JP4951568B2 - Power transmission mechanism - Google Patents

Description

  The present invention relates to a power transmission mechanism that converts rotational force into direct power to transmit power.

As a power transmission mechanism, an actuator is known in which power is transmitted from a rotation output shaft through a coupling and the rotational force is converted into direct power.
This type of actuator includes a motor as a drive source, a speed reducer that reduces the rotational speed of the motor, and a feed screw (screw portion) that transmits the rotational force of the motor decelerated by the speed reducer via a coupling. ) And a nut portion that meshes with the feed screw and converts the rotational force into direct power.

As such a power transmission mechanism (actuator), what is used for an independent rear-wheel steering apparatus is known (for example, refer patent document 1).
JP 2007-290417 A

In the power transmission mechanism of Patent Document 1, the rotational force of a servo motor (motor) is transmitted to an inner cylinder in which a screw part is formed, and is transmitted to an outer cylinder in which a nut part meshed with a male screw is formed. The rotational force was converted into the direct power of the outer cylinder and the power was transmitted.
Furthermore, an independent rear wheel steering device is configured by connecting a tie rod that changes the toe angle of the rear wheel to the tip of the outer cylinder of the power transmission mechanism.

Such power transmission mechanism (actuator) is generally between the rotation output shaft and the screw portion is accepted side of the motor is the sender, the coupling to prevent misalignment of the axis In detail, in detail, a feed side power transmission unit is provided on the rotation output shaft side of the motor, a receiving side power transmission unit is provided on the screw side, and a coupling is interposed between these transmission units. It was.

However, in such a power transmission mechanism, the receiving-side power transmission portion forms a pawl portion that receives the coupling by cutting at the end of the forged feed screw. For this reason, two different processes, forging and cutting, are necessary, and the machining process is complicated.
Furthermore, in the power transmission mechanism described above, as an example, there is a problem in that the yield is poor because the pawl is left at the end of the feed screw and all parts other than the pawl are scraped off.

  It is an object of the present invention to provide a power transmission mechanism that can simplify a machining process and has a high yield.

The invention according to claim 1 is a power transmission mechanism that converts rotational force into direct power by a nut portion and a screw portion, receives power from the rotational power output member via the coupling at the screw portion, In the power transmission mechanism for transmitting the cup portion, a cup portion that accommodates the coupling is formed at the end portion of the screw portion by forging , the cup portion is provided with a claw portion that locks the coupling, and the coupling includes the cup portion. A cylindrical portion that abuts the bottom portion and abuts on the pawl portion, and an engagement piece that extends radially from the cylindrical portion and engages the pawl portion, and the cup portion is cut only at a site where the cylindrical portion abuts. It is characterized by being processed .

The invention according to claim 2 is characterized in that the portion with which the cylindrical portion of the cup portion abuts is the center portion of the bottom portion of the cup portion and the tip portion of the claw portion .
In the invention according to claim 3, the cylindrical portion is partially extended in the axial direction from the engagement piece, the center portion of the bottom portion of the cup portion is concave, and the center portion of the bottom portion of the cup portion is Further, it is characterized in that it abuts the extended cylindrical portion in the circumferential direction.

In the invention according to claim 4 , the coupling is configured by superposing at least two members, the other side member is inserted into the shaft portion of the one side member, and the other side member is inserted into the one side member. It is characterized by being engaged.

In the invention according to claim 5 , the cylindrical portion has both ends in the axial direction extending in the axial direction from the engaging piece, and is formed only by the shaft portion of the one side member of the coupling, and more than the other side member. It is long in the axial direction .

In the invention according to claim 1, the power transmission mechanism converts the rotational force into the direct power by the nut portion and the screw portion, receives power from the rotational power output member through the coupling at the screw portion, Power is transmitted to the part.
Since the cup part that accommodates the coupling at the end of the thread part is formed by forging, the thread part and the cup part can be formed only by forging. Thereby, the manufacturing process can be simplified. In addition, since only the forging-only manufacturing process is performed, the product yield can be improved.

Further , the cup portion includes a claw portion for locking the coupling. The coupling includes a cylindrical portion that abuts on the bottom portion of the cup portion and abuts on the claw portion, and a claw portion that extends radially from the cylindrical portion. And the cup portion is cut only on the portion where the cylindrical portion abuts, so that the cutting portion can be reduced.
Furthermore, since the cup portion is cut only at the portion where the cylindrical portion abuts, the holding accuracy of the coupling can be improved and the rattling of the coupling can be reduced.
In the invention according to claim 2, the portion where the cylindrical portion of the cup portion abuts is the center portion of the bottom portion of the cup portion and the tip portion of the claw portion.
In the invention according to claim 3, the cylindrical portion is partially extended in the axial direction from the engagement piece, the center portion of the bottom portion of the cup portion is concave, and the center portion of the bottom portion of the cup portion is , Abuts the extended cylindrical portion in the circumferential direction.

