JP6148922B2 - Left and right wheel drive - Google Patents

Description

  The present invention relates to a left and right wheel drive device capable of transmitting drive torque from two independent drive sources while giving a torque difference to left and right drive wheels, and particularly to an electric vehicle having a drive source as an electric motor. The present invention relates to a right-and-left wheel drive device suitable for use.

  In a vehicle such as an electric vehicle, electric motors (electric motors) are arranged on the left and right drive wheels, respectively, and each motor is controlled independently to give an appropriate drive torque difference to the left and right wheels, thereby turning the vehicle's turning moment A technique for controlling the above is known. For example, when each electric motor is independently connected to the left and right driving wheels via a gear mechanism or the like, the output torque of each electric motor becomes the driving torque of the left and right driving wheels as it is. Therefore, in order to give a drive torque difference between the left and right wheels, it is necessary to give a torque difference equal to the drive torque difference to be given between the motors. In other words, a driving torque difference greater than the torque difference between the motors cannot be given between the left and right wheels.

  On the other hand, for example, Patent Document 1 discloses two sets of reduction gears each composed of a combination of two differential devices each using a planetary gear mechanism and a plurality of gears between output shafts of two drive sources. A driving force distribution device that includes a gear train is disclosed. In this technology, a three-element two-degree-of-freedom single pinion planetary gear mechanism is combined to realize a four-element two-degree-of-freedom device, and a part of the drive torque distributed to either the left or right drive wheel Can be moved to the other drive wheel.

  Patent Document 2 discloses a left and right wheel drive device in which a gear mechanism is interposed between two drive sources and left and right drive wheels. In this device, a four-element two-degree-of-freedom planetary gear mechanism is used, which includes a continuous pinion in which a plurality of pinion gears are connected to one shaft and four elements that are linked to the continuous pinion. It is connected to each drive source and left and right drive wheels in a corresponding relationship. Thereby, when a difference is given to the torque output from the two drive sources, this torque difference is amplified and can be transmitted to the left and right drive wheels.

Japanese Patent No. 4907390 JP 2011-237019 A

  However, in the apparatus of Patent Document 1 described above, when two planetary gear mechanisms are arranged coaxially, a shaft connecting the ring gear R1 and the carrier C2 between the two planetary gear mechanisms, the carrier C1 and the ring gear is provided. A shaft connecting R2 and a shaft connecting the sun gear S1 and the first electric motor M1 pass. That is, in this device, the shaft passing between the two planetary gear mechanisms has a triple structure, and the structure for supporting the shaft may be complicated. Therefore, an increase in cost is inevitable in order to obtain a shaft support structure that ensures rigidity and accuracy. Moreover, in the apparatus of Patent Document 2, the planetary gear mechanism requires a high work accuracy for the continuous pinion and the like, and thus there is a problem that the manufacturing cost increases.

  For example, in order to realize smooth turning of the vehicle and to suppress changes in vehicle behavior such as understeer and oversteer, it is generally effective to generate a large drive torque difference between the left and right drive wheels. For this reason, it is desired that the torque difference amplification factor for amplifying the difference between the torques output from the two drive sources be a large value.

  The present invention has been devised in view of such problems, and an object thereof is to provide a left and right wheel drive device capable of reducing costs while obtaining a relatively large torque difference amplification factor. The present invention is not limited to this purpose, and is a function and effect derived from each configuration shown in the embodiments for carrying out the invention described later, and other effects of the present invention are to obtain a function and effect that cannot be obtained by conventional techniques. Can be positioned.

(1) A left and right wheel drive device disclosed herein includes two drive sources mounted on a vehicle and independently controllable, left and right drive wheels, and between the two drive sources and the left and right drive wheels. And a gear device formed by combining two planetary gear mechanisms with three elements and two degrees of freedom on the same axis.
Each of the planetary gear mechanisms is provided with a sun gear as a first rotating body for input, a second rotating body for output provided coaxially with the sun gear, and provided with the sun gear, A third rotating body that rotates in a direction opposite to the sun gear when the rotating body is fixed.

  The gear device includes a first coupling element in which one sun gear and the other third rotating body are coupled, and a second coupling element in which one third rotating body and the other sun gear are coupled. Have One of the driving sources is connected to the first coupling element, and the other driving source is connected to the second coupling element. Further, one of the driving wheels is connected to one of the second rotating bodies, and the other driving wheel is connected to the other second rotating body.

  That is, in the gear device, since the sun gears of the two planetary gear mechanisms are the first coupling element and the second coupling element, the first coupling element and the second planetary gear mechanism are between the two planetary gear mechanisms. It becomes a double structure through which only two axes of the two coupling elements pass.

(2) It is preferable that the gear device is configured by combining two double pinion planetary gear mechanisms in which the second rotating body is a ring gear and the third rotating body is a carrier.
(3) Alternatively, the gear device is preferably configured by combining two single pinion planetary gear mechanisms in which the second rotating body is a carrier and the third rotating body is a ring gear.

