Tension adjustment mechanism

Abstract

To provide a tension adjustment mechanism which is excellent in a space saving property in a belt mechanism and applies a predetermined tension to a belt corresponding to variance in dimensions of components constituting the belt mechanism.SOLUTION: A tension adjustment mechanism 6 for fixing a tension of a toothed belt 4 bridging a space between a driving pulley 2 and a driven pulley 3 comprises: a driven pulley pedestal 61 which freely rotatably supports the driven pulley 3; mounting parts 62A and 62B which are provided in a device body 9 and guide the driven pulley pedestal 61 in a bridging direction X in a slidable manner; a coil spring 63 which energizes the driven pulley pedestal 61 in a direction away from the driving pulley 2; and a spring holder 64 which is fixed on an inner peripheral side of the toothed belt 4 and supports the coil spring 63. In the spring holder 64, there is formed a long hole 644 which is longer in the bridging direction X than a body side screw hole 91 which is formed in the device body 9. A fastening screw 65 is inserted through the long hole 644 and threaded into the body side screw hole 91, and the spring holder 64 is fixed to the device body 9.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a tension adjusting mechanism for adjusting the tension of a toothed belt that is installed between a drive pulley and a driven pulley. [Background technology]

[0002] For applications such as printer carriage units and air conditioner cleaning units, a belt mechanism is used in which a toothed belt is stretched between a drive pulley and a driven pulley, and a moving body (such as a printer carriage print head) is moved back and forth between the pulleys via the toothed belt.This belt mechanism has traditionally been attached to the main body of devices such as printers and air conditioners and is widely used. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 7-125369 [Patent Document 2] Japanese Patent Application Laid-Open No. 2008-296474 [Patent Document 3] Japanese Patent Application Laid-Open No. 2004-148727 Summary of the Invention [Problem to be solved by the invention]

[0004] In a belt mechanism having a moving body as described above, it is necessary to maintain good meshing of the toothed belt in order to improve the positional accuracy of the reciprocating moving body. Therefore, FIG. 3 of Patent Document 1 discloses an embodiment in which a spring applies a biasing force to the toothed belt while the toothed belt is suspended between a pair of pulleys, widening the center distance between the pulleys to impart tension to the toothed belt, and a tension adjustment mechanism is added that can automatically adjust the tension to be constant while the belt is running.

[0005] However, in the method shown in FIG. 3 of Patent Document 1, in which the spring connected to the driven pulley is fixed directly to the device body, it is necessary to secure space for attaching the spring to the device body, which requires extra space in the device.

[0006] To solve this problem, Patent Document 2 discloses a tension adjustment mechanism in which a spring for widening the center distance between the pulleys is not attached directly to the device body, but is connected to the device body via a base that can move in the belt installation direction. With this structure, there is no need to reserve space in the device body for attaching a spring. Here, the installation direction refers to the direction connecting the drive shaft (center) of the drive pulley on which the belt is installed and the rotation shaft (center) of the driven pulley.

[0007] However, the tension adjustment mechanism of Patent Document 2 has a problem in that the tension of the spring changes depending on the dimensional errors of the parts that make up the belt mechanism, resulting in variations in the tension applied to the belt when it is assembled to the device main body.

[0008] Furthermore, when used in a device body with a long center distance between the pulleys, the difference in thermal expansion coefficient between the device body and the belt increases dimensional errors depending on the temperature during assembly, resulting in greater variation in the initial tension of the belt, which was also an issue.

[0009] To solve this problem, Patent Document 3 discloses a tension adjustment mechanism that includes an adjustment screw for adjusting the center distance of the pulleys, and that allows the center distance of the pulleys to be mechanically adjusted by using the screw to adjust the spring length of the spring that applies tension to the belt.

[0010] However, the tension adjustment mechanism of Patent Document 3 has a complex mechanism for adjusting the center distance of the pulleys, which eliminates the advantage of space-saving within the device. In addition, because tensioning the belt relies on mechanical elements, it is difficult to precisely sense the tension when assembling the belt, which inevitably results in rough tension adjustment.

[0011] In order to solve the above problems, it was considered desirable to have a tension adjustment mechanism in a belt mechanism having a moving body that moves back and forth between a pair of pulleys in the direction in which the belt is laid, which does not require extra space for installing a spring within the device and can adjust the center distance of the pulleys without relying on mechanical elements when assembling the belt.

[0012] Therefore, the present invention aims to provide a tension adjustment mechanism for a belt mechanism having a moving body that moves back and forth between a pair of pulleys in the direction in which the belt is laid, which is space-saving and can apply a predetermined tension to the belt in response to dimensional variations in the parts that make up the belt mechanism. [Means for solving the problem]

[0013] The present invention provides a tension adjustment mechanism for maintaining constant tension in a toothed belt installed between a drive pulley and a driven pulley, a driven pulley base that rotatably supports the driven pulley; a mounting portion provided on a device body to which the tension adjustment mechanism is attached, and configured to slidably guide the driven pulley base in an installation direction, which is a direction connecting a drive shaft of the drive pulley on which the toothed belt is installed and a rotation shaft of the driven pulley; a biasing member that biases the driven pulley base in a direction away from the drive pulley; a support member fixed to an inner peripheral side of the toothed belt stretched between the drive pulley and the driven pulley, and supporting the biasing member; The support member has a long hole formed in it that is longer in the installation direction than the screw hole formed in the device main body, and a screw is inserted through the long hole and threaded into the screw hole, thereby fixing the support member to the device main body.

[0014] According to the above configuration, the biasing member moves the driven pulley away from the drive pulley via the driven pulley base, thereby increasing the axial distance between the drive pulley and the driven pulley, thereby applying tension to the toothed belt and automatically adjusting the tension of the toothed belt while it is running. Furthermore, since the support member that supports the biasing member is fixed to the inner peripheral side of the toothed belt that is stretched between the drive pulley and the driven pulley, the tension adjustment mechanism can be disposed on the inner peripheral side of the stretched toothed belt, thereby achieving space savings in a layout that includes the tension adjustment mechanism. Furthermore, the mounting portion allows the driven pulley base to slide in the installation direction, and the support member has a long hole formed therein that is longer in the installation direction than the screw hole formed in the device main body. Therefore, when fixing the support member that supports the urging member to the device main body, by selecting which position of the long hole formed in the support member to align with and screw into the screw hole provided in the device main body, it is possible to make fine adjustments to the degree of expansion and contraction of the urging member that applies tension to the toothed belt, the distance between the drive pulley and the driven pulley, and the like.