In the invention according to claim 4 , the coupling is configured by overlapping at least two members, the other side member is inserted into the shaft portion of the one side member, and the other side member is inserted into the one side member. Since it is engaged, the accuracy in the axial direction of the coupling can be improved.

In the invention according to claim 5 , the cylindrical portion has both ends in the axial direction extending in the axial direction from the engagement piece, and is formed only by the shaft portion of the one side member of the coupling, and more than the other side member. Long in the axial direction.

The best mode for carrying out the present invention will be described below with reference to the accompanying drawings. The drawings are viewed in the direction of the reference numerals.
FIG. 1 is a principle diagram of an independent rear wheel steering device on which a power transmission device according to the present invention is mounted.
The independent rear wheel steering device 10 includes a rear wheel 12 provided at a lower rear side of the vehicle body 11 so that a toe angle can be adjusted, a suspension (suspension device) 13 that supports the rear wheel 12 in a swingable manner, a vehicle body 11 side and a rear wheel. An actuator (power transmission mechanism ) 30 is provided between the wheel 12 side and controls the toe angle of the rear wheel 12.

  The suspension 13 is, for example, a double wishbon type suspension device, and includes a lower arm 16 that swingably extends from below the vehicle body 11, and an upper arm 17 that swings and extends above the lower arm 16 and from the vehicle body 11. These arms 16, 17 are rotatably provided, knuckle 18 that supports the rear wheel 12, the upper end is supported by the vehicle body 11, the lower end is attached to the lower arm 16, and an impact applied to the vehicle body 11 from the rear wheel 12 is applied. It consists of a shock absorber unit 19 that softens.

One end of the actuator 30 is swingably supported on the vehicle body 11 side, and the other end is swingably attached to the knuckle 18. As will be described later, the torque is converted into direct power to convert the toe angle of the rear wheel 12. Is to control.
The operation principle of the independent rear wheel steering apparatus 10 will be described with reference to the next figure.

2 (a) to 2 (c) are operation explanatory views of the independent rear wheel steering device on which the power transmission device according to the present invention is mounted.
In (a), the independent rear wheel steering device 10 in an initial state in which the rear wheel 12 is positioned in parallel to the center of the vehicle body is shown.

In (b), the rear wheel 12 can be driven inward of the vehicle body 11 by extending the actuator 30 as shown by the arrow a1, and can be controlled to a toe-in state.
In (c), by retracting the actuator 30 as indicated by an arrow a2, the rear wheel 12 can be driven to the outside of the vehicle body 11 and controlled to a toe-out state.
Hereinafter, details of the actuator 30 will be described.

FIG. 3 is a front sectional view of the power transmission device according to the present invention, and FIG. 4 is an exploded perspective view of main components of the power transmission device according to the present invention.
As shown in FIGS. 3 and 4, the actuator (power transmission mechanism) 30 is a member that converts rotational force into direct power, is divided into two parts, and is provided on one side housing (vehicle side) that is attached to the vehicle body 11 side. Member) 31, a second housing (rear wheel side member) 32 that is divided into two parts and is attached to the rear wheel 12 side, and an inner peripheral surface 33 of the one side housing 31 as a drive source that generates rotational force. Motor 34, an output shaft (rotation output shaft) 35 of the motor 34, a reduction gear 36 configured to be disposed on the one-side housing 31 to reduce the rotational speed of the motor 34, and a final speed reducer 36. A feed screw 38 that is connected to a stage (rotary power output member) 75 via a coupling 37 and is configured in the other housing 32 to convert the rotational force into direct power, and this feed , A nut portion 39 that is attached to the other side housing 32 and converts from rotational force to direct power, one side housing (vehicle body side member) 31, and the other side housing (rear wheel side member) 32. And a dust boot 42 that covers the space between them with a rotation seal member 41 as a main component.

The dust boot 42 is made of elastomer as a material that is resistant to stepping stones and has excellent weather resistance.
Elastomer is a synthetic polymer material, especially a material having elasticity and flexibility like rubber at around room temperature.

  The feed screw 38 and the nut portion 39 are conversion members that convert a rotational force into a direct power. The nut portion 39 is locked to the other housing 32 by a set screw 47.