(4) The gear device includes a hollow shaft in which the first coupling element and the second coupling element are coaxially arranged, one of which includes a solid shaft and the other of which the solid shaft is inserted. The shaft passing between the two planetary gear mechanisms is preferably a double structure.
(5) At this time, the solid shaft is provided with one end being the rotation shaft of the one sun gear and the other end penetrating the center of the other sun gear, and connecting the two planetary gear mechanisms. More preferred.
(6) Preferably, the two drive sources are both electric motors.

  According to the disclosed left and right wheel drive device, the shaft passing between the two planetary gear mechanisms can have a double structure, so that rigidity and accuracy can be ensured without complicating the shaft support structure. Further, the structure can be simplified as compared with the case of using a continuous pinion type or Ravigneaux type planetary gear mechanism. Therefore, the cost can be reduced while obtaining a relatively large torque difference amplification factor.

It is a skeleton figure which shows the left-right wheel drive device which concerns on 1st embodiment. It is a figure for demonstrating the double pinion planetary gear mechanism used for the left-right drive wheel apparatus which concerns on 1st embodiment, (a) is a front view shown with the pitch circle diameter, (b) is a velocity diagram. is there. It is a speed diagram for demonstrating the torque difference amplification factor by the gear apparatus of the left-right wheel drive device which concerns on 1st embodiment. FIG. 2 is a skeleton diagram showing only one side of the shaft center by omitting the reduction gear train from the left and right wheel drive device according to the first embodiment, wherein (a) corresponds to FIG. 1 and (b) is a modification of the layout. is there. (A)-(c) is a skeleton figure which abbreviate | omits a reduction gear train from the right-and-left wheel drive device which concerns on 2nd embodiment, and shows only one side of an axial center. It is a figure for demonstrating the single pinion planetary gear mechanism used for the left-right wheel drive device which concerns on 2nd embodiment, (a) is a front view shown with the pitch circle diameter, (b) is a velocity diagram. is there. It is a speed diagram for demonstrating the torque difference amplification factor by the gear apparatus of the left-right wheel drive device which concerns on 2nd embodiment.

  Hereinafter, embodiments will be described with reference to the drawings. Note that the embodiment described below is merely an example, and there is no intention to exclude various modifications and technical applications that are not explicitly described in the following embodiment. Each configuration of the present embodiment can be implemented with various modifications without departing from the spirit of the present embodiment, and can be selected or combined as necessary.

[1. First embodiment]
[1-1. overall structure]
First, the overall configuration of the left and right wheel drive device according to the present embodiment will be described with reference to FIG. The left and right wheel drive device 1 includes a first motor 2 and a second motor 3 (two drive sources) mounted on a vehicle such as an automobile, a left drive wheel 4L, and a right drive wheel 4R (left and right drive wheels). And a gear unit 5 and reduction gear trains 6 and 7 interposed therebetween.

  The first motor 2 and the second motor 3 are electric motors (hereinafter also simply referred to as motors) that operate by supplying power from a battery (not shown) mounted on the vehicle, and are individually controlled by an electronic control device (not shown). Thus, it is possible to generate and output different torques. Here, the first motor 2 and the second motor 3 are motors of the same standard having the same maximum output. The vehicle is an electric vehicle or a hybrid electric vehicle using the first motor 2 and the second motor 3 as drive sources. The output shaft 2a of the first motor 2 and the output shaft 3a of the second motor 3 are connected to respective coupling elements 11 and 12 of the gear device 5 described later via reduction gear trains 6 and 7, respectively.

  The first reduction gear train 6 is interposed between the first motor 2 and the gear device 5, and reduces the rotational speed of the first motor 2 and outputs (transmits) it to the gear device 5. The second reduction gear train 7 is interposed between the second motor 3 and the gear device 5, and similarly reduces the rotational speed of the second motor 3 and outputs (transmits) it to the gear device 5. is there. The torques TM1 and TM2 generated by the first motor 2 and the second motor 3 are transmitted to the left and right drive wheels 4L and 4R via the gear device 5.

[1-2. Gear device]
The gear device 5 is configured by combining two identical planetary gear mechanisms 10A and 10B having three elements and two degrees of freedom on the same axis. In the present embodiment, a double pinion planetary gear mechanism as shown in FIG. 2A is adopted for each of the planetary gear mechanisms 10A and 10B. As shown in FIG. 2A, the double pinion planetary gear mechanism is provided coaxially between the sun gear S and the ring gear R of the same module provided on the same axis, and between the sun gear S and the ring gear R. Carrier C and two pinion gears P that are rotatably supported by the carrier C and mesh with each other. One pinion gear P meshes with the sun gear S, and the other pinion gear P meshes with the ring gear R.

The number of teeth Z _S of the sun gear _S is set to approximately half of the number of teeth Z _R of the ring gear R (that is, Z _S : Z _R ≈1: 2). Further, since the proportional and number of teeth and the pitch diameter ratio of the pitch circle diameter D _R of the pitch circle diameter D _S and the ring gear R of the sun gear S is about 1: 2. The reason why the relationship between the sun gear S and the ring gear R is set as Z _S : Z _R = D _S : D _R ≈1: 2 is that the balance between strength and space is taken into consideration.

