JP2008215572A - Extensible actuator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To surely lock a female screw member fixed to the inside of the output rod of an extensible actuator without requiring a special lock means. <P>SOLUTION: Even if a lock nut 97 for fixing the female screw member 96 inside the output rod 33 is loosened, a bolt 103 for fixing the part to be detected 104 of a stroke sensor 102 to the output rod 33 extends through the output rod 33 and is engaged with the locking hole 96a of the female screw member 96. Therefore, the female member 96 is surely prevented from falling off the inside of the output rod 33. Also, since the bolt 103 fixing the part to be detected 104 is utilized for preventing the female screw member from falling off, there is no need of installing a special lock means. As a result, the increase of the number of components can be suppressed. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  According to the present invention, a male screw member connected to a motor and rotating and a female screw member fixed by fixing means inside an output rod are screwed together, and the male screw member is rotated together with the female screw member by rotating the male screw member by the motor. The present invention relates to a telescopic actuator that drives an output rod forward and backward.

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 such a feed screw mechanism, the male screw member is often made of iron, and the female screw member is often made of bronze or a non-ferrous alloy. Since the output rod of the feed screw mechanism is required to have sufficient strength, the output rod cannot be formed integrally with a female screw member made of bronze or a non-ferrous alloy, and iron or aluminum alloy is used to ensure strength. It is necessary to house the female screw member inside the hollow output rod configured as described above and fix it integrally by a fixing means such as a lock nut.

  In such a case, if the lock nut is loosened, the female screw member may be displaced with respect to the output rod, or the female screw member may fall off from the output rod. However, there is a problem that the number of parts increases when a special retaining means is provided.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to reliably prevent the female screw member fixed inside the output rod of the telescopic actuator without requiring any special retaining means.

  In order to achieve the above object, according to the invention described in claim 1, a male screw member connected to a motor and rotating, and a female screw member fixed by fixing means inside the output rod are screwed together, In a telescopic actuator that drives the output rod to move forward and backward together with the female screw member by rotating the male screw member with the motor, a detected portion for detecting a stroke position of the output rod is fixed with a bolt, A telescopic actuator is proposed in which the bolt penetrates the output rod and engages the female screw member, thereby preventing the female screw member from being pulled out of the output rod.

  The lock nut 97 of the embodiment corresponds to the fixing means of the present invention.

  According to the configuration of the first aspect, even when the fixing means for fixing the female screw member to the inner peripheral surface of the output rod is loosened, the bolt for fixing the detected portion to the output rod passes through the output rod and passes through the female screw. Since it engages with the member, it is possible to reliably prevent the female screw member from falling out of the output rod. In addition, since the bolt for fixing the detected portion is used to prevent the female screw member from falling off, it is not necessary to provide a special retaining preventing means, and the increase in the number of parts can be suppressed.

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

  1 to 8 show an embodiment of the present invention. FIG. 1 is a perspective view of a suspension device for a left rear wheel, FIG. 2 is a view in the direction of the arrow 2 in FIG. 1, and FIG. 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. FIG. 8 is a sectional view taken along line 8-8 in FIG.

  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 that time, the outer elastic bushes 79 and 79 and the inner elastic bush 80 made of an elastic body exhibit an automatic alignment function that absorbs a slight axial shift between the second carrier 70 and the input flange 74, and It can absorb a sudden change in torque and enable smooth power transmission.

  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 provided on the outer peripheral surface of the output rod 33 with a bolt 103. And a sensor main body 106 that houses a detection unit 105 such as a coil that magnetically detects the position of the detection unit 104. 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.

  By the way, the left and right toe control actuators 14 and 14 have a mirror-symmetric structure with respect to the center plane of the vehicle body, and the left and right first housings 31 and 31, left and right second housings 32 and 32, and left and right output rods 33. 33, the left and right male screw members 95, 95, the left and right female screw members 96, 96, etc. are mirror-symmetric members that are incompatible. Therefore, if the right output rod 33 is misassembled into the left second housing 32, or the left output rod 33 is misassembled into the right second housing 32, the function may not function normally.

