JP2012189172A - Linear actuator device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control degradation of the durability of a rolling screw mechanism by controlling generation of the radial load.SOLUTION: A linear actuator device includes: a rolling screw mechanism 100 having a screw shaft 1 and a nut member 2; a driven member 3 which is driven to be directly operated by the rolling screw mechanism while its moving direction is restricted on the line by a guide member; and a connection mechanism 200 for connecting the rolling screw mechanism to the driven member. The connection mechanism includes: a first parallel four-link mechanism 71 having the node L5 which cannot be relatively rotated around the center axis of a screw shaft with respect to the nut member; and a second parallel four-link mechanism 72 having the node L4 which cannot be relatively rotated around its directly operated direction with respect to the driven member. The node L20 arranged opposite to the node L5 in the first parallel link mechanism and the node L20 arranged opposite to the node L4 in the second parallel link mechanism are fixed on an intermediate member 20.

Description

  The present invention relates to a linear actuator device including a coupling mechanism that couples a rolling screw mechanism and a driven member.

  In recent years, as part of measures against environmental problems and global warming, there is an increasing tendency to use electric actuators as actuators for various devices in place of conventional hydraulic actuators. This is because when using electric actuators, the use of hydraulic oil required for hydraulic equipment is an environmental measure, and at the same time, power consumption can be reduced by improving the efficiency through electrification, and further power consumption using power regeneration is achieved. It is possible to reduce power, to convert the energy source from fuel of the internal combustion engine to electric power, to reduce the local environmental load at the actuator operation site, and to be able to effectively use energy in a wide area by using midnight power via a battery. Etc.

  As a rotation-linear motion conversion mechanism used in an electric linear actuator, a rolling screw mechanism represented by a ball screw is frequently used. This is because the frictional resistance is small and contributes to efficiency improvement. However, in the rolling screw mechanism, moment loads and radial loads (loads acting in the radial direction of the screw shaft) differing from the thrust generated in the axial direction of the screw shaft (driving force in the axial direction of the screw shaft (linear driving force)) ) May significantly reduce the service life, and the load mode must be considered. This is also clearly stated in the product description of rolling screws including ball screws.

  By the way, in some linear actuator devices using a rolling screw mechanism, a driven member that is linearly driven by a nut member does not move on the axis of the screw shaft (that is, a position away from the axis of the screw shaft). In some cases, the driven member is driven linearly). In this type of linear actuator device, in order to guide the linear movement of the driven member, a member (guide member) that supports the driven member so as to be substantially parallel movable with respect to the axis of the screw shaft is separately required. . In this case, the member that guides the linear movement direction of the nut member (that is, the screw shaft) is different from the member that guides the linear movement direction of the driven member (that is, the guide member). It is difficult to keep the direction and the linear motion direction of the driven member completely parallel. Therefore, the distance and direction between the nut member and the driven member change with the linear movement of the driven member, and depending on the connecting method of the nut member and the driven member, the compressive force or tensile force between them becomes a radial load. It acts between the nut member and the screw shaft. The original function of the linear actuator is to generate thrust (driving force in the axial direction of the screw shaft) and transmit this to the driven member. In the process, the necessity of applying a radial load to the rolling screw mechanism is Absent.

  In view of this point, as a technique for suppressing an adverse effect due to a radial load in the rolling screw mechanism, a nut member that is engaged with the screw shaft and is movable in the axial direction (substantially vertical direction) of the screw shaft, and a guide device are provided. An elevator car frame (driven member) that is movable in the vertical direction along the vertical beam (guide member) is connected via a translational joint, and a screw shaft is provided between the car frame and the screw shaft. Even if a radial displacement occurs, the joint can absorb the displacement (Japanese Patent Laid-Open No. 2000-344448).

JP 2000-344448 A

  However, in the above technique, since the radial displacement is absorbed by relatively sliding the members constituting the joint and in surface contact with each other, the frictional force generated in the joint when the load of the driven member is enormous. Is too large, which is not preferable from the viewpoint of durability and energy efficiency.

  Further, in order to convert the rotation of the screw shaft into the linear motion of the nut member, it is necessary to prevent the rotation of the nut member against the torque generated by the reaction force of the thrust and acting on the nut member. If this is done by preventing the nut member from moving in the circumferential direction at a position away from the axial center of the screw shaft, the radial load that forms the couple together with the circumferential force acting on the nut member will cause the nut member and the screw shaft to Will act between. Therefore, it is necessary to consider this point in order to prevent a radial load from acting on the rolling screw mechanism as much as possible.

  The objective of this invention is providing the linear actuator apparatus which can suppress generation | occurrence | production of a radial load and can suppress the durable fall of a rolling screw mechanism.