That is, when the pitch circle diameter D _S of the sun gear S is too large, it becomes impossible to two disposed pinion gear P between the sun gear S and the ring gear R, the pitch circle diameter D _S of the sun gear S is too small on the opposite ( This is because if the number of teeth Z _S is too small, the number of times the same teeth mesh with each other increases, and the strength of the gear may be reduced. Therefore, by setting the sun gear S and the ring gear R in the above relationship, the strength is ensured while being realized as a gear mechanism. Note that the number of teeth Z _P (or pitch circle diameter) of the pinion gear _P is set to a number (or size) that can be realized as a double pinion planetary gear mechanism. Here, a plurality of sets (three sets in FIG. 2A) of the pinion gears P are provided and the transmission force is dispersed, so that a gear having a small diameter and a small number of teeth can be employed.

A speed diagram in such a double pinion planetary gear mechanism is shown in FIG. In the double pinion planetary gear mechanism, when the carrier C is fixed, the sun gear S and the ring gear R rotate in the same direction. Therefore, in the speed diagram, the ring gear R and the sun gear S are on the same side with respect to the carrier C (in the figure, On the left). In other words, the carrier C is disposed on the opposite side of the sun gear S across the ring gear R, and when the ring gear R is fixed, the sun gear S and the carrier C rotate in opposite directions. The ratio of the length from the carrier C to the ring gear R and the length from the carrier C to the sun gear S is the reciprocal of the number of teeth Z _R of the ring gear R (1 / Z _R ) and the reciprocal of the number of teeth Z _S of the sun gear S (1 / Is equal to the ratio to Z _S ).

  As shown in FIG. 1, a gear device 5 according to the present embodiment includes a first planetary gear mechanism having a sun gear S1 (first rotating body), a ring gear R1 (second rotating body), and a carrier C1 (third rotating body). 10A and a second planetary gear mechanism 10B having a sun gear S2 (first rotating body), a ring gear R2 (second rotating body) and a carrier C2 (third rotating body) are coaxially combined. .

  Specifically, the sun gear S1 of the first planetary gear mechanism 10A and the carrier C2 of the second planetary gear mechanism 10B are coupled to form the first coupling element 11, and the carrier C1 of the first planetary gear mechanism 10A and the second The planetary gear mechanism 10B and the sun gear S2 are coupled to form the second coupling element 12. Torque TM1 generated by the first motor 2 is input to the first coupling element 11, and torque TM2 generated by the second motor 3 is input to the second coupling element 12. The ring gear R1 of the first planetary gear mechanism 10A is connected to the left drive wheel 4L, and the ring gear R2 of the second planetary gear mechanism 10B is connected to the right drive wheel 4R.

  The first coupling element 11 includes a hollow shaft extending along the axis of the gear device 5, and the second coupling element 12 is inserted through the hollow coupling shaft 11. The second coupling element 12 includes a solid shaft that extends along the axis of the gear device 5, and the first coupling element 11 and the second coupling element 12 are arranged coaxially. The second coupling element 12, which is a solid shaft, has one end (right end in the figure) serving as the rotation shaft of the sun gear S2, and the other end (left end in the figure) penetrating the sun gear S1 to provide two planetary gear mechanisms. 10A and 10B are connected. In addition, as for the 1st coupling element 11 which is a hollow shaft, one end (left end in a figure) is a rotating shaft of the sun gear S1.

  Only the two shafts of the first coupling element 11 and the second coupling element 12 pass between the first planetary gear mechanism 10A and the second planetary gear mechanism 10B. That is, between the first planetary gear mechanism 10A and the second planetary gear mechanism 10B, there is a double structure of only the first coupling element 11 and the second coupling element 12, and the two planetary gear mechanisms 10A, 10B. In between, these two shafts are supported by bearings (not shown).

  Here, the driving torque transmitted by the gear device 5 will be described with reference to a velocity diagram shown in FIG. Since the gear device 5 is configured by combining two identical double pinion planetary gear mechanisms 10A and 10B, it can be represented by two velocity diagrams as shown in FIG. Here, for easy understanding, the two speed diagrams are shifted up and down, the speed diagram of the first planetary gear mechanism 10A is shown on the upper side, and the speed diagram of the second planetary gear mechanism 10B is shown on the lower side.

  Further, in the velocity diagram of the first planetary gear mechanism 10 </ b> A and the velocity diagram of the second planetary gear mechanism 10 </ b> B, the sun gear S and the carrier C are arranged opposite to each other (become left-right symmetry). That is, in FIG. 3, the carrier C2 of the second planetary gear mechanism 10B is disposed under the sun gear S1 of the first planetary gear mechanism 10A, and the second planetary gear mechanism 10B is disposed under the carrier C1 of the first planetary gear mechanism 10A. A sun gear S2 is arranged.