[0015] Furthermore, the present invention provides the above-mentioned tension adjustment mechanism, the biasing member is a coil spring, the driven pulley base is provided with a base-side protrusion into which the coil spring is inserted, and a base-side locking portion connected to the base-side protrusion and locking one end of the coil spring, The support member may be characterized by having a support member side protrusion portion that faces the base side protrusion portion in the installation direction and into which the coil spring is inserted, and a support member side locking portion that is connected to the support member side protrusion portion and locks the other end side of the coil spring.

[0016] According to the above configuration, when fixing the support member to the device main body while biasing the coil spring against the driven pulley base, the base-side protrusion provided on the driven pulley base is inserted into one end of the coil spring to engage the one end of the coil spring with the base-side locking portion, and the support member-side protrusion provided on the support member is inserted into the other end of the coil spring to engage the other end of the coil spring with the support member-side locking portion, thereby facilitating assembly of the coil spring. In addition, since the coil spring is engaged with the base side protrusion and the support member side protrusion, which are opposite in the installation direction, inserted, the direction in which the coil spring biases the driven pulley base can be stabilized in the installation direction. The base-side protrusion and the support-member-side protrusion into which the coil spring is inserted are formed in a substantially cylindrical shape.

[0017] Furthermore, the present invention provides the above-mentioned tension adjustment mechanism, It may also be characterized in that the base side protrusion and the support member side protrusion are formed to protrude in the installation direction so that when the opposing base side protrusion and support member side protrusion are in contact, the elastic force due to compression of the coil spring becomes a predetermined value.

[0018] According to the above configuration, the degree of compression (elastic force) of the coil spring that applies the desired tension to the toothed belt can be achieved when the base-side protrusion and the support-member-side protrusion are in contact with each other. As a result, when assembling the coil spring, by fixing the support member to the device main body with the opposing base-side protrusion and support-member-side protrusion in contact with each other, the desired tension can be applied to the toothed belt, making it easy to set the tension of the toothed belt.

[0019] Furthermore, the present invention provides the above-mentioned tension adjustment mechanism, The device may be characterized in that an anti-slip surface is provided on at least one of a contact surface of the device body with the support member and a contact surface of the support member with the device body.

[0020] According to the above configuration, it is possible to prevent the support member from shifting in the installation direction when a large fluctuation in tension occurs in the toothed belt.

[0021] Furthermore, the present invention provides the above-mentioned tension adjustment mechanism, The length of the base side protrusion in the installation direction may be longer than the length of the support member side protrusion in the installation direction, or the length of the support member side protrusion in the installation direction may be longer than the length of the base side protrusion in the installation direction.

[0022] According to the above configuration, by making the length of the base-side protrusion in the installation direction longer than the length of the support-member-side protrusion in the installation direction, the base-side protrusion can be inserted into the coil spring so that the center of gravity of the coil spring is supported by the base-side protrusion. This makes it difficult for the coil spring to come off the base-side protrusion when, during the assembly of the tension adjustment mechanism, the base-side protrusion is inserted into one end of the coil spring and then the support-member-side protrusion is inserted into the other end of the coil spring. In other words, this makes it easier to assemble the tension adjustment mechanism. It is preferable that the length of the base-side protrusion in the installation direction be approximately twice (1.5 to 2.5 times) the length of the support-member-side protrusion in the installation direction. Furthermore, by making the length of the support member protrusion in the installation direction longer than the length of the base protrusion in the installation direction, the support member protrusion can be inserted into the coil spring so that the center of gravity of the coil spring is supported by the support member protrusion. This makes it difficult for the coil spring to come off the support member protrusion when inserting the support member protrusion into the other end of the coil spring and then inserting the base protrusion into one end of the coil spring during the assembly of the tension adjustment mechanism. In other words, this makes it easier to assemble the tension adjustment mechanism. Note that the length of the support member protrusion in the installation direction is preferably about twice (1.5 to 2.5 times) the length of the base protrusion in the installation direction. Here, the length of the base-side protrusion in the installation direction means the maximum length of the base-side protrusion in the installation direction, which corresponds to the length of the central axis of the base-side protrusion. The length of the support-side protrusion in the installation direction means the maximum length of the support-side protrusion in the installation direction, which corresponds to the length of the central axis of the support-side protrusion. [Effects of the Invention]

[0023] In a belt mechanism having a moving body that moves back and forth between a pair of pulleys in the direction in which the belt is installed, a tension adjustment mechanism can be provided that is space-saving and can apply a predetermined tension to the belt in response to dimensional variations in the parts that make up the belt mechanism. [Brief explanation of the drawings]

[0024] [Figure 1] FIG. 2 is a perspective view of the belt mechanism of the present embodiment. [Figure 2] FIG. 2 is a perspective view of a tension adjusting mechanism in the belt mechanism of the present embodiment. [Figure 3] FIG. 2 is a cross-sectional view of the tension adjustment mechanism of the present embodiment. [Figure 4] FIG. 2 is a perspective view of the tension adjustment mechanism of the present embodiment. [Figure 5] FIG. 2 is a schematic explanatory diagram of a belt mechanism according to the embodiment. [Figure 6] FIG. 10 is a cross-sectional view of a tension adjustment mechanism according to Modification 1. [Figure 7] 10A and 10B are explanatory diagrams of an assembly operation of the tension adjusting mechanism according to the first modified example. [Figure 8] FIG. 10 is a cross-sectional view of a tension adjustment mechanism according to Modification 2. DETAILED DESCRIPTION OF THE INVENTION

[0025] (Embodiment) As shown in FIG. 1, this embodiment is an example in which a tension adjustment mechanism 6 according to the present invention is applied to a belt mechanism 1 that is attached to a device main body 9 that is generally used in general industrial applications and that includes a moving body 5 (such as a printer carriage print head) that moves back and forth a predetermined distance between a driving pulley 2 and a driven pulley 3 via a toothed belt 4. The tension adjustment mechanism 6 keeps the tension of the toothed belt 4 constant.