The one side housing 31 includes a vehicle body side connecting portion 48 connected to the vehicle body 11 side, and the motor 34 and the speed reducer 36 are provided in the one side housing 31.
The other housing 32 includes a rear wheel side connecting portion 49 connected to the rear wheel 12 side, and the other housing 32 is provided with a feed screw 38 and a nut portion 39.

  That is, the actuator 30 is aligned with the one side housing 31 provided with the motor 34 and the speed reducer 36 with the other side housing 32 provided with the feed screw 38 and the nut portion 39 via the coupling 37. The dust boots 42 are put between the one side housing 31 and the other side housing 32.

  The motor 34 includes a rotor 51, a stator 52 provided around the rotor 51, and a motor case 53 that covers the rotor 51 and the stator 52, and an output shaft 35 is provided at the center of the rotor 51.

The motor case 53 includes a block portion 54 that projects one end of the output shaft 35 toward the speed reducer 36, and a storage portion 55 that is attached to the block portion 54 and fixes the stator 52 and rotatably supports the rotor 51. .
Further, the motor case 53 is held on the one side housing 31 by a ring gear 62 which is a component of the speed reducer 36, with the outer peripheral surface 56 (end surface of the block portion 54) of the motor case 53 sandwiched between the one side housing 31.

  As shown in FIG. 4, the speed reducer 36 includes a sun gear 61 fitted to the output shaft 35 of the motor 34, a ring gear 62 disposed concentrically with the sun gear 61, and the sun gear 61 and the ring gear 62. The first gear assembly 64 meshes with the first gear assembly 64 and the second gear assembly 65 meshes with the first gear assembly 64.

  A female screw 66 is formed on the inner peripheral surface 33 of the one side housing 31, and a male screw 68 is formed on the outer peripheral portion 67 of the ring gear 62, and is screwed onto the inner peripheral surface 33 of the one side housing 31.

  The first gear assembly 64 includes a disk-shaped first base 71, a plurality of planetary gears 72 that are rotatably attached to the first base 71 and meshed with the sun gear 61 and the ring gear 62, And a pinion 73 provided at the center of one base 71 and on the opposing surfaces of the plurality of planetary gears 72.

  The second gear assembly 65 includes a disk-shaped second base 75 and a plurality of gears rotatably attached to the second base 75 and meshed with the pinion 73 of the first gear assembly 64. 76.

The second base portion 75 is a final stage of the speed reducer 36 and is a member corresponding to a rotational power output member. The second base portion 75 is provided concentrically with the second base portion 75 and on the opposing surfaces of the plurality of gears 76. A plurality of protrusions 77 that engage with the ring 37 and a support shaft 78 that rotatably supports the plurality of gears 76 are provided.
In the figure, 79 is an oil seal interposed between the one side housing 31 and the other side housing 32.

FIG. 5 is a perspective view of the threaded portion and coupling of the power transmission device according to the present invention, and FIG. 6 is a perspective view of the components of the coupling and reduction gear of the power transmission device according to the present invention.
As shown in FIG. 5, the feed screw 38 includes a screw portion 81 that is screwed into the nut portion 39, a cup portion 82 that houses the coupling 37 on the coupling 37 side of the screw portion 81, A bottom portion 83 that is in sliding contact with the cylindrical portion 91 and a plurality of claw portions 84 that mesh with the coupling 37 are provided.

  As shown in FIGS. 5 and 6, the coupling 37 is a member in which three members of one side member 87, an intermediate member 88, and the other side member 89 are laminated. It extends radially from the cylindrical portion 91 and is interposed between the plurality of claw portions 84 of the feed screw 38 and the plurality of protrusions 77 of the speed reducer 36, and the shaft center on the feed screw 38 side and the shaft center on the motor 34 side. The engaging piece 92 transmits the rotational force on the motor 34 side to the feed screw 38 side while absorbing the deviation.

7A to 7D are coupling comparison studies of the power transmission device according to the present invention, and a detailed structure of the coupling 37 is shown.
In (a), (b), the coupling 37 of an Example is shown, (a) is a plane of the coupling 37, (b) is the bb sectional view taken on the line a.

  As described above, the coupling 37 is a member in which three members of the one side member 87, the intermediate member 88, and the other side member 89 are laminated, and the one side member 87 includes the cylindrical portion described above. 91 is formed, and a fitting portion 94 for fitting the other side member 89 is formed. The other side member 89 has a fitting claw 95 for fitting the one side member 87 and a penetrating through the cylindrical portion 91. A hole 93 is formed, and a hole 96 penetrating the fitting claw 95 is formed in the intermediate member 88. The cylindrical portion 91 is also a shaft portion through which the intermediate member 88 and the other side member 89 pass.