  In order to achieve the above object, the present invention provides a screw shaft having a spiral groove formed on the outer peripheral surface, and a rolling screw mechanism having a nut member that contacts the screw shaft via a rolling element that rolls on the spiral groove; A driven member whose movement direction is constrained linearly by a guide member and driven linearly by the rolling screw mechanism; and a connecting mechanism for connecting the rolling screw mechanism and the driven member; A four-joint first parallel link mechanism having one joint that is not rotatable relative to the nut member around the central axis of the screw shaft, and a one that is relatively non-rotatable around the linear motion direction relative to the driven member. A four-node second parallel link mechanism having a node; a node disposed opposite to one node which is not rotatable relative to the nut member in the first parallel link mechanism; and the second parallel link mechanism in the second parallel link mechanism Clause that is opposed to relative rotation of Section 1 with respect to the driving member is intended to comprise an intermediate member fixed.

  According to the present invention, since the generation of a radial load can be suppressed, the durability of the rolling screw mechanism can be improved.

The side view of the linear actuator apparatus which concerns on the 1st Embodiment of this invention. The top view of the linear actuator apparatus shown in FIG. The schematic diagram of the link mechanism formed in the linear actuator apparatus which concerns on the 1st Embodiment of this invention. The side view of the linear actuator apparatus which concerns on the 2nd Embodiment of this invention. FIG. 5 is a top view of the linear actuator device shown in FIG. 4. DD sectional drawing in FIG. The schematic diagram of the link mechanism formed in the linear actuator apparatus which concerns on the 2nd Embodiment of this invention. The side view of the lift apparatus of the forklift which concerns on the 3rd Embodiment of this invention. EE sectional drawing in FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a side view of the linear actuator device according to the first embodiment of the present invention, and includes a BB cross section in FIG. FIG. 2 is a top view of the linear actuator device shown in FIG. 1 and includes a cross section AA in FIG. The linear actuator device shown in these drawings includes a rolling screw mechanism 100, a driven member 3, a coupling mechanism 200, and an uneven load prevention mechanism 60.

  The rolling screw mechanism 100 includes a screw shaft 1 having a spiral groove formed on the outer peripheral surface, and a screw shaft 1 and a screw pair via a rolling element (not shown) such as a ball or a roller that rolls on the spiral groove of the screw shaft 1. The nut member 2 combined is provided. When the screw shaft 1 and the nut member 2 are rotated relatively around the axis of the screw shaft 1, the nut member 2 is relative to the screw shaft 1 in the axial direction of the screw shaft 1 (vertical direction in FIG. 1). And the thrust is generated in the axial direction of the screw shaft 1. In the present embodiment, the nut member 2 is configured to move linearly in the axial direction of the screw shaft 1 by rotating the screw shaft 1 by a drive source such as a motor.

  The driven member 3 is supported by a guide member (not shown) that supports the driven member 3 so as to be movable on a straight line substantially parallel to the axis of the screw shaft 1. It is linearly driven by the rolling screw mechanism 100 at a position away from it.

  The connecting mechanism 200 connects the rolling screw mechanism 100 and the driven member 3, and connects the nut member 2 and the driven member 3 in the present embodiment. The connecting mechanism 200 includes a thrust member 5, an intermediate plate 7, link members 9a and 9b, link members 13a and 13b, a link member 4, a link member (intermediate member) 20, shafts 10a and 10b, and a shaft. 14a, 14b, shafts 17a, 17b, thrust ball bearing 11, thrust ball bearing 15, thrust ball bearing 18, needle roller bearing 12, needle roller bearings 16a, 16b, and needle roller bearings 19a, 19b. I have.

  The thrust member 5 is connected to the nut member 2 via the uneven load prevention mechanism 60, and the upward thrust in FIG. 1 is transmitted from the nut member 2. The uneven load prevention mechanism 60 includes an intermediate plate 7 into which the screw shaft 1 is inserted and four half-moon shoes 6.

  On the surface (upper surface) on the thrust member 5 side of the intermediate plate 7, two half-moon shaped grooves for housing the half-moon shoes 6 are provided so as to face each other with the screw shaft 1 interposed therebetween. In the two grooves, a half-moon shoe 6 restrained at one point by a pin 8 attached to the thrust member 5 is accommodated, and the intermediate plate 7 is contacted by the contact portion between the two half-moon shoes 6 and the intermediate plate 7. Is formed. Further, two half-moon-shaped grooves in which the half-moon shoe 6 is stored are provided on the surface (lower surface) of the intermediate plate 7 on the nut member 3 side so as to face each other with the screw shaft 1 interposed therebetween. In the two grooves, a half-moon shoe 6 restrained at one point by a pin 8 attached to the nut member 2 is accommodated, and the intermediate plate 7 is connected by a contact portion between the two half-moon shoes 6 and the intermediate plate 7. Is formed. As described above, the two rocking shafts formed by the two pairs of meniscus shoes 6 disposed on the upper surface and the lower surface of the intermediate plate 7 are substantially orthogonal to each other when viewed from the axial direction of the screw shaft 1. Thereby, the uneven load prevention mechanism 60 exhibits the function of allowing the intersection of the two swing shafts to pass through the thrust generated by relatively rotating the screw shaft 1 and the nut member 2.