  In the gear device 5, the elements located at both ends of the two velocity diagrams shown in FIG. 3 are joined to each other as shown by a broken line in the figure to form a first joining element 11 and a second joining element 12. The The torques TM1 and TM2 output from the first motor 2 and the second motor 3 are input to the first connecting element 11 and the second connecting element 12, respectively. On the other hand, drive torques TL and TR transmitted to the left and right drive wheels 4L and 4R from the ring gears R1 and R2 located in the middle on the speed diagram are output.

According to the gear device 5 configured in this way, a torque difference (input torque difference) ΔT _IN (= TM2−TM1) is given to each of the torques TM1 and TM2 generated by the first motor 2 and the second motor 3. A torque difference (drive torque difference) ΔT _OUT (= TL−TR) can be generated between the drive torque TL transmitted to the left drive wheel 4L and the drive torque TR transmitted to the right drive wheel 4R. In other words, the distribution of the driving force transmitted to the left and right driving wheels 4L, 4R can be manipulated.

That is, according to the gear device 5, the relationship of the following formula (1) is obtained.
ΔT _OUT = α × ΔT _IN (1)
Here, the coefficient alpha, a torque difference amplification factor for amplifying the input torque difference [Delta] T _IN, as this value is larger, it is possible to obtain a large driving torque difference [Delta] T _OUT even small input torque difference [Delta] T _IN.

  The torque difference amplification factor α of the gear device 5 according to the present embodiment will be described. Here, since the two double pinion planetary gear mechanisms 10A and 10B use gear elements having the same number of teeth, the distance between the carrier C1 and the ring gear R1 and the distance between the carrier C2 and the ring gear R2 are equal. Is a. Further, the distance between the sun gear S1 and the ring gear R1 and the distance between the sun gear S2 and the ring gear R2 are also equal, which is b. Torques TM1 and TM2 of the first motor 2 and the second motor 3 are input to the first coupling element 11 and the second coupling element 12 at the left and right ends, respectively, and drive torques TL and TR are taken out from the ring gears R1 and R2.

From the relationship between torque input and output, the following equation (2) is established.
TR + TL = TM1 + TM2 (2)
Moreover, the formula of the moment on the basis of the left end (C1, S2 portion) in the figure is the following formula (3).
0 = aTL + bTR-(a + b) TM1 (3)
From these formulas (2) and (3), TL and TR can be summarized as the following formulas (4) and (5).

From these equations (4) and (5), the drive torque difference ΔT _OUT is expressed by the following equation (6).

In the case of a double pinion planetary gear mechanism, the length a is the reciprocal number (1 / Z _R ) of the number of teeth Z _R of the ring gear R, and the length a + b is the reciprocal number of the number of teeth Z _S of the sun gear S (1 / Z _S ). Therefore, the above equation (6) can be rewritten as the following equation (7).

  That is, the torque difference amplification factor α is expressed by the following equation (8).

In the double-pinion planetary gear mechanism as described above, approximately the ratio between the number of teeth Z _R of the number of teeth Z _S and the ring gear R of the sun gear S 1: For a 2, a small value of the denominator close to zero equation (8) It becomes. Therefore, according to the gear device 5, since the torque difference amplification factor α can be increased, a large drive torque difference ΔT _OUT can be obtained even with a small input torque difference ΔT _IN . Incidentally, the number of teeth Z _S and the ring gear ratio between the tooth number Z _R of R is just one of the sun gear S: When 2 is set, for the denominator of Equation (8) becomes 0, in this embodiment, The number of teeth Z _S of the sun gear _S is set to a value slightly larger or slightly smaller than half of the number of teeth Z _R of the ring gear R.

  4 (a) and 4 (b) show skeleton diagrams in which the reduction gear trains 6 and 7 are omitted. Here, only one side of the shaft center of the gear mechanism is shown. FIG. 4A corresponds to the left and right wheel drive device 1 of FIG. On the other hand, FIG. 4B is a modification of the layout of the left and right wheel drive device 1 of FIG. 4A, and the connection parts of the two planetary gear mechanisms 10A and 10B are the same.

  In the example of FIG. 4B, compared with the layout of FIG. 4A, the two electric motors 2 and 3 are arranged on the outer side in the axial direction, and the two planetary gear mechanisms 10A and 10B are arranged close to each other. . The second coupling element 12 includes a hollow shaft that extends along the axis of the gear device 5, and the first coupling element 11 is inserted through the second coupling element 12. The first coupling element 11 includes a solid shaft extending along the axis of the gear device 5, and the first coupling element 11 and the second coupling element 12 are arranged coaxially.

  The first coupling element 11, which is a solid shaft, has one end (left end in the drawing) serving as the rotation shaft of the sun gear S 1, and the other end (right end in the drawing) penetrating the sun gear S 2. 10A and 10B are connected. Note that one end (the right end in the figure) of the second coupling element 12 that is a hollow shaft is a rotating shaft of the sun gear S2. Between the first planetary gear mechanism 10 </ b> A and the second planetary gear mechanism 10 </ b> B, there is a double structure through which only two axes of the first coupling element 11 and the second coupling element 12 pass. The left and right wheel drive device 1 can be mounted on a vehicle with a layout as shown in FIGS. 4 (a) and 4 (b). Other layouts may be used.

