Testing device for ball screw devices

Abstract

The present invention provides a test apparatus for ball screw devices that can change the magnitude of the radial load during testing. [Solution] The test apparatus for a ball screw device comprises a support section, a first motor, and a load device. The load device comprises a movable part that can move in the axial direction, a reaction force generating mechanism that presses the movable part in a second direction when the movable part moves in a first direction, and a jig device interposed between the linear motion part and the movable part. The jig device comprises a first jig attached to the linear motion part and a second jig supported by the movable part. The first jig has a first opposing surface facing the first direction. The second jig has a second opposing surface facing the first opposing surface. One of the first and second opposing surfaces has a linear cross-sectional shape when cut along a virtual plane extending in the axial and orthogonal directions, and is inclined with respect to the orthogonal direction. The other of the first and second opposing surfaces has an arc-shaped cross-sectional shape when cut from the same direction as the direction in which the other surface was cut.

Description

Technical Field

[0001] The present disclosure relates to a test apparatus for a ball screw device.

Background Art

[0002] A ball screw device is a device that converts rotational motion into linear motion or converts linear motion into rotational motion. In order to confirm the operation of this ball screw device and evaluate its efficiency, a test apparatus for a ball screw device has been conventionally used. Further, as an example of a test apparatus for a ball screw device, the one in the following patent document can be cited. In the following, the test apparatus for a ball screw device may be simply referred to as a test apparatus.

[0003] The test apparatus in the following patent document includes an axial load mechanism that generates an axial load (hereinafter referred to as an axial load) and a radial load mechanism that generates a radial load (hereinafter referred to as a radial load). The axial load mechanism is disposed between two nuts of the axial load mechanism. The radial load mechanism includes a block disposed radially outside the axial load mechanism, a rail, a slider movable along the rail, and a spacer interposed between the block and the slider. Further, by replacing the spacers with different thicknesses, the magnitude of the radial load is changed.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Incidentally, ball screw devices are mounted on electric brake systems that press brake pads. When an electric brake system presses the brake pads, it receives an axial load opposite to the direction of pressure on the brake pads and a load in the direction of rotation of the brake pads. The load in the direction of rotation of the brake pads is converted into a radial load and transmitted to the ball screw device. Also, as the load pressing the brake pads increases, the radial load transmitted to the ball screw device increases. Thus, the radial load acting on the ball screw device is not constant.

[0006] On the other hand, with the above-mentioned test apparatus, the spacer cannot be changed during the test, and the magnitude of the radial load remains constant during the test. Therefore, it is not possible to conduct tests that simulate environments in which the magnitude of the radial load changes.

[0007] This disclosure is made in view of the above and aims to provide a test apparatus for a ball screw device that can change the magnitude of the radial load during testing. [Means for solving the problem]

[0008] To achieve the above objective, a test apparatus for a ball screw device according to one aspect of the present disclosure includes a support portion that rotatably supports one of the rotating parts of the ball screw device, the screw shaft and the nut, and linearly supports the other linear part; a first motor that generates torque to rotate the rotating part; and a load device that applies a load to the linear part. The direction parallel to the central axis of the screw shaft is defined as the axial direction. One of the axial directions is defined as the first direction. The other of the axial directions is defined as the second direction. The direction perpendicular to the central axis of the screw shaft is defined as the orthogonal direction. The load device includes a movable part arranged in the first direction relative to the linear part and movable in the axial direction; a reaction force generating mechanism connected to the movable part that increases the load applied to the movable part in the second direction as the amount of movement of the movable part in the first direction increases; and a jig device interposed between the linear part and the movable part. The jig device includes a first jig attached to the linear part and a second jig supported by the movable part. The first jig has a first opposing surface facing the first direction. The second jig has a second opposing surface facing the second direction and facing the first opposing surface. One of the first and second opposing surfaces has a straight cross-sectional shape when cut along a virtual plane extending in the axial direction and the orthogonal direction, and is inclined with respect to the orthogonal direction. The other of the first and second opposing surfaces has an arc-shaped cross-sectional shape when cut from the same direction as the direction in which the first surface was cut.

