JP2008164015A5 - - Google Patents

Description

Telescopic actuator

  The present invention relates to a telescopic actuator that relatively rotates a male screw member and a female screw member that are screwed to each other with a motor and outputs a relative displacement in the axial direction of the male screw member and the female screw member as a thrust force.

By controlling expansion and contraction of the upper link and lower link of the suspension system of the vehicle with an actuator to suppress changes in the camber angle and the ground tread due to the bump and rebound of the wheel, the steering stability performance is improved with a motor. The one constituted by a feed screw mechanism provided with a male screw member and a female screw member that rotate relative to each other is known from Patent Document 1 below.
Japanese Examined Patent Publication No. 6-47388

  By the way, in this type of actuator using a feed screw mechanism, since there is a minute backlash between the male screw member and the female screw member that rotate relative to each other, the male screw member is caused by a vibration load or a large load that is reversely transmitted from the output side. In addition, the female screw member slips and rotates relatively, and the actuator may expand and contract unintentionally. In order to prevent this, it is only necessary to generate a holding torque that restricts the relative rotation of the male screw member and the female screw member in the motor. However, this causes a new problem that the power consumption of the motor increases. .

  The present invention has been made in view of the above-described circumstances, and an object thereof is to mechanically restrict expansion and contraction of a telescopic actuator using a feed screw mechanism due to external force.

  In order to achieve the above object, according to the first aspect of the present invention, the male screw member and the female screw member that are screwed to each other are relatively rotated by a motor, and the axial displacement of the male screw member and the female screw member is achieved. An expansion / contraction actuator is provided, which includes an elastic body that biases one of the male screw member and the female screw member in the axial direction toward the other.

  According to the invention described in claim 2, in addition to the structure of claim 1, the female screw member is constituted by a plurality of elements divided in the axial direction, and each element is preloaded by the elastic body. A telescopic actuator is proposed, which is biased in directions away from each other.

  According to the invention described in claim 3, in addition to the configuration of claim 1 or claim 2, the elastic body is in a position to transmit a thrust force generated by relative rotation of the male screw member and the female screw member. A telescopic actuator is proposed, which is arranged and has a non-linear load characteristic with respect to the displacement of the elastic body.

  According to the invention described in claim 4, in addition to the configuration of claim 3, the elastic body has a displacement change rate at a small load and a large load with respect to a displacement change rate at a medium load. A telescopic actuator characterized by a small is proposed.

According to the invention described in claim 5, the male screw member and the female screw member that are screwed to each other are relatively rotated by a motor, and the axial displacement of the male screw member and the female screw member is output as a thrust force. In the actuator, there is proposed a telescopic actuator characterized by including an elastic body that urges the male screw member in the axial direction.

  In addition, the coil spring 101, the rubber bush 111, and the disc spring 112 of embodiment correspond to the elastic body of this invention.

  According to the configuration of the first aspect, when the male screw member and the female screw member that are screwed together are relatively rotated by the motor, the axial relative displacement of the male screw member and the female screw member can be output as a thrust force. If a vibrational external force or a large external force is input, the male screw member and female screw member may rotate relative to each other due to slipping, and the telescopic actuator may expand and contract unintentionally. By urging in the axial direction, it is possible to generate a frictional force between the male screw member and the female screw member to suppress the relative rotation and prevent the unintentional expansion and contraction from occurring.

  According to the second aspect of the present invention, since the plurality of elements obtained by dividing the female screw member in the axial direction are biased in a direction away from each other by the preload of the elastic body, between each element of the female screw member and the male screw member A frictional force can be generated. Moreover, since the elements of the female screw member do not rotate relative to each other, a means for preventing twisting of the elastic body is not required, and the structure is simplified.

  According to the third aspect of the present invention, the elastic body arranged at a position for transmitting the thrust force generated by the relative rotation of the male screw member and the female screw member has a characteristic that the load changes nonlinearly with respect to the displacement. In addition to suppressing unintentional relative rotation by generating a frictional force between the male screw member and the female screw member, the expansion amount of the telescopic actuator with respect to the motor rotation angle can be increased without special control of the motor rotation angle. Or decrease.

