Constant load compensation device, horizontal articulated robot, and vibration isolation mechanism

Abstract

This constant load compensating device is characterized by employing a mechanical self-weight compensating device including a link of which one end is pivotally mounted to a base, and a spring member of which one end is a fixed end and the other end is coupled to the link by way of a point of action vertically above a pivoting portion of the link with the base, wherein an operating body that is deflected by the rotation of the link while maintaining a fixed attitude is attached to the link, the mechanical self-weight compensating device compensates for self-weight torque of the link and the operating body by means of the elastic force of the spring member, irrespective of an angle of the link, and the direction of self-weight compensation is converted to a linear axis.

Description

Technical Field

[0001] The present invention relates to a mechanism for compensating for a fixed load such as its own weight, a fixed load compensating device, a horizontal articulated robot, and an anti-vibration mechanism.

Background Art

[0002] Conventionally, as mechanisms for industrially compensating for the weight of an object, counterweights, pressure by fluids (liquids / gases), and constant load springs have been widely used. However, these have problems in terms of the weight of the mechanism itself, the increase in peripheral equipment, and durability.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] On the one hand, in the case of the conventional self-weight compensation device as described above, if the method of Patent Document 1 is used, it is possible to compensate for the self-weight in the rotational direction that solves these problems. However, with the method of Patent Document 1, it is not possible to compensate for the self-weight in the linear axis direction, and the implementation on the device is limited. That is, the problem of the present invention is to compensate for the self-weight in the linear axis direction that is lightweight, simple, and durable.

Means for Solving the Problems

[0005] To solve the above problems, the load compensation direction of the load compensation device of Patent Document 1 is converted from the rotational axis direction to the linear axis direction. As one of the means, a method of forcibly converting with a linear guide shaft is presented. Also, by using a plurality of rotational axis load compensation devices and canceling each other out with their couples, a method of converting only in the linear axis direction is presented. Furthermore, in order to increase the stroke that can be load-compensated, a mechanism using gears or timing belts is also presented. Effect of the Invention

[0006] According to the present invention, the load compensation device can be used in the linear axial direction, which increases the degree of freedom in installation and contributes to energy saving.

[0007] One aspect of the present invention is a link having one end pivotally attached to a base, and one end being a fixed end and being located vertically above the pivotal part of the link and the base. or vertically downward a spring member having a point of action at the other end connected to the link, and an actuator that moves while maintaining a constant posture due to the rotation of the link is attached to the link, the A device using a mechanical weight compensation device that compensates for the weight torque of an operating body by the elastic force of the spring member without depending on the angle of the link, The actuating body moves in a first linear direction in response to an external force, and a part of the link moves in a second linear direction orthogonal to the first linear direction in response to the movement of the actuating body in the first linear direction. The other end of the spring member is connected to the part of the link via a wire. This is a constant load compensation device characterized in that the weight compensation direction is converted into a linear axis. [Brief description of the drawings]

[0008]

Figure 1

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Embodiments for Carrying Out the Invention

[0009] Hereinafter, the mechanism of the load compensation device according to the first embodiment of the present invention will be described.

[0010] In FIG. 1, the load compensation device 1 has a device base 2 as a base, and a device top plate 5 is supported by device support columns 3 and 4. The structure on the left side of the figure is the configuration of a self-weight compensation device using a rotating shaft shown in Patent Document 1. The link 13 rotates around the link rotation shaft 12, and a cam follower 14 is installed at its tip. A wire 16 extends toward the wire rotation shaft 15 with a connection point near its central axis, and is directly connected to a compression guide plate 18. The compression guide plate 18 is placed so as to compress a compression spring 17. Note that the device base 2 and the device top plate 5 are collectively referred to as a device frame. Also, the device base 2 is also referred to as a base.

[0011] The guide moving body 9 is restricted to move only in the vertically straight line direction by linear guides 6 and 7 installed on the left and right. This linear guide may be a simply tensioned wire guide or a linear motion guide or the like. The configuration may be determined in consideration of residual frictional resistance and cost. These linear guides 6 and 7 are connected to the device base 2 and the device top plate 5.