  As is apparent from FIG. 8, the detected part 104 fixed to the detected part holder 114 positioned by the pin 113 on the upper surface of the output rod 33 and fixed by the bolt 103 is perpendicular to the axis L of the output rod 33. It is eccentric with respect to the plane P by a distance d in one direction. For example, in the toe control actuator 14 on the left side of the vehicle body, the detected portion 104 rotates counterclockwise (front side of the vehicle body) with respect to the vertical plane P passing through the axis L of the output rod 33 when viewed from the outside to the inside of the vehicle body. In the toe control actuator 14 on the right side of the vehicle body, the detected portion 104 is clockwise (front side of the vehicle body) with respect to the vertical plane P passing through the axis L of the output rod 33 when viewed from the outside of the vehicle body to the inside. Eccentric to the position rotated.

  The tip of the bolt 103 that fixes the detected portion holder 114 to the output rod 33 is engaged with a locking hole 96 a formed in the female screw member 96 through the output rod 33.

  According to the present embodiment, even if the right output rod 33 (shown by a chain line) is misassembled with the second housing 32 on the left side in FIG. Since it cannot be assembled by interference with the opening 32b of the housing 32, it is possible to reliably prevent the occurrence of misassembly.

  Although the output rod 33 is restricted from rotating around the axis L by the rubber bush joint 21 connected to the knuckle 11, only the elastic deformation of the rubber bush joint 21 can rotate. When the output rod 33 rotates, the detected portion 104 may come into contact with the opening 32b of the second housing 32 and be damaged. However, the stoppers 33c and 33c protruding from the outer periphery of the output rod 33 are provided with the opening of the second housing 32. By making it face 32b, damage to the detected portion 104 can be prevented.

  If the output rod 33 rotates around the axis L, if the upper surface of the detected portion 104 is a flat surface, the distance from the detecting portion 105 changes, and the detection accuracy of the stroke sensor 102 may decrease. There is. However, in the present embodiment, since the upper surface of the detected portion 104 facing the detecting portion 105 is formed as an arc surface centering on the axis L of the output rod 33, the detected portion is detected even if the output rod 33 rotates. The distance between the upper surface of the unit 104 and the detection unit 105 is kept constant, and a decrease in detection accuracy of the stroke sensor 102 is minimized.

  Further, even when the lock nut 97 for fixing the female screw member 96 inside the output rod 33 is loosened, the tip of the bolt 103 for fixing the detected portion holder 114 provided with the detected portion 104 to the output rod 33 is the female screw. Since the engaging hole 96a of the member 96 is engaged, it is possible to reliably prevent the female screw member 96 from being displaced with respect to the output rod 33 or falling off from the output rod 33. In addition, since the bolt 103 for fixing the detected portion holder 114 is used for preventing the female screw member 96 from falling off, it is not necessary to provide a special retaining member, and an increase in the number of parts can be suppressed.

  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.

  In the embodiment, the lock nut 97 is used as a fixing means for fixing the female screw member 96 to the output rod 33. However, any fixing means other than the lock nut 97 can be adopted.

Perspective view of left rear wheel suspension device 2 direction view of FIG. 3-3 enlarged sectional view of FIG. 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. 8-8 sectional view of FIG.

Explanation of symbols

33 Output rod 36 Motor 95 Male thread member 96 Female thread member 97 Lock nut (fixing means) 103 Bolt 104 Detected part

Claims (1)

A male screw member (95) connected to the motor (36) for rotation and a female screw member (96) fixed by fixing means (97) inside the output rod (33) are screwed together, and the motor (36) In the telescopic actuator for driving the output rod (33) together with the female screw member (96) by rotating the male screw member (95),
A detected part (104) for detecting the stroke position is fixed to the output rod (33) with a bolt (103), and the bolt (103) penetrates the output rod (33) and The telescopic actuator, wherein the female screw member (96) is retained from the output rod (33) by engaging with the female screw member (96).

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