  In the laminated structure of the coupling 37, the intermediate member 88 and the other side member 89 are inserted into the cylindrical portion 91 of the one side member 87, and the intermediate member 88 is sandwiched between the one side member 87 and the other side member 89. The fitting claw 95 of the other side member 89 is fitted to the fitting portion 94 of the side member 87.

  That is, the coupling 37 is configured by overlapping at least two members, the other side member 89 is inserted into the shaft portion (cylindrical portion) 91 of the one side member 87, and the other side is inserted into the one side member 87. Since the member 89 is engaged, the accuracy of the coupling 37 in the axial direction can be improved.

In (c) and (d), the coupling 200 of a comparative example is shown, (c) is a plane of the coupling 200, and (d) is a sectional view taken along the line dd of c.
The coupling 200 is a member in which three members, one side member 201, an intermediate member 202, and the other side member 203 are laminated. In the figure, reference numeral 204 denotes an engagement piece that meshes between two members (for example, the output shaft side of the motor and the feed screw side).

  In the laminated structure of the coupling 200, the intermediate member 202 is sandwiched between the one side member 201 and the other side member 203 and is fitted from both the one side member 201 and the other side member 203. FIG. Since there is no cylindrical part (shaft part) 91 shown in the embodiment of a), the radial accuracy of the coupling 200 is inferior.

  Further, since the coupling 200 is structured to be fitted from both the one side member 201 and the other side member 203, variations in the axial dimensions of the one side member 201, the intermediate member 202, and the other side member 203 are likely to occur.

  As shown in (b) and (d), when the axial dimensions Lb and Ld of the couplings 37 and 200 are compared, the dimension Lb is determined with an accuracy of one part, but the dimension Ld is a dimension of three parts. Accumulation of accuracy. Therefore, the dimensional accuracy of the coupling 37 in the axial direction is superior to the dimensional accuracy of the coupling 200 in the axial direction.

FIGS. 8A to 8D are first comparative study diagrams of the cup portion formed on the feed screw of the power transmission device according to the present invention.
(A), (b) shows the feed screw 38 of the embodiment, (a) is a perspective view of the feed screw 38, and (b) is a plan view of the feed screw 38. In (c) and (d), a feed screw 210 of a comparative example is shown, (c) is a perspective view of the feed screw 210, and (d) is a plan view of the feed screw 210.

  As shown in (a) and (b), the feed screw 38 is formed by forging a cup portion (concave portion) 82 that accommodates the coupling 37 at the end portion of the screw portion 81. That is, by forming a plurality of claw portions 84 meshing with the coupling 37 in the cup portion (concave portion) 82, the cup portion 82 including the screw portion 81 and the claw portion 84 can be easily formed only by forging.

As shown in (c) and (d), the feed screw 210 forms a plurality of fitting claws (convex portions) 213 that fit into the coupling 216 at the end of the screw portion 211. The nail | claw (convex part) 213 can generally be formed by forging or cutting.
In the feed screw 210, when the fitting claw 213 is formed by forging, the height of the fitting claw 213 cannot be made too high. Moreover, when forming by cutting, cost rises.

  That is, since the feed screw 38 is formed by forging a cup portion (recessed portion) 82 that accommodates the coupling 37 at the end portion of the screw portion 81, the cup portion 82 including the screw portion 81 and the pawl portion 84 can only be forged. Can be molded. Thereby, the manufacturing process can be simplified. In addition, since only the forging-only manufacturing process is performed, the product yield can be improved.

  FIGS. 9A to 9D are second comparative study diagrams of the cup portion formed on the feed screw of the power transmission device according to the present invention. In FIGS. 9A and 9B, the cup portion 82 of the embodiment is shown. And (c) and (d) show the relationship between the cup part 222 and the coupling 226 of the comparative example.

  As shown in (a) and (b), in the feed screw 38, the cup portion 82 is formed in a concave shape, the claw portion 84 is formed on the inner periphery of the cup portion 82, and the coupling 37 is connected to the cup portion 82. A cylindrical portion 91 is formed in sliding contact with the bottom 83 of the cylinder. The cup portion 82 is cut only at a portion where the cylindrical portion 91 abuts. Here, the abutting part (abutting part) corresponds to the center part 83 a of the bottom part 83 and the tip parts 84 a of the plurality of claw parts 84.