[0012] On the top plate 5 of the device, a variable magnification pulley 8 is installed. This pulley is installed to enlarge the movement amount of the original magnification timing belt 10 directly connected to the guide moving body 9. In FIG. 1, the radius is also set to 1:5 so that the movement amount is enlarged at a magnification of 1:5. As a result, the enlarged timing belt 11 generates a stroke five times that of the original magnification timing belt. However, the tension becomes one-fifth.

[0013] Now, the driving method of the device will be described below. Assume that a constant thrust of F (N) upward is generated in the enlarged timing belt 11. At this time, the thrust is converted by the variable magnification pulley 8, and a constant thrust (constant tension) of 5 × F (N) upward is generated in the original magnification timing belt. This force is transmitted to the guide moving body 9 and attempts to push up the cam follower 14 upward with a constant thrust of 5 × F (N). At this time, as shown in Patent Document 1, if the length of the link 13, the position of the link rotation axis 12, the position of the wire rotation axis 15, the natural length and the spring constant of the compression spring 17 are appropriately set, the restoring force of the compression spring 17 can balance with a constant thrust of 5 × F (N) regardless of the vertical position of the guide moving body.

[0014] At this time, while the cam follower 14 receives a vertical force, it also moves in the left-right direction with the link rotation axis 12 as the rotation center. Since this movement amount does not generate any thrust, the upper surface of the guide moving body 9 can freely move left and right by the cam follower 14. That is, the vertical acting point on the guide moving body moves left and right depending on the angle of the link 13. This movement of the acting point becomes a moment for rotating the guide moving body 9, but by restricting it with the linear guides 6 and 7, it is converted into load compensation on the vertical straight axis.

[0015] By using the present invention in this way, although there is contact between elements and frictional resistance generated in the driving part, a constant load can be compensated at any stroke position (vertical height). Further, by using a variable magnification pulley, the main body of the load compensation device can be manufactured compactly. Furthermore, by using a compression spring as the repulsion element, improvement in durability can be expected. This is because a tension spring is different from a compression spring, and stress concentrates on the hook portion, making it difficult to achieve durability.

[0016] Next, Example 2 will be described with reference to FIG. 2.

[0017] In FIG. 2, the load compensation device 19 uses two sets of the load compensation devices of Patent Document 1. The installation is symmetric with respect to the center plane of the original magnification timing belt 10. As a result, the left and right cam followers 14 move left and right on the upper surface of the guide moving body 9 in the same manner as in the case of FIG. 1, and although the acting points move left and right, the left and right acting points are symmetric with respect to the left and right and thus cancel each other out. As a result, the linear guides 6 and 7 do not receive a moment load, and the guide mechanism can be made to have a small load or simplified. In this way, by using a plurality of sets of the load compensation devices of Patent Document 1, simplification of the guide mechanism can be realized by a couple force.

[0018] FIG. 3 shows Example 3. The configuration of the load compensation device 20 is basically the same as that of the load compensation device 19 shown in FIG. 2. The difference is that the load compensation device 19 is arranged symmetrically with respect to the center plane of the original magnification timing belt 10, while FIG. 3 is arranged symmetrically with respect to the central axis of the original magnification timing belt 10. Thereby, the dimension in the left - right direction of the device can be shortened, and as a result, the entire device can be made compact.

[0019] FIG. 4 shows Example 4. The load compensation device 21 uses three sets of the rotating shaft load compensation devices of Patent Document 1. These three sets are arranged at equal circumferential intervals with the central axis of the original magnification timing belt 10 as the central axis. Thereby, similar to Examples 2 and 3, the moment of the guide moving body can be canceled out. Although not shown in the figures, by arranging them in line symmetry or plane symmetry like this, the rotational moments generated by multiple rotational axis load compensation devices can cancel each other out. It can be understood that this is regardless of whether there are three sets, four sets, or more. As a result, for example, even when there is no compression spring with an appropriate spring constant or no wire with sufficient tensile strength, it can be divided into several parts to compensate for a large upward thrust.