  According to the fourth aspect of the present invention, the non-linear characteristic of the elastic body is set so that the displacement change rate when the load is small and large is smaller than the displacement change rate when the load is medium. It is difficult to displace the elastic body at the time of a small load immediately after the operation of the expansion / contraction actuator, so that the response of expansion / contraction can be improved. The expansion / contraction speed can be reduced by increasing the load.

According to the configuration of the fifth aspect, when the male screw member and the female screw member screwed to each other are relatively rotated by the motor, the axial relative displacement of the male screw member and the female screw member can be output as a thrust force. When a vibrational external force or a large external force is input, the male screw member and female screw member may rotate relative to each other due to slipping, and the expansion actuator may perform unintended expansion / contraction, but the elastic member biases the male screw member in the axial direction. Thus, a frictional force can be generated between the male screw member and the female screw member to suppress the relative rotation, thereby preventing the unintended expansion and contraction.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

  1 to 7 show a first embodiment of the present invention. FIG. 1 is a perspective view of a left rear wheel suspension device, FIG. 2 is a view in the direction of the arrow 2 in FIG. 1, and FIG. 4 is an enlarged view of part 4 of FIG. 3, FIG. 5 is an enlarged view of part 5 of FIG. 3, FIG. 6 is an exploded perspective view of the speed reducer and coupling, and FIG. 7 is 7-7 of FIG. It is a line expanded sectional view.

  As shown in FIGS. 1 and 2, a double wishbone type rear suspension S for a four-wheel steering vehicle includes a knuckle 11 that rotatably supports a rear wheel W, and an upper that connects the knuckle 11 to a vehicle body so as to be movable up and down. The arm 12 and the lower arm 13, a toe control actuator 14 for connecting the knuckle 11 and the vehicle body to control the toe angle of the rear wheel W, a damper 15 with a suspension spring for buffering the vertical movement of the rear wheel W, and the like.

  The distal ends of the upper arm 12 and the lower arm 13 whose base ends are connected to the vehicle body by rubber bush joints 16 and 17, respectively, are connected to the upper and lower portions of the knuckle 11 via ball joints 18 and 19, respectively. The toe control actuator 14 has a proximal end connected to the vehicle body via a rubber bush joint 20 and a distal end connected to the rear portion of the knuckle 11 via a rubber bush joint 21. The lower end of the suspension spring-equipped damper 15 whose upper end is fixed to the vehicle body (upper wall 22 of the suspension tower) is connected to the upper portion of the knuckle 11 via the rubber bush joint 23.

  When the toe control actuator 14 is driven to extend, the rear portion of the knuckle 11 is pushed outward in the vehicle width direction, the toe angle of the rear wheel W changes in the toe-in direction, and when the toe control actuator 14 is driven to contract, the rear portion of the knuckle 11 is Pulled inward in the width direction, the toe angle of the rear wheel W changes in the toe-out direction. Therefore, in addition to normal steering of the front wheels by operating the steering wheel, by controlling the toe angle of the rear wheel W according to the vehicle speed and the steering angle of the steering wheel, the straight running stability performance and turning performance of the vehicle can be improved. it can.

  Next, the structure of the toe control actuator 14 will be described in detail with reference to FIGS.

  As shown in FIGS. 3 and 4, the toe control actuator 14 includes a first housing 31 integrally provided with a rubber bush joint 20 connected to the vehicle body side, and a rubber bush joint 21 connected to the knuckle 11 side. And a second housing 32 that supports the integrally provided output rod 33 so that the output rod 33 can extend and contract. The opposing portions of the first and second housings 31 and 32 are in a state where they are inlay-fitted through a seal member 34. The coupling flanges 31a and 32a are integrated by fastening with a plurality of bolts 35. A motor 36 with a brush as a driving source is housed in the first housing 31, and a planetary gear type reduction gear 37, an elastic coupling 38, and a trapezoidal screw are used in the second housing 32. The feed screw mechanism 39 is housed.