  The two link members 9a and 9b are connected to the thrust member 5 via shafts 10a and 10b, respectively, and are supported so as to be relatively rotatable with respect to the thrust member 5 about the shaft centers of the shafts 10a and 10b. Has been. That is, the link members 9a and 9b and the thrust member 5 are connected by a rotating pair. In the present embodiment, one ends of the shafts 10a and 10b are fixed to the link members 9a and 9b, respectively. The other ends of the shafts 10 a and 10 b are rotatably inserted into holes provided in the thrust member 5, whereby the shafts 10 a and 10 b are rotatably supported by the thrust member 5. Needle roller bearings 12 are incorporated around the shafts 10a and 10b (rotation support portions) on the thrust member 5 side. A thrust ball bearing 11 is incorporated in each of the thrust transmission portions located around the shafts 10 a and 10 b and between the link members 9 a and 9 b and the thrust member 5 in the axial direction of the screw shaft 1. ing. The two shafts 10a and 10b are arranged so that a line connecting two points appearing when the axes of the shafts 10a and 10b are viewed from the axial direction passes through the intersection of the two swing shafts in the uneven load prevention mechanism 60. ing.

  The two link members 13a and 13b are connected to the link members 9a and 9b via shafts 14a and 14b, respectively, and are relatively relative to the link members 9a and 9b with the shaft centers of the shafts 14a and 14b as the center. It is rotatably supported. That is, the link members 13a and 13b and the link members 9a and 9b are connected by a rotating pair. In this Embodiment, the convex part provided in link member 13a, 13b is engage | inserted by the recessed part provided in link member 9a, 9b, and the thrust of the nut member 2 is linked member 9a, via the said recessed part and convex part. 9b is transmitted to the link members 13a and 13b. A thrust ball bearing 15 is incorporated in the thrust transmission portion located between the concave portion and the convex portion in the axial direction of the shafts 14a and 14b. The link members 9a and 9b incorporate two needle roller bearings 16a and 16b at different positions in the axial direction of the shafts 14a and 14b, respectively, and support the shafts 14a and 14b in a rotatable manner. ing.

  The two link members 13a and 13b are connected to the link member 4 via shafts 17a and 17b, respectively, and can be rotated relative to the link member 4 about the shaft centers of the shafts 17a and 17b. It is supported by. That is, the link members 13a and 13b and the link member 4 are connected by a rotating pair. In this Embodiment, the convex part provided in link member 13a, 13b is engage | inserted by the recessed part provided in the link member 4, and the thrust of the nut member 2 is transmitted from the link member 13a, 13b via the said recessed part and convex part. It is transmitted to the link member 4. A thrust ball bearing 18 is incorporated in the thrust transmission portion located between the concave portion and the convex portion in the axial direction of the shafts 17a and 17b. The link member 4 incorporates two needle roller bearings 19a and 19b at different positions in the axial direction of the shafts 17a and 17b, respectively, and supports the shafts 17a and 17b in a rotatable manner. .

  The shaft 14 a and the shaft 14 b are connected by a link member 20, and the distance between the axes of the two shafts 14 a and 14 b is held constant by the link member 20. Specifically, the distance between the axes of the two shafts 14 a and 14 b is equal to the distance between the axes of the two shafts 10 a and 10 b inserted into the thrust member 5, and is further inserted into the link member 4. The distance between the shaft centers of the two shafts 17a and 17b is set to be equal.

  Further, the distance between the shaft centers of the shaft 14a and the shaft 9a is set to be equal to the distance between the shaft centers of the shaft 14b and the shaft 9b, and the distance between the shaft centers of the shaft 14a and the shaft 17a is set between the shaft 14b and the shaft 9a. It is set to be equal to the distance between the shaft centers of 17b.

  The link member 4 is fixed with a bolt or the like and is integrated with the driven member 3. Similarly to the driven member 3, the link member 4 is formed only on a line substantially parallel to the axis of the screw shaft 1 by a guide member (not shown). The moving direction is constrained to move.

  Next, a mechanism for reducing the radial load acting between the screw shaft 1 and the nut member 2 in the coupling mechanism 200 will be described with reference to FIG. FIG. 3 is a schematic diagram of a link mechanism formed in the linear actuator device according to the first embodiment of the present invention. In addition, the same code | symbol is attached | subjected to the same part as the previous figure, and description is abbreviate | omitted (the following figure is also the same).

  As shown in this figure, the linear actuator device configured as described above includes a node (link) L5 formed on the thrust member 5, nodes L9a and L9b formed on the link members 9a and 9b, and a link member. 20, a node L20 formed on the link member 13a, 13b, a node L13a formed on the link member 13b, a node L4 formed on the link member 4, a rotating pair J10a connecting the node L9a, L9b and the node L5, J10b, a rotation pair J14a that connects the nodes L9a, L20, and L13a, a rotation pair J14b that connects the nodes L9b, L20, and L13b, and a rotation pair that connects the nodes L13a, L13b, and the node L4. J17a and J17b are provided.