[1-3. effect]
Therefore, according to the left and right wheel drive device 1 according to the present embodiment, the two shafts of the first coupling element 11 and the second coupling element 12 pass between the two planetary gear mechanisms 10A and 10B. That is, it can be a double structure of the first coupling element 11 and the second coupling element 12. Thus, rigidity and accuracy can be ensured between the two planetary gear mechanisms 10A and 10B without complicating the structure for supporting these two shafts. Further, the structure of the gear device 5 can be simplified as compared with the case where a planetary gear mechanism of a continuous pinion type or Ravigneaux type is used.

Further, when different torques TM1 and TM2 are generated by the two motors 2 and 3, and the input torque difference ΔT _IN is given, the input torque difference ΔT _IN is amplified in the gear unit 5, and the driving torque larger than the input torque difference ΔT _IN is obtained. A difference ΔT _OUT can be obtained. That is, even with a small input torque difference [Delta] T _IN, the gear 5 can amplify the input torque difference [Delta] T _IN at a predetermined torque difference amplification factor alpha, is transmitted to a left driving wheel 4L and a right driving wheel 4R A driving torque difference ΔT _OUT larger than the input torque difference ΔT _IN can be given to the driving torques TL and TR.
Therefore, the cost can be reduced while obtaining a relatively large torque difference amplification factor α.

Further, in the left and right wheel drive device 1 described above, the gear device 5 is configured by combining two double pinion planetary gear mechanisms 10A and 10B, and therefore the torque difference amplification factor α is expressed by the above equation (8). . Further, in the double-pinion planetary gear mechanism, a ratio of the number of teeth Z _R of the number of teeth Z _S and the ring gear R of the sun gear S is about 1: To 2 is set to a small value of the denominator close to zero equation (8) Thus, the torque difference amplification factor α can be set to a large value.

For example, 30 number of teeth Z _S of the sun gear S, by setting the number of teeth Z _R of the ring gear R to 75, it can be 5 to torque difference amplification factor alpha, 30 number of teeth Z _S of the sun gear S, a ring gear If the number of teeth Z _R of _R is set to 72, the torque difference amplification factor α can be set to 6. Further, the number of teeth Z _S of the sun gear S 30, by setting the number of teeth Z _R of the ring gear R 66 can be a 11 a torque difference amplification factor alpha.

That is, according to the left and right wheel drive apparatus 1 described above, a sufficiently large drive torque difference ΔT _OUT between the left and right drive wheels 4L and 4R can be obtained even with a small input torque difference ΔT _IN . Also, simply by changing the ratio between the number of teeth Z _R of the number of teeth Z _S and the ring gear R of the sun gear S, can be obtained α torque difference gain of the various values. In other words, the left and right wheel drive device 1 with a high degree of freedom in setting the torque difference gain α can be obtained.

  Further, in the left and right wheel drive device 1 described above, the first coupling element 11 and the second coupling element 12 are arranged coaxially, one is configured to include a solid shaft, and the other is inserted through the solid shaft. This includes a hollow shaft. As a result, the shaft passing between the two planetary gear mechanisms 10A and 10B can have a double structure, the shaft support structure can be simplified, and the radial dimension of the gear device 5 can be reduced. It can be downsized.

  Further, the solid shaft has a simple configuration because one end thereof is a rotating shaft of one sun gear and the other end is provided through the other sun gear to connect the two planetary gear mechanisms 10A and 10B. Therefore, the structural reliability can be improved. Moreover, since the gear apparatus 5 can also be reduced in weight, the weight of the left-right wheel drive measure 1 whole can be reduced.

Further, in the left and right wheel drive device 1 described above, since the two electric motors 2 and 3 are used as drive sources, the input torque difference ΔT _IN can be easily generated. Further, if the first motor 2 and the second motor 3 are motors of the same standard having the same maximum output, it is only necessary to mount two of the same motors, which leads to cost reduction and the left and right drive wheels 4L, 4R. Torque control can also be performed in a simple and balanced manner.

[2. Second embodiment]
[2-1. Constitution]
Next, the left and right wheel drive device 1 ′ according to the second embodiment will be described with reference to FIGS. 5 to 7. The left and right wheel drive device 1 ′ is the same as the structure of the first embodiment except for the configuration of the gear device 8. Hereinafter, parts and structures similar to those of the first embodiment are denoted by the same reference numerals as those of the first embodiment, and redundant description is omitted.

  As shown in FIGS. 5A to 5C, the gear device 8 according to the present embodiment is configured by combining two identical planetary gear mechanisms 20A and 20B having three elements and two degrees of freedom on the same axis. Yes. 5 (a) to 5 (c) differ only in layout, and the connection parts of the two planetary gear mechanisms 20A and 20B are the same. In the present embodiment, a single pinion planetary gear mechanism as shown in FIG. 6A is employed for each of the planetary gear mechanisms 20A and 20B.