[0026] (Belt mechanism 1) As shown in FIG. 1, the belt mechanism 1 includes a drive pulley 2 that is driven by a drive source (e.g., a servo motor) to be able to rotate forward and backward, a driven pulley 3 that is supported so as to be able to rotate freely, an endless toothed belt 4 that is wound between the drive pulley 2 and the driven pulley 3, a moving body 5 that is attached to the toothed belt 4, and a tension adjustment mechanism 6 that keeps the tension of the toothed belt 4 that is stretched between the drive pulley 2 and the driven pulley 3 constant. When the toothed belt 4 attached with the moving body 5 is used for general industrial purposes, the tension of the toothed belt 4 when stationary may be at a level that does not cause the toothed belt 4 to slacken, for example, about 1 N / 1 mm width of belt (also 1 N / 1 mm width of belt in this embodiment).

[0027] 1 to 5, for convenience, the direction of the toothed belt 4 installed between the drive pulley 2 and the driven pulley 3, i.e., the direction connecting the drive shaft 21 (center) of the drive pulley 2 and the rotation shaft 616 (center) of the driven pulley 3, will be described as the installation direction X (the direction from the drive pulley 2 toward the driven pulley 3 is the +X direction, and the opposite direction is the -X direction). Also, the direction perpendicular to the installation direction X and parallel to the radial direction of the drive pulley 2 (driven pulley 3) will be described as the up-down direction (see FIG. 2).

[0028] (Drive pulley 2 and driven pulley 3) The drive pulley 2 is connected to a drive source via a drive shaft 21 and is driven by the drive source to be able to rotate forward and backward. The drive pulley 2 is a toothed pulley, and has grooves formed on its outer periphery that correspond to the tooth shape of the toothed belt 4 (for example, a tooth shape commonly known as straight teeth).

[0029] The driven pulley 3 is rotatably supported on a rotary shaft 616 fixed to a driven pulley base 61 of the tension adjusting mechanism 6, which will be described later, and rotates in response to the running of the toothed belt 4. Like the driving pulley 2, the driven pulley 3 may have grooves formed on its outer periphery that correspond to the tooth shape of the teeth of the toothed belt 4, or may be a flat pulley (idler pulley) with a flat outer periphery.

[0030] In the pulley layout of the belt mechanism 1 of this embodiment, the distance between the axes of the drive pulley 2 and the driven pulley 3 is, for example, about 200 mm to 600 mm, and can be finely adjusted by moving the driven pulley base 61. Since the main purpose of the belt mechanism 1 is to move the moving body 5 back and forth via the toothed belt 4, rather than to transmit power via the toothed belt 4 (such as a reduction mechanism), the diameter of the drive pulley 2 and the diameter of the driven pulley 3 can be the same, and the speed ratio between the pulleys (diameter of the driven pulley 3 / diameter of the drive pulley 2) is set to, for example, about 1 (also 1 in this embodiment).

[0031] (Toothed belt 4) The toothed belt 4 is an endless intermeshing power transmission belt, and has a back portion (rubber-like elastic body) in which a core wire (tension body) extending in the longitudinal direction of the belt is embedded, and on the inner peripheral surface of the back portion, teeth are formed in a shape corresponding to the grooves formed on the outer periphery of the drive pulley 2. The teeth have, for example, a tooth shape called straight teeth, and are provided at predetermined intervals on the inner peripheral side of the toothed belt 4. The tooth shape of the toothed belt 4 may be a tooth shape called helical teeth (teeth with an oblique contact angle on the tooth surface) as long as synchronous transmission (meshing transmission) is possible.

[0032] (Mobile 5) As shown in FIG. 1, the moving body 5 is attached to the toothed belt 4 so as to be able to move back and forth between a pair of pulleys (between a driving pulley 2 and a driven pulley 3) via the toothed belt 4 in the direction X in which the toothed belt 4 is laid.

[0033] The moving body 5 is configured to have a predetermined shape and size depending on the use of the belt mechanism 1 (purpose of reciprocating movement) and user requirements (design of the device body 9 equipped with the belt mechanism 1). Since the shape and the like are arbitrary, in this embodiment, the moving body 5 is illustrated as a substantially rectangular parallelepiped shape as shown in FIG.

[0034] (Tension adjustment mechanism 6) As shown in FIGS. 2 and 4, the tension adjustment mechanism 6 includes a driven pulley base 61 that rotatably supports the driven pulley 3, mounting portions 62A and 62B that are provided on the device main body 9 and that slidably guide the driven pulley base 61 in the X direction in which the toothed belt 4 is laid, a coil spring 63 (a biasing member) that biases the driven pulley base 61 in a direction away from the drive pulley 2 (the +X direction in FIG. 2), a spring holder 64 (a support member) that is fixed to the inner peripheral side of the toothed belt 4 that is laid between the drive pulley 2 and the driven pulley 3 and that supports the coil spring 63, and a non-slip member 66 that is provided on the spring holder 64. The tension adjustment mechanism 6 uses a coil spring 63 to move the driven pulley 3 in the direction away from the drive pulley 2 (+X direction) via the driven pulley base 61, thereby increasing the axial distance between the drive pulley 2 and the driven pulley 3, thereby applying tension to the toothed belt 4 and automatically adjusting the tension of the toothed belt 4 while it is running.

[0035] (Driven pulley base 61) As shown in Figures 3 and 4, the driven pulley base 61 includes a base-side locking portion 611 that locks one end side 631 of the coil spring 63, a base-side protrusion portion 612 into which the coil spring 63 is inserted, a flat base portion 613, a slider 614A provided on the upper end side of the base portion 613, a slider 614B provided on the lower end side of the base portion 613, a cover body 615 that covers the driven pulley 3, and a rotating shaft 616 fixed to the base portion 613.

[0036] The base-side locking portion 611 is provided on the base portion 613, and has a locking surface 611A formed on the −X direction side, the locking surface 611A being larger than the outer periphery of the coil spring 63. One end side 631 of the coil spring 63 comes into contact with the locking surface 611A, whereby the one end side 631 of the coil spring 63 is locked to the locking surface 611A.

[0037] Base-side protrusion 612 is connected to base-side locking portion 611, and has a cylindrical shape with a diameter slightly shorter than the inner diameter of coil spring 63. Coil spring 63 is inserted into base-side protrusion 612 in such a manner that the inner peripheral surface of coil spring 63 faces the outer peripheral surface of base-side protrusion 612.

[0038] The slider 614A and the slider 614B each have a rectangular shape extending in the installation direction X. The slider 614A and the slider 614B are slidable in the installation direction X in a state where they are inserted between a groove 62A1 formed in an attachment portion 62A and a groove 62B1 formed in an attachment portion 62B, which will be described later.