  As described above, the first housing 31 that houses the motor 36 and the second housing 32 that houses the speed reducer 37, the coupling 38, and the feed screw mechanism 39 are sub-assembled in advance, and they are combined to form a toe. Since the control actuator 14 is configured, the design of the toe control actuator 14 as a whole is changed when it is desired to change the motor 36 to one having a large output or a small output, or to change the operating characteristics of the speed reducer 37 or the feed screw mechanism 39. Accordingly, it is possible to cope with the problem by exchanging only the subassembly on the first housing 31 side or the subassembly on the second housing 32 side, thereby improving the versatility for various models and reducing the cost.

  The outer shell of the motor 36 includes a yoke 40 having a flange 40a and formed in a cup shape, and a bearing holder 42 fastened to the flange 40a of the yoke 40 with a plurality of bolts 41. Bolts 41 for fastening the yoke 40 and the bearing holder 42 are screwed into the end face of the first housing 31, and the motor 36 is fixed to the first housing 31 using the bolts 41.

  The rotor 44 disposed in the annular stator 43 supported on the inner peripheral surface of the yoke 40 is rotatably supported at one end of a rotating shaft 45 by a ball bearing 46 provided at the bottom of the yoke 40 and at the other end. A ball bearing 47 provided on the holder 42 is rotatably supported. A brush 49 that is in sliding contact with a commutator 48 provided on the outer periphery of the rotating shaft 45 is supported on the inner surface of the bearing holder 42. The conducting wire 50 extending from the brush 49 is drawn to the outside through a grommet 51 provided in the first housing 31.

  The yoke 40, which is a strong component that houses the stator 43 and the rotor 44, constitutes the outer shell of the motor 36, and the yoke 40 is fixed to the first housing 31, so that the load input from the rear wheel W to the toe control actuator 14 Can be received by the first housing 31 so as not to act on the motor 36, and the durability and reliability of the motor 36 can be improved. In addition, since a clearance α is formed between the outer peripheral surface of the yoke 40 of the motor 36 and the inner peripheral surface of the first housing 31, the operation sound of the motor 36 leaks outside the first housing 31 due to the clearance α. As well as suppressing the external force, the external force acting on the first housing 31 can be more reliably prevented from being transmitted to the motor 36.

  In addition, the motor 36 is fixed to the first housing 31 by using bolts 41 that integrally fasten the yoke 40 and the bearing holder 42 of the motor 36. Therefore, the motor 36 is connected to the first housing by a bolt different from the bolts 41. Compared to the case of fixing to 31, not only the number of bolts can be reduced, but also the space for arranging the other bolts can be reduced, and the toe control actuator 14 can be downsized.

  As shown in FIGS. 4 and 5, the speed reducer 37 is configured by coupling a first planetary gear mechanism 61 and a second planetary gear mechanism 62 in two stages. The first planetary gear mechanism 61 includes a ring gear 63 that is fitted and fixed to the opening of the second housing 32, a first sun gear 64 that is directly formed at the tip of the rotating shaft 45 of the motor 36, and a disk-like shape. The first carrier 65 and the first pinion pins 66, which are cantilevered by press-fitting into the first carrier 65, are rotatably supported via ball bearings 67, and simultaneously mesh with the ring gear 63 and the first sun gear 64. And four first pinions 68. The first planetary gear mechanism 61 decelerates and transmits the rotation of the first sun gear 64 that is an input member to the first carrier 65 that is an output member.

  The second planetary gear mechanism 62 of the speed reducer 37 includes a ring gear 63 common to the first planetary gear mechanism 61, a second sun gear 69 fixed to the center of the first carrier 65, a disc-shaped second carrier 70, and the like. Four second pinion pins 71, which are cantilevered by press-fitting into the second carrier 70, are rotatably supported via slide bushes 72, and simultaneously mesh with the ring gear 63 and the second sun gear 69. 2 pinions 73... The second planetary gear mechanism 62 decelerates and transmits the rotation of the second sun gear 69 that is an input member to the second carrier 70 that is an output member.