  Here, attention is paid to the link mechanism 71 formed by the four nodes of the node L5, the node L9a, the node L9b, and the node L20. As described above, since the distance between the axes of the two shafts 14a and 14b is equal to the distance between the axes of the two shafts 10a and 10b, the lengths of the nodes L5 and 20 are equal. Further, since the distance between the shaft centers of the shaft 14a and the shaft 9a is equal to the distance between the shaft centers of the shaft 14b and the shaft 9b, the lengths of the nodes L9a and L9b are equal. That is, in the link mechanism 71 formed in the four nodes, the two nodes (nodes L5 and L20, nodes L9a and L9b) arranged opposite to each other have the same length. Therefore, the link mechanism 71 formed by these four sections is a parallel link mechanism (hereinafter, the parallel link mechanism formed by these four sections may be referred to as a first parallel link mechanism 71).

  On the other hand, attention is paid to the four nodes of the node L4, the node L13a, the node L13b, and the node L20. As described above, since the distance between the axes of the two shafts 14a and 14b is equal to the distance between the axes of the two shafts 17a and 17b, the lengths of the nodes L4 and 20 are equal. Further, since the distance between the shaft centers of the shaft 14a and the shaft 17a is equal to the distance between the shaft centers of the shaft 14b and the shaft 17b, the lengths of the nodes L13a and L13b are equal. That is, in the link mechanism formed in the above four nodes, the two nodes (nodes L4 and L20, nodes L13a and L13b) arranged opposite to each other have the same length. Therefore, the link mechanism formed by these four sections is a parallel link mechanism (hereinafter, the parallel link mechanism formed by these four sections may be referred to as a second parallel link mechanism).

  Further, since the node L5 in the first parallel link mechanism 71 is formed on the thrust member 5 fixed to the nut member 2 via the uneven load preventing mechanism 60, the node L5 is not rotatable relative to the nut member 2. It has become. Further, in the first parallel link mechanism 71, the node L5 and the node L20 arranged opposite to the node L5 are always held in parallel, so that the node L20 translates with respect to the node L5 (the thrust member 5 and the nut member 2). Can rotate but cannot rotate relatively.

  On the other hand, the node L 4 in the second parallel link mechanism 72 is formed on the link member 4 fixed to the driven member 3, so that it is a node that cannot rotate relative to the driven member 3. Further, in the second parallel link mechanism 72, the node L4 and the node 20 disposed opposite to the node L4 are always held in parallel, so that the node 20 can translate with respect to the node L4 (driven member 3). Can not rotate relatively.

  Here, the node arranged opposite to the node L5 in the first link mechanism 71 and the node arranged opposite to the node L4 in the second link mechanism 72 are the same node fixed to the link member (intermediate member) 20. Since the relationship between the nodes L20 and L5 and the relationship between the nodes L20 and L4 described above are combined, the thrust member 5 is relatively movable with respect to the driven member 3 (link member 4). Cannot be rotated automatically. Further, since the thrust member 5 and the nut member 2 are constrained so as not to be able to rotate relative to each other via the unbalanced load preventing mechanism 60, the driven member 3 is relatively movable even if it can translate relative to the nut member 2. Will not be able to rotate. Therefore, the nut member 2 is prevented from rotating (spinning) around the screw shaft 1 by the coupling mechanism 200. At this time, the nut member 2 is prevented from rotating by a couple of forces acting via the two nodes L9a and L9b arranged opposite to each other in the first parallel link mechanism 71, so that the nut member 2 and the screw shaft 1 It is possible to avoid a radial load acting between them.

  Therefore, according to the present embodiment, since the generation of radial load can be suppressed, the durability of the rolling screw mechanism 100 can be improved.

  In the first parallel link mechanism 71, the rotating pair portions J10a and 14a positioned below FIG. 3 and the rotating pair portions J14a and J17a positioned below FIG. 3 in the second parallel link mechanism 72 are arranged on a straight line. (In this case, the rotation pair J10a, J14a positioned above FIG. 3 in the first parallel link mechanism 71 and the rotation pair J14b positioned above FIG. 3 in the second parallel link mechanism 72) J17b is also not arranged on a straight line). Also, this condition is that the node L9a located below the FIG. 3 in the first parallel link mechanism 71 and the node L13a located below the FIG. 3 in the second parallel link mechanism 71 form an angle other than 180 degrees. Thus, it can be said that it is preferable to form the link mechanisms 71 and 72 (at this time, the nodes L9b and L13b also form an angle other than 180 degrees).

  When the two link mechanisms 71 and 72 are formed in this way, the nut member 2 and the driven member 3 can translate in any direction in a two-dimensional region in a plane orthogonal to the axial direction of the screw shaft 1. it can. That is, two degrees of freedom can be given to the nut member 2 and the driven member 3. Thus, the axial direction of the screw shaft 1 (linear motion direction of the nut member 2) and the direction of the guide member (linear motion direction of the driven member 3) are not parallel, Accordingly, even when the distance and direction between the two and 3 change, a large compressive force or tensile force is not applied between the two and 3 by the connecting mechanism 200. Therefore, it can be avoided that a large radial load acts between the nut member 2 and the screw shaft 1. Therefore, according to the present embodiment configured as described above, the durability of the rolling screw mechanism 100 can be further improved.