[0039] The cover body 615 serves to protect the driven pulley 3 and the toothed belt 4. The rotary shaft 616 also serves to support the driven pulley 3 so that it can rotate freely.

[0040] The material of the driven pulley base 61 is not particularly limited as long as it is a material with sufficient rigidity, and may be, for example, a resin such as polypropylene resin or polyacetal resin, or a metal such as carbon steel, stainless steel, or aluminum alloy.

[0041] (Mounting parts 62A and 62B) The mounting portion 62A and the mounting portion 62B each have a rectangular shape extending in the installation direction X. A groove 62A1 is formed in the mounting portion 62A in the installation direction X, and a groove 62B1 is also formed in the mounting portion 62B in the installation direction X. With the sliders 614A and 614B of the driven pulley base 61 inserted between the grooves 62A1 and 62B1, the mounting portions 62A and 62B allow the driven pulley base 61 to slide while guiding the driven pulley base 61 in the installation direction X.

[0042] (coil spring 63) The coil spring 63 is a compression coil spring. The coil spring 63 of this embodiment is attached in a compressed state so that its length is shorter than its natural length when the belt mechanism 1 is assembled to the device main body 9. When the tension of the toothed belt 4 decreases, the repulsive force of the coil spring 63 applies tension to the toothed belt 4, thereby making it possible to maintain the tension of the toothed belt 4 at a predetermined value while it is running. The natural length of the coil spring 63 is longer than the sum of the length L11 in the -X direction of the base-side protrusion 612, which will be described later, and the length L12 in the +X direction of the support member-side protrusion 642. The natural length of the coil spring 63 is determined so that tension of the toothed belt 4 during running can be maintained at a predetermined value by applying tension to the toothed belt 4 by the repulsive force of the coil spring 63. The spring wire of the coil spring 63 is preferably an oil-tempered spring wire having a circular cross section or the like that conforms to JIS G3560:1994, and this embodiment also uses an oil-tempered spring wire having a circular cross section that conforms to the above standard.

[0043] (Spring holder 64) As shown in Figures 3 and 4, the spring holder 64 includes a support member side locking portion 641 that locks the other end side 632 of the coil spring 63, a support member side protrusion portion 642 into which the coil spring 63 is inserted, and a flat base portion 643 that is fixed to the device main body 9.

[0044] The support member side locking portion 641 is provided on a base portion 643, and has a locking surface 641A formed on the +X direction side, the locking surface 641A being larger than the outer periphery of the coil spring 63. The other end side 632 of the coil spring 63 comes into contact with the locking surface 641A, whereby the other end side 632 of the coil spring 63 is locked to the locking surface 641A.

[0045] The support member side protrusion 642 is connected to the support member side locking portion 641 and faces the base side protrusion 612 in the installation direction X. The support member side protrusion 642 has a cylindrical shape with a diameter slightly shorter than the inner diameter of the coil spring 63. In this embodiment, the diameter of the support member side protrusion 642 is the same as the diameter of the base side protrusion 612. Furthermore, the length L12 of the support member side protrusion 642 in the +X direction (the height of the cylindrical shape) is the same as the length L11 of the base side protrusion 612 in the -X direction (the height of the cylindrical shape). Note that the length L11 of the base side protrusion 612 in the -X direction refers to the maximum length of the base side protrusion 612 in the -X direction and corresponds to the length of the central axis of the base side protrusion 612. The length L12 of the support member side protrusion 642 in the +X direction refers to the maximum length of the support member side protrusion 642 in the +X direction and corresponds to the length of the central axis of the support member side protrusion 642. The coil spring 63 is inserted into the support member side protrusion 642 in such a manner that the inner peripheral surface of the coil spring 63 faces the outer peripheral surface of the support member side protrusion 642 . In this way, the coil spring 63 is locked in a state where it is sandwiched between the base-side locking portion 611 and the support member-side locking portion 641, with the base-side protrusion 612 and the support member-side protrusion 642 facing each other in the installation direction X being inserted. As a result, the driven pulley base 61 and the spring holder 64 are connected via the coil spring 63, with the direction in which the coil spring 63 biases the driven pulley base 61 stabilized in the installation direction X.

[0046] Furthermore, the diameter of the support member side protrusion 642 does not have to be the same as the diameter of the base side protrusion 612 as in this embodiment, and the diameter of the support member side protrusion 642 may be smaller or larger than the diameter of the base side protrusion 612.

[0047] Furthermore, the +X direction length L12 of the support member side protrusion 642 does not have to be the same as the -X direction length L11 of the base side protrusion 612 as in this embodiment, and the +X direction length L12 of the support member side protrusion 642 may be longer or shorter than the -X direction length L11 of the base side protrusion 612.

[0048] For example, as shown in FIG. 6 (Variation 1), the length L11' of the base protrusion 612' in the -X direction may be approximately twice (1.5 to 2.5 times) the length L12' of the support member protrusion 642' in the +X direction. By making the length L11' of the base protrusion 612' in the -X direction longer than the length L12' of the support member protrusion 642 in the +X direction, the base protrusion 612' can be inserted into the coil spring 63 so that the center of gravity of the coil spring 63 is supported by the base protrusion 612' (see FIG. 7). This makes it difficult for the coil spring 63 to detach from the base protrusion 612' during the assembly of the tension adjustment mechanism 6 when the base protrusion 612' is inserted into one end 631 of the coil spring 63 and then the support member protrusion 642' is inserted into the other end 632 of the coil spring 63. That is, the assembly work of the tension adjusting mechanism 6 can be made easier. If the difference between the length L11' of the base-side protrusion 612' in the -X direction and the length L12' of the support member-side protrusion 642' in the +X direction is too small, the coil spring 63 will easily detach from the base-side protrusion 612' during assembly, making the assembly difficult. On the other hand, if the difference between the length L11' of the base-side protrusion 612' in the -X direction and the length L12' of the support member-side protrusion 642' in the +X direction is too large, the direction in which the coil spring 63 biases the driven pulley base 61 will easily deviate from the installation direction X, making it difficult to stabilize the biasing direction. As a result, there is a risk that tension will not be applied to the toothed belt 4 in a stable manner. Therefore, in the first modification of FIG. 6, the length L11' of the base side protrusion 612' in the -X direction is preferably set to 1.5 to 2.5 times the length L12' of the support member side protrusion 642' in the +X direction.