[0020] Fig. 5 shows Example 5. The symmetrical configuration is the same as that of Example 2, but in Example 5, instead of compensating for the tensile thrust in the upward direction, it has a structure that compensates for the pressing thrust in the downward direction. Specifically, the thrust applied downward by the enlarged rack gear 25 is converted into thrust and stroke by the pinion gear 23 and transmitted to the original-scale rack gear 24. The guide moving body 26 becomes a downward force in the figure and attempts to push down the cam follower 14. On the contrary, trying to resist with a certain reaction force is as described in Figs. 1 to 4. The only difference is that the component objects are arranged upside down.

[0021] Now, examples of applying the above load compensation device to various mechanical devices will be shown.

[0022] Fig. 6 shows an example of a horizontal articulated robot 27. Many horizontal articulated robots are vertically linearly moved and supported in the vertical direction as shown in the figure. At this time, in order to maintain the height of the horizontal articulated arm 33 in many cases, an actuator such as a motor constantly outputs thrust to hold its own weight. However, with this method, not only the moving thrust required in the up and down directions originally, but also the thrust for maintaining the self-weight is required, so it is not energy-saving because it constantly requires power, and there is a drawback that the size of the motor itself has to be made larger than necessary because a large amount of thrust is required.

[0023] Therefore, as shown in FIG. 6, a load compensation device 28 is used. The load compensation device 28 always compensates for the downward self-weight of the horizontal articulated arm 33 via a load compensation timing belt 31 and a pulley 32. This mechanism has already been described with reference to FIGS. 1 to 4. By adopting the configuration as shown in FIG. 6, the actuator thrust required to move the horizontal articulated arm 33 up and down only needs to overcome the thrust calculated by its specified acceleration and moving mass and the frictional force generated in each part. It should be extremely small, and a low-power actuator should be sufficient.

[0024] As described above, a horizontal articulated robot has been given as one of the application examples. Needless to say, industrially, it is applicable not only to robots but also to all devices that require compensation for a constant load in a linear direction. For example, it can also be used for elevators with a small step difference, and hoist cranes are applicable from large ones used for tankers to those manually used in factories. Furthermore, although not shown, it is also applicable to a stair lift for a wheelchair that can be seen at a train station or the like. This is because although the stair lift moves diagonally, this device can be applied regardless of whether the linear axis is vertical, horizontal, or diagonal as long as it is a linear axis. If a constant load can always be compensated, it will lead to energy savings.

[0025] Next, an application example will be shown in Fig. 7. Fig. 7 shows the vibration-isolated moving vehicle 34. The vibration-isolated moving vehicle can move by tires 40. At this time, if a load compensation device 35 is suspended from the ceiling of the main frame 36 supported by the tires 40 and coupled to the vibration-isolated table 37 via an extended timing belt 11, it is clear that the vibration-isolated table 37 will not directly transmit the vibration caused by the unevenness of the road surface and will try to stay in place due to its inertial force. Thus, a vibration isolation mechanism can be achieved. However, at this time, if only this mechanism is used, it is expected that the posture of the vibration-isolated table 37 will gradually deviate due to the influence of friction or the like and be displaced to an unintended posture. Therefore, in order to gently return to the origin, it is advisable to provide a position return spring 38 and a damper 39 with a minimum strength as shown in the figure. The position return spring 38 can be a coil spring or a leaf spring. There are also various types of dampers 39 such as those using liquid or magnetic force, but the simplest one may be the one using contact friction.

[0026] As described above, by using the mechanism of the present invention, not only can the thrust specification of the active vertical drive be relaxed like that of a horizontal articulated robot, but also the influence of the vibration passively applied from the outside can be minimized.