  Further, in the linear actuator device configured as described above, the nodes transmitting the thrust from the rolling screw mechanism 100 in the first parallel link mechanism 71 and the second parallel link mechanism 72 are the nodes L9a, L9b, L13a, L13b. The nodes adjacent to these four nodes in the transmission direction of the thrust are nodes L5, L13a, L13b, and L4. Therefore, in the present embodiment, thrust ball bearings 11, 15, and 18 which are rolling bearings for thrust loads having a very small friction coefficient are installed between them. Specifically, the thrust ball bearings 11 are respectively installed in two thrust transmission portions formed between the node L5 and the nodes L9a and L9b, and are formed between the nodes L9a and L9b and the nodes L13a and L13b. The thrust ball bearings 15 are respectively installed in the two thrust transmission portions, and the thrust ball bearings 18 are respectively installed in the two thrust transmission portions formed between the nodes L13a, L13b and the node L4. As a result, the friction coefficient of the relative motion part can be greatly reduced, and the frictional resistance due to the thrust load when the distance and direction of the nut member 2 and the driven member 3 are changed by the coupling mechanism 200 having the two degrees of freedom is reduced. Therefore, it is possible to suppress a large radial load resulting from the action between the nut member 2 and the screw shaft 1.

  Furthermore, in the above-described embodiment, a load approximately half of the thrust acts on one thrust ball bearing 11, and the moment obtained by multiplying this by the distance between the shafts 10a, 10b and the shafts 14a, 14b gives the shaft 14a. , 14b acting on the rotation pair J14a, J14b, and a moment obtained by multiplying the load between the shafts 10a, 10b and the shafts 17a, 17b by a load almost half of the thrust is applied to the shafts 17a, 17b. Acting on the rotating pair J17a, J17b. Here, the nodes transmitting the thrust from the rolling screw mechanism 100 in the first parallel link mechanism 71 and the second parallel link mechanism 72 are the nodes L9a, L9b, L13a, and L13b as described above. Rotating pair portions with nodes adjacent to the nodes are rotating pair portions J10a, J10b, J14a, J14, J17a, and J17b. Then, from these six rotating pairs J10a, J10b, J14a, J14, J17a, J17b, the first parallel link mechanism 71 cannot rotate relative to the nut member 2, and the nodes L9a, L9b adjacent to the node L5 cannot be rotated. Needle roller bearings 16 and 19 which are rotational pairs are installed in the rotational pair portions (that is, rotational pair portions J14a, J14, J17a and J17b) excluding the rotational pair portions J10a and J10b which are rotational pair portions. Yes.

  More specifically, the rotation pair portions J14a and J14b with the shafts 14a and 14b as axes are provided with two rotation pairs via the needle roller bearings 16a and 16b, and the rotations with the shafts 17a and 17b as axes. The pair parts J17a and J17b are also provided with two rotary pairs through needle roller bearings 19a and 19b. Two rotation pairs in each of the rotation pair portions J14a, J14b, J17a, J17b are arranged at a predetermined interval in the axial direction of the screw shaft 1, and these rotation pairs are transmitted when transmitting the acting moment. It is possible to suppress the magnitude of the radial load generated at the same time. In addition, a rolling bearing for a radial load having a very small friction coefficient is incorporated. For this reason, the frictional resistance due to the radial load when the distance and direction of the nut member 2 and the driven member 3 change can be reduced by the coupling mechanism having the two degrees of freedom, and the large radial load resulting therefrom can be reduced. There is no effect between the member 2 and the screw shaft 1. In the present embodiment, four rotation pair portions J14a, excluding the two rotation pair portions J10a, J10b from the rotation pair portions of the node transmitting the thrust from the rolling screw mechanism 100 and the node adjacent to the node. Although needle roller bearings are installed for all of J14, J17a, and J17b, even if needle roller bearings are installed in at least one of these four rotating pairs J14a, J14, J17a, and J17b, they are caused by radial load. Needless to say, the effect of reducing the frictional resistance is exhibited.

  In the above-described embodiment, the first parallel link mechanism 71 has the two nodes L9a and L9b adjacent to the node L5 that cannot rotate relative to the nut member 2, and the second parallel link mechanism 72 has the driven member 3 connected to the driven member 3. On the other hand, the thrust from the rolling screw mechanism 100 is transmitted to the driven member 3 by the two nodes L13a and L13b adjacent to the node L4 that cannot be relatively rotated. When the thrust is transmitted in this way, the thrust can be transmitted in two paths from the nut member 2 to the driven member 3, and the bearing load in each path can be halved, so a particularly large thrust is generated. It is suitable for a linear actuator device. However, this configuration is not essential for the present invention, and thrust is transmitted to the driven member 3 by at least one of the two nodes L9a and L9b and at least one of the two nodes L13a and 13b. You may do it. One specific example is a linear actuator device according to a second embodiment described below.

  Next, a second embodiment of the present invention will be described. FIG. 4 is a side view of the linear actuator device according to the second embodiment of the present invention, and includes a CC cross section in FIG. FIG. 5 is a top view of the linear actuator device shown in FIG. 6 is a cross-sectional view taken along the line DD in FIG.