  As shown in FIG. 6A, the single pinion planetary gear mechanism is provided coaxially between the sun gear S and the ring gear R of the same module provided on the same axis, and between the sun gear S and the ring gear R. Carrier C and a single pinion gear P that is rotatably supported by the carrier C. The pinion gear P meshes with the sun gear S and the ring gear R.

Also in the single pinion planetary gear mechanism, the number of teeth Z _S of the sun gear _S is set to substantially half of the number of teeth Z _R of the ring gear R, and the pitch circle diameter DS of the sun gear _S and the ring gear are similar to the above-described double pinion planetary gear mechanism. The ratio of R to the pitch circle diameter D _R is about 1: 2. In addition, the number of teeth Z _P (or pitch circle diameter) of the pinion gear _P is set to a number (or size) that can be realized as a single pinion planetary gear mechanism.

A speed diagram in such a single pinion planetary gear mechanism is shown in FIG. In the single pinion planetary gear mechanism, when the carrier C is fixed, the sun gear S and the ring gear R rotate in opposite directions. Therefore, the ring gear R and the sun gear S are arranged on the opposite side with respect to the carrier C in the speed diagram. The In other words, the ring gear R is disposed on the opposite side of the sun gear S across the carrier C. The ratio of the length from the carrier C to the ring gear R and the length from the carrier C to the sun gear S is the same as above, with the reciprocal of the number of teeth Z _R of the ring gear R (1 / Z _R ) and the number of teeth Z _S of the sun gear S It is equal to the ratio to the reciprocal (1 / Z _S ).

  As shown in FIGS. 5A to 5C, the gear device 8 according to the present embodiment includes a sun gear S1 (first rotating body), a carrier C1 (second rotating body), and a ring gear R1 (third rotating body). And a second planetary gear mechanism 20B having a sun gear S2 (first rotating body), a carrier C2 (second rotating body), and a ring gear R2 (third rotating body) are coaxially arranged. It is configured in combination.

  Specifically, the sun gear S1 of the first planetary gear mechanism 20A and the ring gear R2 of the second planetary gear mechanism 20B are coupled to form a first coupling element 21, and the ring gear R1 of the first planetary gear mechanism 20A and the second gear R2 are coupled to each other. The planetary gear mechanism 20B and the sun gear S2 are coupled to form a second coupling element 22. Torque TM1 generated by the first motor 2 is input to the first coupling element 21, and torque TM2 generated by the second motor 3 is input to the second coupling element 22. The carrier C1 of the first planetary gear mechanism 20A and the carrier C2 of the second planetary gear mechanism 20B are connected to the left and right drive wheels 4L and 4R, respectively, and outputs are taken out.

  In the example of FIG. 5A, the second coupling element 22 is configured to include a hollow shaft extending along the axis of the gear device 8, and the first coupling element 21 is inserted through the hollow shaft. Has been. The first coupling element 21 includes a solid shaft extending along the axis of the gear device 8, and the first coupling element 21 and the second coupling element 22 are arranged coaxially. The first coupling element 21, which is a solid shaft, has one end (the left end in the drawing) serving as the rotation shaft of the sun gear S1, and the other end (the right end in the drawing) penetrating the sun gear S2. 20A and 20B are connected. In addition, as for the 2nd coupling element 22 which is a hollow shaft, one end (right end in a figure) is a rotating shaft of the sun gear S2.

  In the example of FIG. 5B, the first coupling element 21 includes a hollow shaft extending along the axis of the gear device 8, and the second coupling element 22 is inserted through the hollow shaft. Has been. The second coupling element 22 includes a solid shaft that extends along the axis of the gear device 8, and the first coupling element 21 and the second coupling element 22 are arranged coaxially. However, in the example of FIG. 5B, one end (the right end in the figure) of the second coupling element 22 that is a solid shaft is the rotational axis of the sun gear S2, but the other end (the left end in the figure) is the sun gear S1. It is provided without penetrating.

  In the example of FIGS. 5A and 5B, only the two shafts of the first coupling element 21 and the second coupling element 22 are provided between the first planetary gear mechanism 20A and the second planetary gear mechanism 20B. Passing through. That is, between the first planetary gear mechanism 20A and the second planetary gear mechanism 20B, there is a double structure of only the first coupling element 21 and the second coupling element 22, and the two planetary gear mechanisms 20A, 20B. In between, these two shafts are supported by bearings (not shown).

  On the other hand, in the example of FIG. 5C, the first coupling element 21 and the second coupling element 22 are both disposed at positions radially outward from the shaft center of the gear device 8, and both are hollow shafts. It is comprised including.