[0049] 8 (Modification 2), the length L12" of the support member protrusion 642" in the +X direction may be approximately twice (1.5 to 2.5 times) the length L11" of the base protrusion 612" in the -X direction. By making the length L12" of the support member protrusion 642" in the +X direction longer than the length L11" of the base protrusion 612" in the -X direction in this way, the coil spring 63 can be inserted into the support member protrusion 642" so that the center of gravity of the coil spring 63 is supported by the support member protrusion 642". This makes it difficult for the coil spring 63 to come off the support member side protrusion 642" when inserting the support member side protrusion 642" into the other end side 632 of the coil spring 63 and then inserting the base side protrusion 612" into one end side 631 of the coil spring 63 during the assembly work of the tension adjustment mechanism 6. In other words, this makes it easier to assemble the tension adjustment mechanism 6. Here, if the difference between the length L12" of the support member-side protrusion 642" in the +X direction and the length L11" of the base-side protrusion 612" in the -X direction is too small, the coil spring 63 is likely to detach from the support member-side protrusion 642" during assembly, making the assembly difficult. On the other hand, if the difference between the length L12" of the support member-side protrusion 642" in the +X direction and the length L11" of the base-side protrusion 612" in the -X direction is too large, the direction in which the coil spring 63 biases the driven pulley base 61 is likely to deviate from the installation direction X, making it difficult to stabilize the biasing direction. As a result, there is a risk that tension may not be applied to the toothed belt 4 in a stable manner. Therefore, in the second modification of FIG. 8, the length L12" of the support member protrusion 642" in the +X direction is preferably 1.5 to 2.5 times the length L11" of the base protrusion 612" in the -X direction.

[0050] As shown in FIGS. 3 and 4, the base portion 643 has an elongated hole 644 formed therein that is longer in the installation direction X than the main body side screw hole 91 formed in the device main body 9. The fastening screw 65 is inserted through the elongated hole 644 and threaded into the main body side screw hole 91, whereby the spring holder 64 is fixed to the device main body 9 in a state where it is disposed on the inner peripheral side of the toothed belt 4 that is laid between the drive pulley 2 and the driven pulley 3. This allows the tension adjustment mechanism 6 to be disposed on the inner peripheral side of the laid toothed belt 4, thereby enabling space saving in the layout of the belt mechanism 1 that has the tension adjustment mechanism 6.

[0051] Here, the mounting portions 62A and 62B allow the driven pulley base 61 to slide in the installation direction X, and the base portion 643 of the spring holder 64 has an elongated hole 644 formed therein that is longer in the installation direction X than the main body-side screw hole 91 formed in the device main body 9. Therefore, when fixing the spring holder 64 that supports the coil spring 63 to the device main body 9, it is possible to select which position in the installation direction X of the elongated hole 644 formed in the base portion 643 is to be aligned with and screwed into the main body-side screw hole 91, thereby making it possible to fine-tune the degree of expansion and contraction of the coil spring 63 that applies tension to the toothed belt 4, the distance between the drive pulley 2 and the driven pulley 3, and the like.

[0052] In addition, in this embodiment, the base side protrusion 612 and the support member side protrusion 642 are formed to protrude in the installation direction X (the base side protrusion 612 protrudes in the -X direction, and the support member side protrusion 642 protrudes in the +X direction) so that the elastic force due to compression of the coil spring 63 becomes a preset value (a value that obtains an elastic force that can maintain the tension of the toothed belt 4 at a predetermined value while it is running) when the opposing contact surface 612A of the base side protrusion 612 and the contact surface 642A of the support member side protrusion 642 are in contact with each other.

[0053] According to the above configuration, the degree of compression of the coil spring 63, which provides an elastic force capable of maintaining the tension of the toothed belt 4 at a predetermined value while it is running, can be achieved in a state where the opposing contact surface 612A of the base-side protrusion 612 and the contact surface 642A of the support member-side protrusion 642 are in contact with each other. As a result, when assembling the coil spring 63 to the driven pulley base 61 and the spring holder 64, by fixing the spring holder 64 to the device main body 9 in a state where the opposing base-side protrusion 612 and the support member-side protrusion 642 are in contact with each other, it is possible to impart to the coil spring 63 an elastic force capable of maintaining the tension of the toothed belt 4 at a predetermined value while it is running, and it is possible to easily set the tension of the toothed belt 4.

[0054] The material of the spring holder 64 is not particularly limited as long as it has sufficient rigidity, and may be, for example, a resin such as polypropylene resin or polyacetal resin, or a metal such as carbon steel, stainless steel, or aluminum alloy.

[0055] (Anti-slip 66) The anti-slip device 66 is provided on the back surface (contact surface with the device body 9) of the base portion 643 of the spring holder 64. There is no particular limitation on the type of anti-slip device 66, but for example, the anti-slip device 66 may be provided by a method of increasing the coefficient of friction of the contact surface by performing knurling or shot blasting on the periphery of the body-side screw hole 91 of the device body 9 or on the entire contact surface between the base portion 643 and the device body 9, or by providing a material with a high coefficient of friction such as resin on the back surface of the base portion 643. The anti-slip device 66 can prevent the spring holder 64 from shifting in the installation direction X when there is a strong fluctuation in tension in the toothed belt 4.

[0056] (Device body 9) The device main body 9 in which the belt mechanism 1 equipped with the tension adjusting mechanism 6 is installed is not particularly limited and can be used for general purposes. As described above, the device body 9 is provided with the body-side screw hole 91 into which the fastening screw 65 is inserted and screwed through the elongated hole 644. The surface of the device body 9 that comes into contact with the base 643 of the spring holder 64 is subjected to an anti-slip treatment. The method of the anti-slip treatment is not particularly limited, but for example, the surface may be provided by a method that increases the coefficient of friction of the surface, such as knurling or shot blasting, or a material with a high coefficient of friction, such as resin, may be provided. In this embodiment, the surface of the device body 9 that comes into contact with the base 643 of the spring holder 64 is knurled to increase the coefficient of friction of the surface. In this embodiment, the anti-slip devices are provided on the base 643 and the device main body 9, but the anti-slip devices may be provided on either one of them.