  The linear actuator device shown in these drawings includes a driven member 21 and a coupling mechanism 200A. The driven member 21 is a combination of the driven member 3 and the link member 4 in the first embodiment. The connecting mechanism 200 includes a thrust member 23, a link member 24, a link member 27, a link member (intermediate member) 22, a link member 30, a link member 33, a shaft 28, a shaft 29, and a shaft 26. The shaft 35, the shaft 32, the shaft 34, the thrust ball bearing 25, the thrust ball bearing 36, and the thrust ball bearing 31 are provided. Here, the link member 22 corresponds to the link member 20 in the first embodiment.

  The thrust member 23 is connected to the nut member 2 via the uneven load prevention mechanism 60, and thrust is transmitted from the nut member 2. Further, a link member 24 is connected to the thrust member 23 via a thrust ball bearing 25 as a rotating pair, and a link member 22 is connected to the link member 24 via a shaft 26 as a rotating pair. In addition, a link member 27 is connected to the thrust member 23 via a shaft 28 in a rotating pair, and a link member 22 is connected to the link member 27 via a shaft 29 in a rotating pair.

  The upper race and the spherical seat of the thrust ball bearing 25 are constrained by the link member 24 and the thrust member 23 so as not to move in the radial direction, whereby the thrust ball bearing 25 exhibits the function of a radial bearing. Further, the thrust ball bearing 25 is screwed so that its center is in the vicinity of the intersection point when the two swing shafts of the uneven load prevention mechanism 60 constituted by the half-moon shoe 6, the intermediate plate 7, the pin 8 and the like are viewed from above. It arrange | positions so that the axis | shaft 1 may be enclosed. The thrust member 23, the link member 24, the intermediate member 22 and the link member 27 are four-joint link mechanisms each having a node, and further, the length of the nodes arranged so as to be the first parallel link mechanism 71A. Each is equal.

  A link member 30 is connected to the driven member 21 through a thrust ball bearing 31 with a shaft 32 as an axis, and an intermediate member 22 is connected to the link member 30 via a shaft 26 as a rotation pair. Has been. Further, a link 33 member is connected to the driven member 21 through a shaft 34 in a rotational pair, and the intermediate member 22 is connected to the link member 33 through a shaft 35 in a rotational pair. The driven member 21, the link member 30, the intermediate member 22, and the link member 33 are four-node link mechanisms each having a node, and further, the nodes arranged correspondingly so that they become the second parallel link mechanism 72A. The lengths are the same.

  Further, the link member 24 and the link member 30 are connected by a rotating pair with a shaft 26 as an axis via a thrust ball bearing 36. As a result, the thrust transmitted from the nut member 2 to the thrust member 23 is first transmitted to the link member 24 via the thrust ball bearing 25, then transmitted to the link member 30 via the thrust ball bearing 36, and finally It is transmitted to the driven member 21 via the thrust ball bearing 31. That is, in the first embodiment, there are two thrust transmission paths, whereas in the present embodiment, there is only one thrust transmission path. Usually, since a large thrust load or a large radial load acts on the thrust transmission path, a rolling bearing for thrust load is used to reduce the frictional resistance and the radial load acting between the screw shaft 1 and the nut member 2. It is necessary to incorporate rolling bearings for radial loads. On the other hand, if only one thrust transmission path is used as in the present embodiment, the number of rolling bearings can be reduced. In the present embodiment, the other link path connecting the thrust member 23 and the driven member 21 does not transmit the thrust load, and the load acting on the rotating pair portion prevents the nut member 2 from rotating. The radial load corresponding to one of the couples is mainly. This radial load is smaller than the thrust load, and a large radial load does not act between the screw shaft 1 and the nut member 2 due to frictional resistance without incorporating a rolling bearing.

  FIG. 7 is a schematic view of a link mechanism formed in the linear actuator device according to the second embodiment of the present invention. As shown in this figure, the linear actuator device configured as described above has a node L23 formed on the thrust member 23, a node L24 formed on the link member 24, and a node L27 formed on the link member 27. The nodes L22a and L22b formed on the link member, the node L30 formed on the link member 30, the node L33 formed on the link member 33, the node L21 formed on the driven member 21, and the node L23. Rotating pair J1 connecting node L24 and node L24, rotating pair J28 connecting node L23 and node L27, rotating pair J29 connecting node 27 and node L22a, node L22a, node L24, node L30 and node Rotating pair J26 that connects L22b, Rotating pair J35 that connects node L22b and node L33, Rotating pair J32 that connects node L21 and node L30, and Node L21 And a turning pair portion J34 for connecting the section L33.

  The first parallel link mechanism 71A is formed by a node L23, a node L24, a node L27, and a node L22a, and the second parallel link mechanism 72A is a node L21, a node L30, a node L33, and a node L22b. Is formed by.

  Since the node L23 in the first parallel link mechanism 71A is formed on the thrust member 23 fixed to the nut member 2 via the uneven load prevention mechanism 60, the node L23 is a node that cannot rotate relative to the nut member 2. Yes. Further, in the first parallel link mechanism 71A, the node L23 and the node L22a arranged opposite to the node L23 are always held in parallel, so that the node L22a translates with respect to the node L23 (the thrust member 23 and the nut member 2). Can rotate but cannot rotate relatively.