[0009] When a linear motion component moves in a first direction, it receives a load from the moving component via a jig device. Here, regarding the cross-sectional shape, if the first opposing surface is arc-shaped and the second opposing surface is inclined, the direction of the load acting from the second jig to the first jig is in the direction normal to the second opposing surface, and is inclined with respect to the axial direction. Therefore, both axial and radial loads act on the linear motion component. Similarly, even if the cross-sectional shape is inclined on the first opposing surface and arc-shaped on the second opposing surface, both axial and radial loads act on the linear motion component. Furthermore, as the amount of movement of the nut in the first direction increases, the reaction force generated by the reaction force generation mechanism also increases. Therefore, the load acting on the linear motion component increases, and the radial load increases. Thus, according to this disclosure, the magnitude of the radial load changes during testing.

[0010] Furthermore, in the ball screw device testing apparatus described above, the direction perpendicular to both the axial direction and the perpendicular direction is defined as the width direction. The other surface is a hemispherical surface, and the cross-sectional shape when cut in the width direction is arc-shaped.

[0011] According to the above configuration, the other surface makes point contact with the first surface.

[0012] Furthermore, in the ball screw device testing apparatus described above, the direction perpendicular to both the axial direction and the perpendicular direction is defined as the width direction. The other surface is a curved surface, and the cross-sectional shape when cut in the width direction is straight.

[0013] According to the above configuration, the other surface makes line contact with the other surface. Therefore, the surface pressure is smaller compared to the case of point contact.

[0014] Furthermore, in the ball screw device testing apparatus described above, the loading device includes a linear guide that supports the movable component so that it can move in the axial direction. The first opposing surface is the other surface. The second opposing surface is the first surface.

[0015] If one of the inclined surfaces tilts toward the radial load, the tilt angle of that surface becomes smaller, making it impossible to apply the predetermined radial load. For this reason, it is preferable to provide one surface on the side of the first and second jigs that is less prone to tilting. However, in a ball screw device to which the first jig is attached, there are gaps between the nut and the balls and between the balls and the screw shaft, making it easy for the linear motion components to tilt relative to the rotating member. Furthermore, if the support part supports the rotating component of the ball screw device with a bearing, there are gaps between the outer ring and the balls and between the balls and the inner ring of the bearing, making the entire ball screw device prone to tilting. On the other hand, according to the above configuration, the moving component that supports the second jig is supported by a linear guide and is less prone to tilting. Also, the inclined surface is formed on the second jig. Therefore, the situation in which one surface tilts toward the radial load and makes it impossible to apply the predetermined radial load is avoided.

[0016] Furthermore, in the ball screw device testing apparatus described above, the first opposing surface may be the one surface, and the second opposing surface may be the other surface.

[0017] Furthermore, in the ball screw device testing apparatus described above, the reaction force generating mechanism includes a support portion for a biasing portion arranged in the first direction relative to the moving part, and a biasing portion supported by the support portion for the biasing portion and biasing the moving part in the second direction.

[0018] According to the above configuration, when the amount of movement in the first direction by the linear motion component increases, the axial length of the biasing portion decreases, and the biasing force exerted by the biasing portion increases.

[0019] Furthermore, in the ball screw device testing apparatus described above, the reaction force generating mechanism comprises a second motor and a load-side ball screw device that operates using the torque generated by the second motor. The biasing support is supported so as to be movable in the axial direction and moves in the axial direction by the load-side ball screw device.

[0020] According to the above configuration, during testing, the support for the biasing part can be moved axially to change the magnitude of the biasing force of the biasing part.

Advantages of the Invention

[0021] According to the test device for the ball screw device of the present disclosure, the magnitude of the radial load can be changed during the test.