[0057] (Assembly of belt mechanism 1 with tension adjustment mechanism 6) The belt mechanism 1 equipped with the tension adjusting mechanism 6 in this embodiment is assembled to the device main body 9 in the following procedure. (1) The driven pulley 3 is inserted onto the rotary shaft 616 of the driven pulley base 61 and screwed in with the driven pulley fastening screw 31, thereby rotatably fixing the driven pulley 3 to the rotary shaft 616. A toothed belt 4 is wound around a driving pulley 2 and a driven pulley 3 attached to a drive shaft connected to a drive source, and a moving body 5 is fixed to the toothed belt 4.

[0058] (2) The slider 614A and the slider 614B of the driven pulley base 61 are inserted between the groove 62A1 of the mounting portion 62A and the groove 62B1 of the mounting portion 62B. This allows the driven pulley base 61 to slide in the installation direction X while being held between the mounting portions 62A and 62B.

[0059] (3) The base-side protrusion 612 provided on the base-side locking portion 611 of the driven pulley base 61 is inserted into one end side 631 of the coil spring 63, and the one end side 631 of the coil spring 63 is locked to the locking surface 611A of the base-side locking portion 611. Subsequently, the support member-side protrusion 642 provided on the support member-side locking portion 641 of the spring holder 64 is inserted into the other end side 632 of the coil spring 63, and the other end side 632 of the coil spring 63 is locked to the locking surface 641A of the support member-side locking portion 641. Here, as shown in FIG. 6, if the length L11' of the base-side protrusion 612' in the -X direction is made longer than the length L12' of the support member-side protrusion 642 in the +X direction, the coil spring 63 can be inserted into the base-side protrusion 612' so that the center of gravity of the coil spring 63 is supported by the base-side protrusion 612' (see FIG. 7). This makes it difficult for the coil spring 63 to come off the base-side protrusion 612' when, during the assembly of the tension adjustment mechanism 6, the base-side protrusion 612' is inserted into one end 631 of the coil spring 63 and then the support member-side protrusion 642' is inserted into the other end 632 of the coil spring 63. In other words, the assembly of the tension adjustment mechanism 6 can be made easier.

[0060] In addition, the support member side protrusion 642 provided on the support member side locking portion 641 of the spring holder 64 may be inserted into the other end side 632 of the coil spring 63, and the other end side 632 of the coil spring 63 may be locked to the locking surface 641A of the support member side locking portion 641, and then the base side protrusion 612 provided on the base side locking portion 611 of the driven pulley base 61 may be inserted into one end side 631 of the coil spring 63, and the one end side 631 of the coil spring 63 may be locked to the locking surface 611A of the base side locking portion 611. Here, as shown in FIG. 8 , if the length L12" of the support member-side protrusion 642" in the +X direction is made longer than the length L11" of the base-side protrusion 612" in the -X direction, the support member-side protrusion 642" can be inserted into the coil spring 63 so that the center of gravity of the coil spring 63 is supported by the support member-side protrusion 642". This makes it less likely that the coil spring 63 will come off the support member-side protrusion 642" when, during the assembly of the tension adjustment mechanism 6, the support member-side protrusion 642" is inserted into the other end 632 of the coil spring 63 and then the base-side protrusion 612" is inserted into the one end 631 of the coil spring 63. In other words, the assembly of the tension adjustment mechanism 6 can be made easier.

[0061] (4) When the spring holder 64 is slid in the direction approaching the driven pulley base 61 (+X direction), the coil spring 63 is compressed, the driven pulley base 61 is biased, and in conjunction with the spring holder 64, it slides between the mounting portions 62A and 62B, and tension is applied to the toothed belt 4.

[0062] (5) The coil spring 63 is compressed until the contact surface 612A of the base side protrusion 612 and the contact surface 642A of the support member side protrusion 642 are in contact with each other. Then, the fastening screw 65 is inserted into the elongated hole 644 and screwed into the main body side screw hole 91.

[0063] In this case, as shown in Figure 5, if the axial distance between the drive pulley 2 and the driven pulley 3 is L, the distance from the drive shaft 21 of the drive pulley 2 to the main body side screw hole 91 is L1, and the distance from the center of the elongated hole 644 to the rotation axis 616 of the driven pulley 3 is L2, then if the elongated hole 644 is not an elongated hole (if the elongated hole 644 is the same size as the main body side screw hole 91), then L = L1 + L2, i.e., L1 = L - L2.

[0064] In this embodiment, if there is variation in L1 among individual device main bodies 9 or a change due to thermal expansion, the position at which the fastening screw 65 is inserted into the elongated hole 644 can be adjusted to adjust the distance L3 from the main body-side screw hole 91 to the center of the elongated hole 644, and the tension adjustment mechanism 6 can be assembled to the device main body 9. For example, if L1 has increased due to thermal expansion, the elongated hole 644 can be assembled so that it is positioned on the drive pulley 2 side with respect to the main body-side screw hole 91, and L = L1 + L2 - L3, thereby making it possible to satisfy L1 = L - L2 + L3. Even if L1 has increased, the belt mechanism 1 equipped with the tension adjustment mechanism 6 can be assembled to the device main body 9 without changing L or L2, which affect the tension of the toothed belt 4 (see FIG. 5).

[0065] In this way, when fixing the spring holder 64 that supports the coil spring 63 to the device main body 9, by selecting which position in the installation direction X of the elongated hole 644 formed in the base portion 643 is to be aligned with the main body side screw hole 91 and screwed into, it is possible to fine-tune the degree of expansion and contraction of the coil spring 63 that applies tension to the toothed belt 4, the distance between the drive pulley 2 and the driven pulley 3, etc.

[0066] As a result, the spring holder 64 is fixed to the device body 9, and the assembly of the belt mechanism 1 to the device body 9 is completed.

[0067] According to the above configuration, when the spring holder 64 is fixed to the device body 9 while the coil spring 63 is biased against the driven pulley base 61, the coil spring 63 can be easily assembled to the tension adjusting mechanism 6. Furthermore, since the spring holder 64 that supports the coil spring 63 is fixed to the inner peripheral side of the toothed belt 4 that is stretched between the drive pulley 2 and the driven pulley 3, the tension adjustment mechanism 6 can be positioned on the inner peripheral side of the stretched toothed belt 4, thereby enabling space saving in the layout of the belt mechanism 1 that has the tension adjustment mechanism 6.