  On the other hand, the node L <b> 21 in the second parallel link mechanism 72 </ b> A is formed on the driven member 21, and thus is a node that cannot rotate relative to the driven member 21. Further, in the second parallel link mechanism 72A, the node L21 and the node 22b opposed to the node L21 are always held in parallel, so that the node 22b can translate with respect to the node L21 (the driven member 21). Can not rotate relatively.

  Here, the link member 20 in the first embodiment has been used as a node shared by the two parallel link mechanisms 71 and 27 from the viewpoint of simplifying the component configuration of the linear actuator device. The link member 22 in the form is used as a node L22a that connects the shafts 26 and 29 in the first parallel link mechanism 71A, and a node that connects the shaft 32 and the shaft 35 in the second parallel link mechanism 72A. Used as L22b. In this way, the first parallel link mechanism 71A has a node L22a disposed opposite to the node that cannot rotate relative to the nut member 2, and the second parallel link mechanism 72A has a node that cannot rotate relative to the driven member 21. Even if the oppositely arranged nodes L22b are fixed to the same link member 22 independently, the nut member 2 can be prevented from rotating (rotating) around the screw shaft 1 by the connecting mechanism 200A.

  Accordingly, also in the present embodiment, the nut member 2 is prevented from rotating due to a couple of forces acting via the two nodes L24 and L27 disposed opposite to each other in the first parallel link mechanism 71A. It is possible to avoid a radial load acting between 2 and the screw shaft 1. That is, according to the present embodiment, it is possible to suppress the generation of a radial load, so that the durability of the rolling screw mechanism 100 can be improved.

  In the present embodiment, the node L22a in the first parallel link mechanism 71A and the node L22b in the second parallel link mechanism 72A are formed separately on the link member 22, and the angle formed by these two nodes L22a and L22b. Is preferably close to a right angle (90 degrees). Furthermore, if the first parallel link mechanism 71A and the second parallel link mechanism 72A are formed in a state close to a rectangle (or a square), it becomes easy to make the angle formed by the nodes L24 and L30 close to a right angle. As described above, when the angles of the nodes L24 and L30 are close to 90 degrees, the frictional resistance generated in the coupling mechanism when the thrust member 23 and the driven member 21 are slightly displaced increases depending on the displacement direction. This can be suppressed.

  FIG. 8 is a side view of a lift device for a forklift according to a third embodiment of the present invention, and FIG. 9 is a cross-sectional view taken along line EE in FIG.

  The lift device for a forklift shown in this figure moves up and down a fork member 39 by moving up and down an inner frame 38 supported by an outer frame 37 so as to be movable up and down. The lift device includes a rolling screw mechanism 100, a coupling mechanism 200 </ b> A, and an inner frame 38 that is a driven member of the rolling screw mechanism 100. It is assumed that two sets of such lift devices are mounted in pairs per vehicle forklift.

  The inner frame 38 is supported so as to be vertically movable with respect to the outer frame 37 supported by the vehicle body of the forklift, and the fork member 39 is supported so as to be vertically movable relative to the inner frame 38. . A sprocket 40 is rotatably attached to the upper end portion of the inner frame 38. One end of the chain 41 combined with the sprocket 40 is fixed to the upper part of the outer frame 37, and the other end of the chain 41 is fixed to the fork member 39. The inner frame 38 is guided in linear motion by the outer frame 37 and supported by the fork member 39 via a roller 42 that is rotatably supported on the upper portion of the outer frame 37 and a roller 43 that is rotatably supported on the lower portion of the inner frame 38. It is supported so that it does not incline due to the moment caused by the working load. The fork member 39 is linearly guided by the inner frame 38 via two rollers 44 rotatably supported on the upper and lower portions of the fork member 39 and is supported so as not to be inclined by a moment due to a cargo load acting on the fork member 39. Has been.

  The screw shaft 1 of the rolling screw mechanism 100 is rotatably supported by two radial bearings 45 attached to the upper and lower sides of the outer frame 37 and a thrust bearing 46 attached to the upper part of the outer frame 37, and includes a gear train 47 and a brake. It is rotationally driven by a motor 49 through a holding device 48. The nut member 2 of the rolling screw mechanism is connected to the inner frame 38 via the linear actuator mounting mechanism 50 in the second embodiment.

  When the motor 49 rotates and the screw shaft 1 rotates, the nut member 2 linearly moves up and down, and the inner frame 38 connected to the nut member 2 via the connection mechanism 200A described in the second embodiment. Drive up and down. At that time, the sprocket 40 at the upper end of the inner frame 38 functions as a moving pulley, and linearly drives the fork member 39 up and down at a speed that is twice as fast as the inner frame 38 moves linearly with respect to the outer frame 37.