Brief Description of the Drawings

[0022] [Figure 1] FIG. 1 is a schematic view of the test device for the ball screw device of Embodiment 1 viewed from the horizontal direction. [Figure 2] FIG. 2 is a schematic view of the state during the test of the test device for the ball screw device of Embodiment 1 viewed from the horizontal direction. [Figure 3] FIG. 3 is a cross-sectional view of the jig device of Embodiment 1 and its vicinity cut in the vertical direction from the central axis. [Figure 4] FIG. 4 is a perspective view of the first jig of Embodiment 1 viewed obliquely from the first direction. [Figure 5] FIG. 5 is a perspective view of the second jig of Embodiment 1 viewed obliquely from the second direction. [Figure 6] FIG. 6 is a cross-sectional view of the test device for the ball screw device of Embodiment 2, in which the jig device and its vicinity are cut in the vertical direction from the central axis. [Figure 7] FIG. 7 is a schematic view of the ball screw device tilted in the test device for the ball screw device of Embodiment 1. [Figure 8] FIG. 8 is a schematic view of the ball screw device tilted in the test device for the ball screw device of Embodiment 2. [Figure 9] FIG. 9 is a schematic view of the test device for the ball screw device of Embodiment 3 viewed from the horizontal direction. [Figure 10] FIG. 10 is a schematic view of the test device for the ball screw device of Embodiment 4 with the jig device and its vicinity enlarged and viewed from the horizontal direction.

Modes for Carrying Out the Invention

[0023] The forms for implementing this disclosure will be described in detail with reference to the drawings. This disclosure is not limited by the contents described below. Furthermore, the components described below include those that are readily conceivable to a person skilled in the art, and those that are substantially the same. In addition, the components described below can be combined as appropriate.

[0024] (Embodiment 1) Figure 1 is a schematic diagram of the test apparatus for the ball screw device of Embodiment 1, viewed from the horizontal direction. Before describing the test apparatus 100 for the ball screw device of Embodiment 1, the ball screw device 110 will be briefly described. The ball screw device 110 comprises a screw shaft 111, a nut 112 into which the screw shaft 111 is inserted, and a plurality of balls (not shown) arranged between the screw shaft 111 and the nut 112. Hereinafter, the direction parallel to the central axis O of the screw shaft 111 will be referred to as the axial direction.

[0025] In the ball screw device 110, torque is transmitted to one of the components, the screw shaft 111 and the nut 112, causing that component (which may be referred to as the rotating component) to rotate. The other component of the screw shaft 111 and the nut 112 (which may be referred to as the linear motion component) then moves linearly in the axial direction (which may be referred to as linear motion). In the ball screw device test apparatus 100 of Embodiment 1, the screw shaft 111 corresponds to the rotating component, and the nut 112 corresponds to the linear motion component.

[0026] Next, the test apparatus 100 for ball screw devices will be described. In the following description, the test apparatus 100 for ball screw devices will be described using the ball screw device 110 to be tested already installed as an example.

[0027] As shown in Figure 1, the ball screw device test apparatus 100 of Embodiment 1 comprises a base 101, a support part 1 for supporting the ball screw device 110 to be tested, an actuator 2 for operating the ball screw device 110, and a load device 3 for applying a load to the ball screw device 110.

[0028] The base 101 of this embodiment extends horizontally. The mounting surface 102 of the base 101 faces upward Y1 in the vertical direction. Therefore, in the following description, the direction that the mounting surface 102 of the base 101 faces will be referred to as upward Y1, and the direction opposite to the direction that the mounting surface 102 faces will be referred to as downward Y2.

[0029] In this embodiment, the base 101 is horizontal, but the present disclosure also allows the base 101 to be inclined with respect to the horizontal direction, or the normal to the base 101 to extend in the horizontal direction, and there are no particular restrictions on the orientation of the base 101.

[0030] The support part 1 rotatably supports the screw shaft 111 and supports the nut 112 so that it can move in the axial direction. The support part 1 also supports the ball screw device 110 so that the central axis O of the screw shaft 111 is horizontal.

[0031] A load device 3 is positioned on one side of the axial direction when viewed from the support part 1 (screw shaft 111), and an actuator 2 is positioned on the other side of the axial direction. Hereinafter, the direction in which the load device 3 is positioned when viewed from the support part 1 will be referred to as the first direction X1, and the direction in which the actuator 2 is positioned when viewed from the support part 1 will be referred to as the second direction X2.

[0032] The actuator 2 comprises a first motor 20 and a torque sensor 23 arranged sequentially from the second direction X2. The first motor 20 generates torque to operate the ball screw device 110. The first motor 20 has a main body 21 and an output shaft 22.