[0068] (Operation of tension adjustment mechanism 6) If the tension of the toothed belt 4 decreases (slackens) for some reason while the toothed belt 4 is running, the coil spring 63 rebounds by the amount of slack and urges the driven pulley base 61, thereby widening the axial distance between the drive pulley 2 and the driven pulley 3. When the axial distance between the drive pulley 2 and the driven pulley 3 widens, the tension of the toothed belt 4 increases, so the slack in the toothed belt 4 is eliminated and the tension of the toothed belt 4 is automatically adjusted to be constant while it is running. [Example]

[0069] The tension adjusting mechanism of the present invention must have sufficient space and be easy to assemble so as to accommodate variations in the dimensions of the components of the belt mechanism. Therefore, in this example, tension adjusting mechanisms according to Example 1 and Comparative Examples 1 and 2 (hereinafter referred to as "test specimens") were fabricated, and disassembly inspections and assembly tests were carried out to carry out comparative verification. The present invention will be described in more detail below based on examples, but the present invention is not limited to these examples.

[0070] [Tension adjustment mechanism] The tension adjustment mechanism of Example 1 has the configuration of the above-described embodiment. Specifically, a spring holder that supports a coil spring is fixed to the inner peripheral side of a toothed belt that is installed between a drive pulley and a driven pulley, and a slot that is longer in the installation direction X than the main body-side screw hole is formed in the base of the spring holder. Therefore, when fixing the spring holder that supports the coil spring to the device main body, the position of the slot in the installation direction X formed in the base of the spring holder that is to be aligned with the main body-side screw hole can be selected, thereby enabling fine adjustment of the center distance between the drive pulley and the driven pulley (pulley center distance) up until just before assembling the belt mechanism (see FIG. 1).

[0071] The tension adjustment mechanism of Comparative Example 1 was configured so that the driven pulley and the device body were connected via a coil spring, and the belt tension could be adjusted by adjusting the distance between the pulley axes. More specifically, the configuration was based on the example disclosed in Patent Document 1 (JP Patent Publication No. 07-125369) (see Figures 1, 3, and 4 of Patent Document 1).

[0072] The tension adjustment mechanism of Comparative Example 2 had the same configuration as the above embodiment, except that the hole formed in the base of the spring holder was a round hole that matched the screw hole on the main body side. In other words, it was configured so that fine adjustment of the distance between the pulley axes could not be made immediately before assembling the belt mechanism (not shown).

[0073] [Materials used] Drive pulley and driven pulley: Polyphenylene sulfide resin (Durafide 6150T73 manufactured by Polyplastics Co., Ltd.) Driven pulley base: Polyacetal resin ("Bestal G" manufactured by Mitsuboshi Belting Co., Ltd.) Spring holder: Polyacetal resin ("Bestal G" manufactured by Mitsuboshi Belting Co., Ltd.)

[0074] [Manufacturing tension adjustment mechanisms] The drive pulley, driven pulley, driven pulley base, and spring holder were each manufactured by injection molding using the materials described above. The spring was a coil spring, and the spring wire was an oil-tempered spring wire with a circular cross section (compliant with JIS G 3560:1994).

[0075] [Tension adjustment mechanism dimensions] Driven pulley base: 120mm x 100mm Spring holder: 80mm x 20mm

[0076] [Belt mechanism] (toothed belt) Belt width: 10mm Tooth shape: H-shaped straight teeth (cross section is approximately semicircular) Tooth pitch: 3mm Tooth height: 1.3 mm Belt circumference: 999mm Rubber-like elastomer: chloroprene rubber composition Tensile body: E glass fiber, core diameter 0.35 mm

[0077] (Pulley layout) The belt mechanisms of Example 1 and Comparative Examples 1 and 2 all had a two-axis layout consisting of a drive pulley and a driven pulley with straight teeth, with the drive pulley's rotating shaft equipped with an axle load detector (load cell), and the driven pulley equipped with a tension adjustment mechanism for each test specimen. Number of teeth on drive pulley / pulley diameter (assuming core wire): 46 teeth / 43.927 mm Number of teeth on driven pulley / pulley diameter (assuming core wire): 46 teeth / 43.927 mm Speed ​​ratio: 1 The center distance was set to 430 mm as a reference value, and in Example 1 and Comparative Example 1, fine adjustment was made so that a predetermined belt tension was obtained. Belt installation tension: Calculated from the axial load detected by an axial load detector (load cell) connected to the rotating shaft of the drive pulley when the belt is stationary just before it starts running, and set to 1 N / mm width (1 N per 1 mm width of the belt).

[0078] [Assembling the belt mechanism] Example 1 Using the procedure described in the above embodiment (see "Assembly of belt mechanism 1 with tension adjustment mechanism 6" above), the tension adjustment mechanism of Example 1 was attached to the driven pulley in the manner shown in Figure 2, and the belt mechanism shown in Figure 1 was assembled.

[0079] (Comparative Example 1) The tension adjusting mechanism according to Comparative Example 1 was attached to a driven pulley, and a belt mechanism was assembled (see FIGS. 1, 3, and 4 of Patent Document 1). (1) The spring (tension spring) was connected to the spring fixing piece on the main body side and the spring fixing piece on the pulley side. (2) The driven pulley is fixed to the shaft and bolted together with the pulley side spring fixing piece, thereby integrating the driven pulley and tension adjustment mechanism. (3) With the driven pulley pulled toward the drive pulley and held stationary, the belt is wound around the drive pulley and driven pulley. By releasing the driven pulley from its stationary state, the driven pulley moves away from the drive pulley due to the tension of the spring, and the belt is given a specified tension, completing the assembly of the belt mechanism.

[0080] (Comparative Example 2) The tension adjustment mechanism according to Comparative Example 2 was attached to the driven pulley, and the belt mechanism was assembled. The assembly procedure for the belt mechanism of Comparative Example 2 was the same as that of Example 1, but because it was not possible to adjust the distance between the pulley axes during assembly, the belt tension did not reach the specified value, and variations occurred between individual units.

[0081] [Evaluation of tension adjustment mechanisms: items, methods, and criteria] For each test piece (Example 1, Comparative Examples 1 and 2), we examined the space (whether extra space was required to attach the tensioning member to the device body) and the assembly (whether it was possible to accommodate dimensional variations in the components of the belt mechanism) to determine whether a tension adjustment mechanism capable of solving the problem of the present application was obtained.

[0082] [Overhaul inspection] (Test Method) In order to determine the space available (whether or not extra space is required to attach the tensioning member to the device body), the tension adjustment mechanism (test specimen) was disassembled to check whether the spring (biasing member) was directly connected to the device body.