[0027] Fig. 8 shows another example of a vibration isolation mechanism. The vibration isolation device 41 is assumed to protect a vibration isolation target 45 such as a house or a commodity shelf from an earthquake. Conventional vibration isolation devices are basically devices that only cancel lateral shaking and do not cope with vertical shaking such as a direct hit type. However, by using the device of the present invention, vertical shaking can also be canceled as shown in this figure.

[0028] Installing the position return spring 38 and the damper 39 at the lower part of the vibration isolation base 43 is the same as in the example of Fig. 7. A load compensation device 44 is also installed here. Although it is of course possible to use a hanging mechanism as in Fig. 6, in Fig. 7, a supporting mechanism from below is adopted. In this case, the structure of Example 5 may be applied.

[0029] In this way, a vibration isolation device that protects an object from an earthquake or a large shake can be realized.

[0030] Now, the embodiments of the present invention have been described as above. However, as long as the same operation can be obtained, it is not necessarily required to be the mechanical elements as illustrated. For example, although a pulley or a rack and pinion mechanism is illustrated for the zoom mechanism, a combination gear such as a spur gear may be used, or a mechanism such as a continuously variable transmission may be used.

Industrial Applicability

[0031] By using the present invention in this way, it is possible to compensate for a constant thrust that always occurs in the linear direction. As a result, not only can the self-weight compensation in the vertical direction of a horizontal articulated robot or a hoist crane be achieved, but also the load compensation in an oblique direction such as a staircase can be achieved. Moreover, it is possible to suppress external vibrations such as earthquakes. In addition, since the stroke can be magnified by using gears and pulleys in combination, the weight and size of the device can be reduced, so that it can be applied to various industrial products.

Explanation of Reference Numerals

[0032] 1 Load compensation device 2 Device base 3 Device support column 4 Device support column 5 Device top plate 6 Linear guide 7 Linear guide 8 Zoom pulley 9 Guide moving body 10 Original magnification timing belt 11 Enlargement timing belt 12 Link rotation shaft 13 Link 14 Cam follower 15 Wire rotation shaft 16 Wire 17 Compression spring 18 Compression guide plate 19 Load compensation device 20 Load compensation device 21 Load compensation device 22 Load compensation device 23 Pinion gear 24 Original Rack Gear 25 Enlarged Rack Gear 26 Guide Mover 27 Horizontal Articulated Robot 28 Load Compensation Device 29 Device Base 30 Vertical Support Column 31 Load Compensation Timing Belt 32 Pulley 33 Horizontal Articulated Arm 34 Vibration Isolation Mover 35 Load Compensation Device 36 Main Frame 37 Vibration Isolation Table 38 Position Return Spring 39 Damper 40 Tire 41 Vibration Isolation Device 42 Ground / Foundation 43 Vibration Isolation Base 44 Load Compensation Device 45 Vibration Isolation Target

Claims

1. A mechanical self-weight compensation device having a link pivotally attached at one end to a base, and a spring member having one end as a fixed end and the other end connected to the link through an action point vertically above or below the pivotal attachment portion of the link with the base, wherein an operating body that moves while maintaining a constant posture due to the rotation of the link is attached to the link, and the self-weight torque of the link and the operating body is compensated by the elastic force of the spring member without depending on the angle of the link. The device uses a mechanical self-weight compensation device, The operating body moves in a first linear direction in response to an external force, A part of the link moves in a second linear direction orthogonal to the first linear direction in response to the movement of the operating body in the first linear direction, The other end of the spring member is connected to the part of the link via a wire, A constant load compensation device characterized in that its self-weight compensation direction is converted into a linear axis.

2. The constant load compensation device according to claim 1, characterized in that the durability is enhanced by using a compression spring as the spring member.

3. The constant load compensation device according to claim 1, characterized in that a plurality of sets of the mechanical self-weight compensation devices are used to cancel out the generated thrust in a direction other than a desired linear axis.

4. A horizontal articulated robot characterized in that the output of an actuator is suppressed by using the constant load compensation device according to any one of claims 1 to 3.

5. A vibration isolation mechanism characterized in that external vibration is suppressed by using the constant load compensation device according to any one of claims 1 to 3.

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