As shown in (c) and (d), the feed screw 220 has a concave cup portion 222 formed at the end of a screw portion (not shown), and a plurality of fitting claws on the inner periphery of the cup portion 222. 223 is formed. Further, the coupling 226 has a structure in which the whole is in sliding contact with the bottom portion 225 of the cup portion 222.
Accordingly, even when the bottom portion 225 of the cup portion 222 is cut, the entire bottom portion 225 needs to be cut. In the feed screw 220, the fitting claw 223 hinders the cutting process, and the cutting process is also difficult.

That is, in the power transmission mechanism 30 of the embodiment, the cutting process is performed only on the part that contacts the cylindrical part 91 of the cup part 82, so that the cutting part can be reduced.
Further, since the cup portion 82 is cut only at a portion where the cylindrical portion 91 abuts, the holding accuracy of the coupling 37 can be improved and the rattling of the coupling 37 can be reduced.

  As shown in FIGS. 1 and 2, the power transmission mechanism 30 is applied to an independent rear wheel steering device 10 that steers the left and right rear wheels 12 independently, so that the left and right rear wheels are mounted on a finished vehicle. 12 movement variations can be minimized. As a result, it is possible to simplify the toe angle adjustment of the left and right rear wheels 12 during assembly of the complete vehicle.

  In FIG. 1, the independent rear wheel steering device 10 that steers the left rear wheel 12 is shown, but the independent rear wheel steering device that steers the right rear wheel 12 is the same as the independent rear wheel steering device 10. It is configured with respect to the center of the vehicle body.

  In the power transmission mechanism 30 according to the present invention, as shown in FIG. 7, the cylindrical portion 91 is formed on the one side member 87 of the coupling 37. However, the present invention is not limited to this, and the one side member of the coupling is not limited thereto. The intermediate member 88 or the other side member may be formed.

  The power transmission mechanism according to the present invention is suitable for use in passenger cars such as sedans and wagons.

It is a principle figure of the independent rear-wheel steering device by which the power transmission device which concerns on this invention is mounted. It is operation | movement explanatory drawing of the independent rear-wheel steering apparatus by which the power transmission device which concerns on this invention is mounted. It is front sectional drawing of the power transmission device which concerns on this invention. It is a disassembled perspective view of the main components of the power transmission device according to the present invention. It is a perspective view of the screw part and coupling of the power transmission device concerning the present invention. It is a perspective view of the component of the coupling of a power transmission device and a reduction gear which concern on this invention. It is a coupling comparison examination figure of the power transmission device concerning the present invention. It is a 1st comparative examination figure of the cup part formed in the feed screw of the power transmission device concerning the present invention. It is the 2nd comparative examination figure of the cup part formed in the feed screw of the power transmission device concerning the present invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Independent rear-wheel steering apparatus, 30 ... Power transmission mechanism (actuator), 37 ... Coupling, 39 ... Nut part, 75 ... Rotary power output member (the last stage or 2nd base part of a reduction gear), 81 ... Screw part , 83 ... bottom part, 84 ... claw part, 87 ... one side member, 89 ... other side member, 91 ... shaft part (cylindrical part), 92 ... engagement piece.

Claims (5)

In the power transmission mechanism that converts the rotational force into direct power by the nut part and the screw part, receives power from the rotational power output member through the coupling at the screw part, and transmits power to the nut part.
Forming a cup part for accommodating the coupling at an end of the screw part by forging ;
The cup portion includes a claw portion that locks the coupling, and the coupling is in contact with a bottom portion of the cup portion and is in contact with the claw portion, and is radially extended from the cylindrical portion. An engagement piece that engages with the claw portion,
The power transmission mechanism according to claim 1, wherein the cup portion is cut only at a portion where the cylindrical portion abuts . 2. The power transmission mechanism according to claim 1 , wherein the portion of the cup portion with which the cylindrical portion abuts is a center portion of a bottom portion of the cup portion and a tip portion of the claw portion . A part of the cylindrical part extends in the axial direction from the engagement piece, and a central part of the bottom part of the cup part has a concave shape,
The power transmission mechanism according to claim 2 , wherein a center portion of a bottom portion of the cup portion abuts on the extended cylindrical portion in a circumferential direction . The coupling is configured by overlapping at least two members, and the other side member is inserted into the shaft portion of the one side member, and the other side member is engaged with the one side member. The power transmission mechanism according to claim 1, wherein: Both ends of the cylindrical portion in the axial direction extend in the axial direction from the engagement piece, and are formed only by the shaft portion of one side member of the coupling, and are longer in the axial direction than the other side member. The power transmission mechanism according to claim 4.

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