  Thus, by connecting the first and second planetary gear mechanisms 61 and 62 in series, a large reduction ratio can be obtained, and the reduction gear 37 can be downsized. Further, since the sun gear 64 of the first planetary gear mechanism 61 is formed directly on the rotating shaft 45 without being fixed to the rotating shaft 45 of the motor 36, the parts are compared with the case where the first sun gear 64 separate from the rotating shaft 45 is used. Not only can the number of points be reduced, but also the diameter of the first sun gear 64 can be minimized and the reduction ratio of the first planetary gear mechanism 61 can be set large.

  The second carrier 70 that is an output member of the speed reducer 37 is connected to an input flange 74 that is an input member of the feed screw mechanism 39 via a coupling 38. The generally disc-shaped input flange 74 is rotatably supported with its outer peripheral portion sandwiched between a pair of thrust bearings 75 and 76. That is, an annular lock nut 78 is fastened to the inner peripheral surface of the second housing 32 so as to sandwich the spacer collar 77, and one thrust bearing 75 applies a thrust load between the second housing 32 and the input flange 74. The other thrust bearing 76 is arranged to support the thrust load between the lock nut 78 and the input flange 74.

  4, 6, and 7, the coupling 38 includes two outer elastic bushes 79 and 79 made of, for example, polyacetal, and one inner elastic bush 80 made of, for example, silicon rubber. .., 80a... And 8 grooves 79b... 80b. On the other hand, four claws 70a, 74a,... Protrude from the opposing surfaces of the second carrier 70 and the input flange 74 so as to face each other in the axial direction at equal intervals.

  The outer elastic bushes 79, 79 and the inner elastic bush 80 are overlapped so that the phases of the protrusions 79a, 80a,... Are aligned, and the second carrier 70 is placed in every other four of the eight grooves 79b, 80b,. Are engaged, and the remaining four of the eight grooves 79b, 80b are engaged with the four claws 74a of the input flange 74.

  Accordingly, the torque of the second carrier 70 is transmitted from the claws 70a of the second carrier 70 to the outer elastic bushes 79, 79 and the inner elastic bush 80 via the projections 79a, 80a, and the claws 74a of the input flange 74. And transmitted to the input flange 74. At this time, the outer elastic bushes 79 and 79 and the inner elastic bush 80 made of an elastic body absorb a minute axial deviation between the second carrier 70 and the input flange 74 and absorb a sudden change in torque. Smooth power transmission can be achieved.

  As is clear from FIG. 5, the first slide bearing 91 is fixed to the inner peripheral surface of the axially intermediate portion of the second housing 32, and the end member 93 that is screwed to the axial end portion of the first housing 32 is inside. A second slide bearing 92 is fixed to the peripheral surface, and the output rod 33 is slidably supported by the first and second slide bearings 91 and 92. The feed screw mechanism 39 that converts the rotational motion of the input flange 74 into the thrust motion of the output rod 33 includes a male screw member 95 that passes through the center of the input flange 74 and is fastened by a nut 94 (see FIG. 4), and the male screw member. 95 and a female screw member 96 fitted to the inner peripheral surface of the hollow output rod 33 and fixed by a lock nut 97.

  As described above, since the output rod 33 is supported by the second housing 32 via a plurality of (two in the embodiment) slide bearings 91 and 92, the radial load applied to the output rod 33 is applied to the second housing 32. Thus, the feed screw mechanism 39 can be prevented from being distorted.

  A coil spring 101 is contracted between a spring seat 99 supported at the tip of the male screw member 95 via a thrust bearing 98 and a spring seat 100 provided at the tip of the output rod 33. The elastic force of the coil spring 101 urges the female screw member 96 fixed to the output rod 33 and the male screw member 95 screwed into the female screw member 96 in opposite directions, and the male screw member 95 and the female screw member. It functions to eliminate backlash between 96 threads.

  Thereby, the screw threads of the male screw member 95 and the female screw member 96 are always brought into close contact with each other to generate a frictional force, and when a vibrational load is input to the female screw member 96 from the rear wheel W side or from the rear wheel W side, the female screw When a large load is input to the member 96, it is possible to prevent the male screw member 95 from rotating freely and changing the toe angle of the rear wheel W, and toe angle control accuracy is improved. As a result, it is not necessary to flow an electric current through the motor 36 to suppress unintended rotation of the male screw member 95, and the power consumption of the motor 36 is reduced.

