spirit of the present invention. For example, the following modifications are possible. Furthermore, the gist of the following modifications can be appropriately combined with each other and can also be combined with the above embodiment.

[0041] (1) In the above embodiment, the main body 211 of the shaft member 21 is configured by four sections 2111 to 2114 having different outer diameters and axial directions, but this is not limited to this. That is, the length and diameter of each section of the main body 211 of the shaft member 21 can be changed as appropriate. The number of sections can also be changed as appropriate; for example, the main body 211 may be configured with the same outer diameter. That is, it is sufficient that the shaft member 21 is configured so that it can be connected to the housing 11 via the bearings 31 and 32 and so that the oil seals 41 and 42 can be attached.

[0042] (2) In the above embodiment, the shaft member 21 is composed of the main body 211 and the connecting portion 212, whose surfaces have different HRCs. However, the axial length of the connecting portion 212 is not particularly limited as long as it is long enough to accommodate a coupling for a hydroelectric power generation system. Furthermore, the entire surface of the shaft member 21 may have the same HRC.

[0043] (3) The shaft member 21 can also be composed of multiple separable members. For example, as shown in Fig. 7, the shaft member 21 can be composed of a main body portion 201 and a connecting portion 202. The main body portion 201 corresponds to the above-described main body portion 211, but a cylindrical fifth portion 2115 with a small outer diameter is integrally connected to the rear portion of the fourth portion 2114. The connecting portion 202 is formed in a cylindrical shape with an outer diameter larger than that of the fourth portion 2114, and is formed at its front end with a cylindrical recess 261 into which the fifth portion 2115 is inserted. The connecting portion 202 and the fifth portion 2115 are connected by a key 262. A key groove 263 is formed on the outer peripheral surface of the connecting portion 202.

[0044] With this configuration, if multiple connecting portions 26 corresponding to the couplings 51 to be connected are prepared in advance, there is no need to process the shaft member 21 to fit the couplings 51, and the installation work of the power transmission member 2 can be easily performed. The structure of the connecting portions is not particularly limited as long as it is a form that matches the coupling. The connecting structure between the connecting portions 202 and the main body portion 201 is also not particularly limited and can be modified in various ways. As with the connecting portion 212 described above, the HRC of the surface of the connecting portion 202 can be made higher than the HRC of the surface of the main body portion 211.

[0045] (4) As shown in Figures 8 and 9, a vibration-damping weight 28 can also be attached to the transmission member 2. The weight 28 is formed in a cylindrical shape having a through hole 281 through which the shaft member 21 is inserted, and is fixed to the front surface of the support part 22 with a bolt 283. The through hole 281 of the weight and the shaft member 21 are connected with a key 218. A tapered surface 282 is formed on the outer circumferential surface of the weight 28, the outer diameter of which decreases toward the right. The tapered surface 282 has a shape that corresponds to the tapered surface formed on the second portion 111b of the housing 11.

[0046] The provision of such weight 28 can mitigate the influence on vibration damping control of the motor. In particular, the difference between the outer shape of transmission member 2 and the outer shape of differential case 121 of differential device 12 is reduced, filling the gap with respect to when drive device 1 is used for a vehicle, and further mitigating the influence on vibration damping control of the motor.

[0047] The shape of the weight 28 is not particularly limited, and can be changed as appropriate to suit the drive device 1 to which it is to be attached, such as to accommodate vibration control. The method of attaching the weight 28 to the transmission member 2 is also not particularly limited, as long as the weight 28 is attached to at least one of the support part 22 and the shaft member 21. The attachment position of the weight 28 is also not particularly limited, and it can be attached to the rear side of the support part 22. Furthermore, the weight 28 can be attached to both the front side and the rear side of the support part 22.

[0048] (5) The configuration of the drive unit 1 shown in the above embodiment is an example and can be modified as appropriate. For example, in the above embodiment, the housing 11 accommodates the inverter, motor (rotating electric machine), reducer, and differential gear 12. However, it is sufficient that at least the reducer and differential gear are accommodated, and the motor and inverter can also be disposed outside the housing 11 (for example, in another housing). Furthermore, multiple housings may be connected to accommodate at least the motor, reducer, and differential gear.

[0049] (6) The configuration of the hydroelectric power generation system shown in Fig. 6 is one example, and various modifications are possible. In the example of Fig. 6, an orthogonal gearbox 52 is provided because an impeller 53 that rotates due to water flowing downward is provided, but if the impeller 53 rotates around an axis extending horizontally, such an orthogonal gearbox 52 is not necessary. Also, an electromagnetic clutch or the like can be provided to disconnect the drive unit 1 and the coupling 51, as necessary.

[0050] Furthermore, the present invention is applicable to systems other than hydroelectric power generation systems, and is applicable to any power generation system that generates electricity by rotating a single turbine shaft, such as a wind power generation system. [Explanation of symbols]

[0051] 1: Drive unit 2: Transmission member 11 Housing 12: Differential device 21: Shaft member 22: Support part 28: Weight 111: Containment Space 113:Through hole 201: Main body part 211: Main body 212: Connection part

Claims

1. In a drive device for an electric vehicle including a housing that accommodates at least a transmission and a differential gear, a transmission member that is accommodated in the housing in place of the differential gear and transmits power from a drive source of a power generation system, a shaft member connectable to the drive source; a support portion fixed to the shaft member and extending radially from the shaft member; a gear fixed to the support portion and configured to transmit power to the transmission; Equipped with a transmission member, the shaft member being rotatably fixed to the housing so as to coincide with the rotation axis of the differential device, and configured to transmit rotational power from the gears to the transmission;

2. the shaft member has a main body portion to which the support portion is fixed, and a coupling portion that is coaxially coupled to the main body portion and is connectable to the drive source, 2. The power transmission member according to claim 1, wherein the ratio of the Rockwell hardness of the surface of said body portion to the Rockwell hardness of the surface of said connecting portion is 0.1 to 1.

0.

3. The power transmission member according to claim 1 or 2, further comprising a vibration-damping weight attached to the support portion or the shaft member.

4. the shaft member includes a main body portion to which the support portion is attached, and an exchange portion detachably fixed to an axial end portion of the main body portion, The power transmission member according to claim 1 or 2, wherein the replacement portion is connectable to a driving source of the power generation system.

5. A component of a power generation system, comprising a housing for accommodating at least a transmission and a differential gear, and the transmission member according to claim 1 or 2 attached to a drive gear of an electric vehicle in place of the differential gear.

6. A method for converting a drive unit of an electric vehicle, including a housing that accommodates at least a transmission and a differential, into a component of a power generation system, comprising: removing the differential gear from an accommodation space of the differential gear in the housing; The transmission member according to claim 1 is accommodated in the housing, the shaft member is rotatably fixed to the housing so as to coincide with the rotation axis of the differential device, and the shaft member is connected so as to transmit rotational power from the gears to the transmission; connecting a driving source of the power generation system to one end of the shaft member protruding from the housing; A method for repurposing a drive unit of an electric vehicle, comprising:

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