  In the lift device, the inner frame 38 corresponds to the driven member 21 in the second embodiment, and the outer frame 39 corresponds to the guide member of the inner frame 38. This type of lift device is manufactured such that the direction in which the driven inner frame 38 is linearly guided by the outer frame 37 and the direction of the screw shaft 1 that is rotationally supported by the outer frame 37 always coincide with each other. There is no guarantee. Further, as the fork member 39 moves up and down, the distance between the roller 42 and the roller 43 may change, and the amount of inclination of the inner frame 38 relative to the outer frame 37 may change.

  However, according to the present embodiment, even if the distance between the nut member 2 and the driven inner frame 38 is changed due to such factors, the screw shaft 1 is used for the reason described in the second embodiment. It is possible to prevent a large radial load from acting between the nut member 2 and the nut member 2. Further, the driven inner frame 38 is prevented from rotating around the axis of the linear motion by the outer frame 37, and the nut member 2 connected to the inner frame 38 by the coupling mechanism 200A is also prevented from rotating and converted to rotational linear motion. Although functioning as a mechanism, as described above, rotation is prevented by the couple, so that a large radial load does not act on the screw shaft 1. As a result, according to the present embodiment, it is possible to prevent the life of the lift device and the forklift from being reduced.

  DESCRIPTION OF SYMBOLS 1 ... Screw shaft, 2 ... Nut member, 3 ... Driven member, 4 ... Link member, 5 ... Thrust member, 6 ... Half moon shoe, 7 ... Intermediate plate, 8 ... Pin, 9 ... Link member, 10 ... Shaft, 11 ... thrust ball bearing, 12 ... needle roller bearing, 13 ... link member, 14 ... shaft, 15 ... thrust ball bearing, 16 ... needle roller bearing, 17 ... shaft, 18 ... thrust ball bearing, 19 ... needle roller bearing, 20 ... Link member (intermediate member), 21 ... driven member, 22 ... link member (intermediate member), 23 ... thrust member, 24 ... link member, 25 ... thrust ball bearing, 26 ... shaft, 27 ... link member, 28 ... shaft , 29 ... Shaft, 30 ... Link member, 31 ... Thrust ball bearing, 32 ... Shaft, 33 ... Link member, 34 ... Shaf 35 ... Shaft, 36 ... Thrust ball bearing, 37 ... Outer frame, 38 ... Inner frame, 39 ... Fork member, 40 ... Sprocket, 41 ... Chain, 42 ... Roller, 43 ... Roller, 44 ... Roller, 45 ... Radial bearing , 46: Thrust bearing, 47: Gear train, 48 ... Holding device, 49 ... Motor, 60 ... Unbalanced load prevention device, 71 ... First link mechanism, 72 ... Second link mechanism, 100 ... Rolling screw mechanism, 200 ... Connection mechanism

Claims (6)

A rolling screw mechanism having a screw shaft having a spiral groove formed on the outer peripheral surface, and a nut member that contacts the screw shaft via a rolling element that rolls on the spiral groove;
A driven member whose movement direction is constrained on a straight line by the guide member and linearly driven by the rolling screw mechanism;
A rolling mechanism for connecting the rolling screw mechanism and the driven member;
The coupling mechanism is
A four-joint first parallel link mechanism having one joint that is not rotatable relative to the nut member about a central axis of the screw shaft;
A four-joint second parallel link mechanism having one joint that is not rotatable relative to the driven member around its linear motion direction;
The first parallel link mechanism is disposed opposite to a node that is not rotatable relative to the nut member, and the second parallel link mechanism is disposed opposite to a node that is not rotatable relative to the driven member. A linear actuator device comprising an intermediate member to which a knot is fixed. The linear actuator device according to claim 1,
The linear actuator device according to claim 1, wherein the first joint of the first parallel link mechanism and the first joint of the second parallel link mechanism fixed to the intermediate member are the same joint. In the linear actuator device according to claim 1 or 2,
In the first parallel link mechanism, at least one of two nodes adjacent to the one node that cannot rotate relative to the nut member, and in the second parallel link mechanism, relative rotation with respect to the driven member is impossible. A linear actuator device characterized in that a thrust from the rolling screw mechanism is transmitted to the driven member with at least one of two nodes adjacent to one node. The linear actuator device according to claim 3,
In the first parallel link mechanism and the second parallel link mechanism, there is further provided a rolling bearing for thrust load installed between a node that transmits a thrust from the rolling screw mechanism and a node adjacent to the node. A characteristic linear actuator device. The linear actuator device according to claim 4, wherein
Of the first parallel link mechanism and the second parallel link mechanism, the nut member in the first parallel link mechanism is a rotating pair of a node transmitting a thrust from the rolling screw mechanism and a node adjacent to the node. At least one of a pair that is not rotatable relative to a section and a section adjacent to the section is at least two rotating pairs arranged in the axial direction of the screw shaft with a gap therebetween. Linear actuator device characterized by being a rotating pair having In a forklift provided with the linear actuator device according to any one of claims 1 to 5 as a lift device for a fork member,
The driven member is an inner frame supported so as to be movable up and down by an outer frame supported by a vehicle body of the forklift,
A forklift characterized in that the fork member is raised and lowered when the inner frame is raised and lowered by driving of the rolling screw mechanism.

Images