  A stroke sensor 102 provided in the second housing 32 for detecting the stroke position of the output rod 33 and feeding it back to the control device when the toe control actuator 14 is expanded and contracted is attached to the outer peripheral surface of the output rod 33 with a bolt 103. A detected portion 104 made of a fixed permanent magnet and a sensor body 106 that houses a detecting portion 105 such as a coil for magnetically detecting the position of the detected portion 104 are provided. In the second housing 32, an opening 32 b extending in the axial direction is formed so as to prevent the detected portion 104 from interfering with the movement of the output rod 33.

  An annular stopper 107 is provided on the outer periphery of the output rod 33, and this stopper 107 abuts against the contact surface 93b of the end member 93 when the output rod 33 moves to the limit position in the extending direction. By providing the stopper 107, it is possible to reliably prevent the output rod 33 from falling off the second housing 32 even if the motor 36 runs away due to some abnormality. Further, since the stopper 107 is disposed using the dead space sandwiched between the first and second slide bearings 91 and 92, the space can be reduced. In addition, since the second slide bearing 92 is provided on the end member 93 that can be separated from the second housing 32, the output rod 33 including the stopper 107 is not obstructed by the second slide bearing 92. It can be attached and detached.

  In order to prevent water and dust from entering the gap between the second housing 32 and the output rod 33, the boot 108 is inserted into the annular step 32 c formed in the second housing 32 and the annular groove 33 a formed in the output rod 33. The both ends are fitted and fixed by bands 109 and 110, respectively. At this time, the annular step 32c of the second housing 32 and the flange 93a of the end member 93 cooperate to form an annular groove, so that one end of the boot 108 fixed by the band 109 is prevented from falling off. Can do. Further, since the boot 108 is prevented from falling off by using the flange 93a of the end member 93, it is only necessary to provide the annular step portion 32c without providing the annular groove in the second housing 32, compared with the case where the annular groove is formed. Processing becomes easy. In addition, since the width of the annular step 32c having only one shoulder is smaller than that of the annular groove having two shoulders, the axial dimension of the second housing 32 can be reduced accordingly.

  When the output rod 33 extends, the volume of the internal space of the first and second housings 31 and 32 increases, and conversely, when the output rod 33 contracts, the volume of the internal space of the first and second housings 31 and 32 decreases. The pressure in the internal space may fluctuate and hinder the smooth operation of the toe control actuator 14. However, since the internal space of the hollow output rod 33 and the internal space of the boot 108 communicate with each other through the vent hole 33 b formed in the output rod 33, the pressure fluctuation is reduced by the deformation of the boot 108. The toe control actuator 14 can be smoothly operated.

  Next, a second embodiment of the present invention will be described with reference to FIG.

  In the first embodiment described above, the compressed coil spring 101 is disposed between the male screw member 95 and the output rod 33 (female screw member 96). However, in the second embodiment, the female screw member 96 is provided. The element is divided into two elements 96A and 96B, and a cylindrical rubber bush 111 is fixed between them by baking. The female screw member 96 is screwed into the male screw member 95 in a state where a preload in the compression direction is applied to the rubber bush 111, and the elastic force of the rubber bush 111 causes the two elements 96A and 96B to elastically move away from each other. The screw teeth are energized and are pressed against the screw teeth of the male screw member 95.

  According to the second embodiment, in addition to the effects of the first embodiment described above, the rubber bush 111 is interposed between the two elements 96A and 96B of the female screw member 96 that do not rotate relative to each other. There is no need to dispose a special member such as the thrust bearing 98 (see FIG. 5) of the first embodiment between the rubber bush 111 and the two elements 96A and 96B. Since the rubber bushing 111 can be arranged within the range of dimensions, it is not necessary to secure a special arrangement space for the rubber bushing 111.

  Next, a third embodiment of the present invention will be described based on FIG. 9 and FIG.

  In the third embodiment, a plurality of overlapping disc springs 112 are arranged between the output rod 33 and the female screw member 96 which are transmission paths for the thrust force generated by the feed screw mechanism 39. These disc springs 112 are the same as those in the first and second embodiments in that the female screw member 96 is urged toward the male screw member 95 and the screw threads are brought into close contact with each other. In the embodiment, the following additional effects can be achieved by the non-linear characteristics of the disc springs 112.