[0083] (Judgment criteria) If the spring is not directly connected to the device body and no space is required to attach the spring to the device body, it is evaluated as being possible to secure space for the tension adjustment mechanism and is rated as A. If the spring is directly connected to the device body and space is required to attach the spring to the device body, it is evaluated as not being possible to secure space for the tension adjustment mechanism, and a rating of b is given. From the viewpoint of suitability for practical use in this application (space availability for the tension adjustment mechanism), the tension adjustment mechanism rated "a" was deemed to be at the pass level.

[0084] [Assembly test] (Test Method) To determine the ease of assembly (whether it is possible to accommodate variations in the dimensions of the belt mechanism), we checked whether there was any variation in the belt tension (design value: 1 N / mm width) between individual units after assembling the belt mechanism.

[0085] (Judgment criteria) If the belt tension during assembly can be adjusted to 1 N / mm and there is no variation in the belt tension between individual parts after the belt mechanism is assembled, the belt mechanism is evaluated as being easy to assemble (able to accommodate dimensional variations in the belt mechanism's components) and is given an A rating. If it is not possible to adjust the belt tension during assembly and there is variation in the belt tension between individual units after the belt mechanism is assembled, it is evaluated as not being possible to ensure the ease of assembly of the belt mechanism (the ability to accommodate dimensional variations in the belt mechanism's component parts), and a grade of B is given. From the viewpoint of suitability for practical use in this application (assembly of the belt mechanism), the tension adjustment mechanism rated "a" was deemed to be at an acceptable level.

[0086] [Overall Judgment] The overall criteria for judging (ranking) a tension adjustment mechanism as one that can solve this problem were determined as follows, based on the results of the two test items (space efficiency and ease of assembly) mentioned above. Rank A: If all of the above test items were rated as "a," it was deemed to be completely satisfactory for practical use and was given the highest rank. Rank B: If even one of the above test items received a rating of b, the solution was deemed insufficient to resolve the issue and the solution was ranked as failing.

[0087] [Verification results and considerations] The verification results are shown in Table 1. [Table 1]

[0088] (Example 1, Comparative Examples 1 and 2) The tension adjustment mechanism of Example 1 was rated as A for space efficiency because the compression spring (biasing member) was not directly connected to the device body and no space was required to attach the compression spring to the device body.In addition, the distance between the pulley axes was adjustable and there was no individual variation in the belt tension after the belt mechanism was assembled, so it was also rated as A for ease of assembly.The overall rating was Rank A.

[0089] The tension adjustment mechanism of Comparative Example 1 was rated as A for ease of assembly because it was possible to adjust the distance between the pulley axes and there was no variation in the belt tension after the belt mechanism was assembled. However, since the tension spring (biasing member) was directly connected to the device main body and space was required to attach the tension spring to the device main body, it was rated as B for space efficiency, and the overall rating was Rank B.

[0090] The tension adjustment mechanism of Comparative Example 2 was rated as A for space efficiency because the compression spring (biasing member) was not directly connected to the device body and no space was required to attach the compression spring to the device body. However, since it was impossible to adjust the distance between the pulley axes and there was individual variation in the belt tension after the belt mechanism was assembled, it was rated as B for ease of assembly, and the overall rating was Rank B.

[0091] (Effects obtained) From the above verification results, it was confirmed that the tension adjustment mechanism of Example 1 addresses the problem of the present application, and that it is possible to obtain a tension adjustment mechanism that is space-saving and can apply a predetermined tension to a belt in response to dimensional variations in the components that make up the belt mechanism, in a belt mechanism provided with a moving body that moves back and forth in the belt mounting direction X, and in which the spring holder (support member) that supports the coil spring is fixed to the inner side of the toothed belt that is mounted between the drive pulley and the driven pulley, and the spring holder has a long hole that is longer in the mounting direction X than the screw hole on the main body side, and the screw is inserted through the long hole and threaded into the screw hole. [Explanation of symbols]

[0092] 1 Belt mechanism 2 drive pulley 3 driven pulley 4 Toothed belt 5. Mobile 6 Tension adjustment mechanism 61 Driven pulley base 611 Base side locking part 612 Pedestal side protrusion 613 Base 614A·614B Slider 62A·62B Mounting part 63 Coil spring 64 Spring holder (support member) 641 Support member side locking portion 642 Support member side protrusion 643 Base 644 long hole 65 Fastening screw 66 Anti-slip 9. Device body 91 Body side screw hole X Erection direction

Claims

1. A tension adjustment mechanism that keeps constant the tension of a toothed belt installed between a drive pulley and a driven pulley, a driven pulley base that rotatably supports the driven pulley; a mounting portion provided on a device body to which the tension adjustment mechanism is attached, and configured to slidably guide the driven pulley base in an installation direction, which is a direction connecting a drive shaft of the drive pulley on which the toothed belt is installed and a rotation shaft of the driven pulley; a biasing member that biases the driven pulley base in a direction away from the drive pulley; a support member fixed to an inner peripheral side of the toothed belt stretched between the drive pulley and the driven pulley, and supporting the biasing member; Equipped with A tension adjustment mechanism in which a long hole that is longer in the installation direction than the screw hole formed in the device main body is formed in the support member, and a screw is inserted through the long hole and threaded into the screw hole, thereby fixing the support member to the device main body.

2. the biasing member is a coil spring, the driven pulley base is provided with a base-side protrusion into which the coil spring is inserted, and a base-side locking portion connected to the base-side protrusion and locking one end of the coil spring, 2. The tension adjustment mechanism of claim 1, wherein the support member has a support member side protrusion that faces the base side protrusion in the installation direction and into which the coil spring is inserted, and a support member side locking portion that is connected to the support member side protrusion and locks the other end of the coil spring.

3. 3. The tension adjustment mechanism according to claim 2, wherein the base-side protrusion and the support member-side protrusion are formed to protrude in the installation direction so that the elastic force due to compression of the coil spring becomes a predetermined value when the opposing base-side protrusion and the support member-side protrusion are in contact.

4. The tension adjustment mechanism according to any one of claims 1 to 3, wherein an anti-slip surface is provided on at least one of the contact surface of the device body with the support member and the contact surface of the support member with the device body.

5. The tension adjustment mechanism according to claim 2 or 3, wherein the length of the base side protrusion in the installation direction is longer than the length of the support member side protrusion in the installation direction, or the length of the support member side protrusion in the installation direction is longer than the length of the base side protrusion in the installation direction.

Images