  Here, the driving torque transmitted by the gear device 8 will be described with reference to a velocity diagram shown in FIG. Since the gear device 8 is configured by combining two identical single pinion planetary gear mechanisms 20A and 20B, it can be represented by two velocity diagrams as shown in FIG. Here, for easy understanding, the two speed diagrams are shifted up and down, the speed diagram of the first planetary gear mechanism 20A is shown on the upper side, and the speed diagram of the second planetary gear mechanism 20B is shown on the lower side.

  Further, in the speed diagram of the first planetary gear mechanism 20A and the speed diagram of the second planetary gear mechanism 20B, the sun gear S and the ring gear R are arranged opposite to each other (become left-right symmetry). That is, in FIG. 7, the ring gear R2 of the second planetary gear mechanism 20B is arranged under the sun gear S1 of the first planetary gear mechanism 20A, and the second planetary gear mechanism 20B is under the ring gear R1 of the first planetary gear mechanism 20A. A sun gear S2 is arranged.

  In the gear device 8, the elements located at both ends of the two velocity diagrams shown in FIG. 7 are joined to each other as shown by a broken line in the figure to form a first coupling element 21 and a second coupling element 22. The Then, torques TM1 and TM2 output from the first motor 2 and the second motor 3 are input to the first coupling element 21 and the second coupling element 22, respectively. On the other hand, drive torques TL and TR transmitted to the left and right drive wheels 4L and 4R from the carriers C1 and C2 positioned in the middle on the speed diagram are output.

Also by the gear device 8 configured in this way, a torque difference (input torque difference) ΔT _IN (= TM2−TM1) is given to the drive torques TM1 and TM2 generated by the first motor 2 and the second motor 3. A drive torque difference ΔT _OUT (= TL−TR) can be generated between the drive torque TL transmitted to the left drive wheel 4L and the drive torque TR transmitted to the right drive wheel 4R. That is, according to the gear device 8, the relationship of the following formula (9) is obtained. The coefficient β is a torque difference amplification factor.
ΔT _OUT = β × ΔT _IN (9)

  The torque difference amplification factor β of the gear device 8 according to the present embodiment will be described. Here, since the two single pinion planetary gear mechanisms 20A and 20B use gear elements having the same number of teeth, the distance between the ring gear R1 and the carrier C1 and the distance between the ring gear R2 and the carrier C2 are equal. Is a. Further, the distance between the sun gear S1 and the carrier C1 and the distance between the sun gear S2 and the carrier C2 are also equal, which is b. That is, FIG. 7 is obtained by replacing the positions of C1 and R1 and the positions of C2 and R2 with respect to FIG. 3 described in the first embodiment.

When the torques TM1 and TM2 of the first motor 2 and the second motor 3 are input to the first coupling element 21 and the second coupling element 22 at the left and right ends, respectively, and the driving torques TL and TR are taken out from the carriers C1 and C2, Expressions similar to the above expressions (2) to (6) are derived. In the case of a single pinion planetary gear mechanism, the length a is the reciprocal (1 / Z _R ) of the number of teeth Z _R of the ring gear R, and the length b is the reciprocal of the number of teeth Z _S of the sun gear S (1 / Z _S ). Therefore, the above equation (9) can be rewritten as the following equation (10).

  That is, the torque difference amplification factor β is expressed by the following equation (11).

Also in the single-pinion planetary gear mechanism as described above, approximately the ratio between the number of teeth Z _R of the number of teeth Z _S and the ring gear R of the sun gear S 1: for 2 is set to the torque difference amplification factor from equation (11) β is a value around 3.

[2-2. effect]
Therefore, according to the left and right wheel drive device 1 'according to the present embodiment, only the two shafts of the first coupling element 21 and the second coupling element 22 pass between the two planetary gear mechanisms 20A and 20B. That is, a double structure of the first coupling element 21 and the second coupling element 22. Thereby, rigidity and accuracy can be ensured between the two planetary gear mechanisms 20A and 20B without complicating the structure for supporting these two shafts. Further, the structure of the gear unit 8 can be simplified as compared with the case where a planetary gear mechanism of a continuous pinion type or Ravigneaux type is used.

Further, when different torques TM1 and TM2 are generated by the two motors 2 and 3, and the input torque difference ΔT _IN is given, the input torque difference ΔT _IN is amplified in the gear unit 8, and the driving torque larger than the input torque difference ΔT _IN is obtained. A difference ΔT _OUT can be obtained. That is, even when the input torque difference ΔT _IN is small, the gear device 8 can amplify the input torque difference ΔT _IN with a predetermined torque difference amplification factor β and is transmitted to the left driving wheel 4L and the right driving wheel 4R. A driving torque difference ΔT _OUT larger than the input torque difference ΔT _IN can be given to the driving torques TL and TR. Therefore, the cost can be reduced while obtaining a relatively large torque difference amplification factor β.

  In the left and right wheel drive device 1 ', the gear device 8 is configured by combining two single pinion planetary gear mechanisms 20A and 20B. Therefore, the structure is simpler than that of the first embodiment. And the cost can be further reduced.