  The graph of FIG. 10 shows a non-linear relationship between the displacement and load of the disc springs 112. The rate of change of the displacement is small in the region A where the load is small and the region C where the load is large, and the rate of change of the displacement is large in the region B where the load is medium. That is, in the region A with a small load and the region C with a large load, the disc springs 112 are hardly crushed even if the load increases.

  Accordingly, when the output rod 33 starts to expand from the contracted state, that is, when the reaction load from the rear wheel W is still small, the disc spring 112 is not easily crushed. 14 actuation responsiveness can be improved. Further, when the output rod 33 approaches the extension limit, that is, when the reaction force load from the rear wheel W becomes large, the disc spring 112 is not easily crushed. Therefore, the reaction force load increases the load of the motor 36. The expansion / contraction speed of the output rod 33 can be reduced.

  Thus, by arranging the disc springs 112 having non-linear characteristics in the thrust force transmission path of the toe control actuator 14, the toe with respect to the rotation angle of the motor 36 is not controlled without specially controlling the rotation angle of the motor 35. The amount of expansion / contraction of the control actuator 14 can be increased or decreased.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and various design changes can be made without departing from the present invention described in the claims. Is possible.

  For example, the use of the telescopic actuator of the present invention is not limited to the toe control actuator 14 described in the embodiment, and can be applied to any use. However, if the telescopic actuator is applied to the toe control actuator 14, the unsprung load of the suspension S can be reduced due to its small and lightweight characteristics.

  Further, the elastic body of the present invention is not limited to the coil spring 101, the rubber bush 111, and the disc spring 112, which are described in the embodiment, and the mounting positions of the elastic bodies of the male screw member 95 and the female screw member 96 are mutually different. Any position can be used as long as it can generate an elastic force to be brought into close contact with.

  In the embodiment, a trapezoidal screw is used for the feed screw mechanism 39, but other types of screws such as a ball screw can be used.

The perspective view of the suspension device of the left rear wheel concerning a 1st embodiment 2 direction view of FIG. Vertical section of toe control actuator 4 enlarged view of FIG. 5 enlarged view of FIG. Exploded perspective view of reducer and coupling FIG. 7 is an enlarged sectional view taken along line 7-7. The figure corresponding to the said FIG. 5 based on 2nd Embodiment. The figure corresponding to the said FIG. 5 based on 3rd Embodiment. Graph showing disc spring displacement and load characteristics

Explanation of symbols

36 Motor 95 Male thread member 96 Female thread member 96A Element 96B Element 101 Coil spring (elastic body)
111 Rubber bush (elastic body)
112 Disc spring (elastic body)

Claims (5)

The male screw member (95) and the female screw member (96) that are screwed together are relatively rotated by a motor (36), and the axial relative displacement of the male screw member (95) and the female screw member (96) is output as a thrust force. In a telescopic actuator that
A telescopic actuator comprising an elastic body (101, 111, 112) for urging one of the male screw member (95) and the female screw member (96) in the axial direction toward the other.   The female screw member (96) is composed of a plurality of elements (96A, 96B) divided in the axial direction, and the elements (96A, 96B) are separated from each other by the preload of the elastic body (111). The telescopic actuator according to claim 1, wherein the telescopic actuator is biased.   The elastic body (112) is disposed at a position to transmit a thrust force generated by relative rotation of the male screw member (95) and the female screw member (96), and a load characteristic with respect to the displacement of the elastic body (112). The telescopic actuator according to claim 1, wherein is a non-linear type.   The expansion / contraction actuator according to claim 3, wherein the elastic body (112) has a smaller displacement change rate at a small load and a large load than a displacement change rate at an intermediate load. The male screw member (95) and the female screw member (96) that are screwed together are relatively rotated by the motor (36), and the axial relative displacement of the male screw member (95) and the female screw member (96) is output as a thrust force. In a telescopic actuator that
A telescopic actuator comprising an elastic body (101, 111, 112) for urging the male screw member (95) in the axial direction.