  Also in the left and right wheel drive device 1 ′, as shown in FIGS. 5A and 5B, the first coupling element 21 and the second coupling element 22 are arranged coaxially and one is a solid shaft. And the other includes a hollow shaft through which a solid shaft is inserted. As a result, the shaft passing between the two planetary gear mechanisms 20A and 20B can have a double structure, the shaft support structure can be simplified, and the radial dimension of the gear device 8 can be reduced. It can be downsized.

  At this time, as shown in FIG. 5A, one end of the solid shaft is a rotating shaft of one sun gear and the other end passes through the other sun gear, and the two planetary gear mechanisms 20A are provided. , 20B are connected, the rigidity can be ensured with a simple configuration, and the structural reliability can be increased. Further, since the gear device 8 can be reduced in weight, the weight of the entire left and right wheel drive measure 1 'can be reduced.

Also in the left and right wheel drive apparatus 1 'described above, since the two electric motors 2 and 3 are used as drive sources, the input torque difference ΔT _IN can be easily generated.

[3. Others]
Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention.
For example, in each of the above embodiments, the combination of two identical planetary gear mechanisms 10A and 10B, 20A and 20B is illustrated, but the two planetary gear mechanisms may not be the same, for example, the required strength or The number of teeth of the two planetary gear mechanisms may be slightly different from each other because of the layout. The ratio of the number of teeth Z _R of the number of teeth Z _S and the ring gear R of the sun gear S 1: 2 is not limited to the front and rear.

Moreover, although the two drive sources are the electric motors 2 and 3 and are the motors of the same standard having the same maximum output, the two drive sources are not limited to this.
Moreover, although the layout example of right-and-left wheel drive device 1 and 1 'was shown to Fig.4 (a), (b) and Fig.5 (a)-(c), you may mount in a vehicle by arrangement other than these. . Further, as shown in FIG. 5 (c), one of the first coupling element 11 and the second coupling element 12 is constituted by a solid shaft and the other is constituted by a hollow shaft, and they are not arranged coaxially. May be.
The vehicle on which the left and right wheel drive devices 1 and 1 ′ are mounted is not limited to an electric vehicle or a hybrid electric vehicle, and may be, for example, a fuel cell vehicle using the first motor 2 and the second motor 3 as drive sources. .

1, 1 'Left and right wheel drive device 2 First motor (one drive source)
3 Second motor (the other drive source)
4L, 4R Left and right drive wheels 5,8 Gear unit 10A, 10B, 20A, 20B Planetary gear mechanism 11, 21 First coupling element 12, 22 Second coupling element S1 Sun gear (one first rotating body)
S2 Sun gear (the other first rotating body)
C1 carrier (one third rotating body, one second rotating body)
C2 carrier (the other third rotating body, the other second rotating body)
R1 ring gear (one second rotating body, one third rotating body)
R2 ring gear (the other second rotating body, the other third rotating body)
P1, P2 pinion gear
TM1 Torque of the first motor
TM2 Second motor torque ΔT _IN Input torque difference
TL Driving torque of left driving wheel
TR Drive torque of right drive wheel ΔT _OUT Drive torque difference α, β Torque difference gain
Number of teeth of Z _S sun gear
Number of teeth of Z _R ring gear

Claims (6)

A planetary gear mechanism having three elements and two degrees of freedom interposed between two drive sources mounted on a vehicle and independently controllable, left and right drive wheels, and the two drive sources and the left and right drive wheels A left and right wheel drive device comprising:
Each of the planetary gear mechanisms is provided with a sun gear as a first rotating body for input, a second rotating body for output provided coaxially with the sun gear, and provided with the sun gear, A third rotating body that rotates in a direction opposite to the sun gear when the rotating body is fixed,
The gear device includes a first coupling element in which one sun gear and the other third rotating body are coupled, and a second coupling element in which one third rotating body and the other sun gear are coupled. Have
One of the drive sources is connected to the first coupling element and the other drive source is connected to the second coupling element;
One of the driving wheels is connected to one of the second rotating bodies, and the other of the driving wheels is connected to the other of the second rotating bodies. 2. The left and right wheels according to claim 1, wherein the gear device is configured by combining two double pinion planetary gear mechanisms in which the second rotating body is a ring gear and the third rotating body is a carrier. Drive device. 2. The left and right wheels according to claim 1, wherein the gear device is configured by combining two single pinion planetary gear mechanisms in which the second rotating body is a carrier and the third rotating body is a ring gear. Drive device. The gear device is configured so that the first coupling element and the second coupling element are arranged coaxially, and one includes a solid shaft and the other includes a hollow shaft through which the solid shaft is inserted. The left and right wheel drive device according to any one of claims 1 to 3, wherein a shaft passing between the two planetary gear mechanisms has a double structure. The solid shaft is provided such that one end is a rotating shaft of one sun gear and the other end passes through the center of the other sun gear, and connects the two planetary gear mechanisms. 4. The left and right wheel drive device according to 4. The left and right wheel drive device according to any one of claims 1 to 5, wherein each of the two drive sources is an electric motor.

Images