[0033] The torque sensor 23 is positioned between the support unit 1 (ball screw device 110) and the first motor 20, and measures the torque transmitted to the ball screw device 110. The torque sensor 23 has a main body 24, a first shaft 25 extending from the main body 24 in a second direction X2, and a second shaft 26 extending from the main body 24 in a first direction X1.

[0034] The output shaft 22 and the first shaft 25 are connected by a coupling 90. The second shaft 26 and the screw shaft 111 are connected by a coupling 91.

[0035] As described above, when the first motor 20 is driven, torque is transmitted to the screw shaft 111 via the torque sensor 23. Then the screw shaft 111 rotates, and the nut 112 moves in the axial direction.

[0036] The load device 3 comprises a reaction force generating mechanism 10, a load cell 47, a moving component 50, and a jig device 60, all arranged in order from the first direction X1.

[0037] The reaction force generating mechanism 10 applies a reaction force to the moving part 50 by pressing it in the second direction X2 when the moving part 50 moves in the first direction X1. This reaction force generating mechanism 10 allows an axial load to be applied to the nut 112 moving in the first direction X1 during testing of the ball screw device 110. The reaction force generating mechanism 10 of this embodiment includes a second motor 30, a load-side ball screw device 33, a biasing support part 37, and a biasing part 45, all arranged in order from the first direction X1.

[0038] The second motor 30 generates power to adjust the axial length of the biasing unit 45. The second motor 30 comprises a body 31 and an output shaft 32.

[0039] The load-side ball screw device 33 converts the rotational motion generated by the second motor 30 into linear motion. The load-side ball screw device 33 comprises a screw shaft 34, a nut 35, and a plurality of balls (not shown). The base 101 is also provided with a load-side support portion 36 that supports the load-side ball screw device 33. The load-side support portion 36 rotatably supports the screw shaft 34 and supports the nut 35 so that it can move in the axial direction. The screw shaft 34 is connected to the output shaft 32 of the second motor 30 by a coupling 92. In this disclosure, the nut 35 may rotate and the screw shaft 34 may move in the axial direction.

[0040] The biasing support section 37 comprises a main body 38 and a rod 39 supported by the main body 38 so as to be movable in the axial direction. The rod 39 extends from the main body 38 in a second direction X2. A flange 40 is provided at the end of the rod 39 in the second direction X2.

[0041] The biasing part 45 is a component that exerts a biasing force. The biasing part 45 is positioned between the end face of the main body 38 in the second direction X2 and the flange 40, and biases the flange 40 in the second direction X2. Specific examples of the biasing part 45 include coil springs and disc springs. In the case of disc springs, multiple disc springs may be arranged in the axial direction.

[0042] In this embodiment, the main body 38 is supported so as to be movable in the axial direction by a linear guide 41 fixed to the base 101. The linear guide 41 has a rail 42 that extends in the axial direction and a slider 43 that is movable in the axial direction along the rail 42. A nut 35 of the load-side ball screw device 33 is connected to the end of the main body 38 in the first direction X1.

[0043] The load cell 47 measures the axial load. The load cell 47 is fixed to the flange 40 of the biasing support 37 in the second direction X2.

[0044] The movable component 50 is positioned in a first direction X1 relative to the nut 112 of the ball screw device 110. The movable component 50 is connected to the load cell 47 in a second direction X2.

[0045] The movable component 50 is supported so as to be movable in the axial direction by a linear guide 51 fixed to the base 101. The linear guide 51 has a rail 52 that extends in the axial direction and a slider 53 that is movable in the axial direction along the rail 52. In addition, preload is applied to the linear guide 51 in this embodiment so that the movable component 50 is less prone to rattling.

[0046] The jig device 60 includes a first jig 61 attached to the nut 112 and a second jig 71 supported by the movable part 50. Details of the jig device 60 will be described later.

[0047] Next, we will explain how to use the ball screw device testing apparatus 100.

[0048] Figure 2 is a schematic diagram of the test apparatus for the ball screw device of Embodiment 1, viewed from the horizontal during testing. In this description, the state before the start of the test is assumed to be that the first jig 61 and the second jig 71 are already in contact, as shown in Figure 2. Furthermore, with the first jig 61 and the second jig 71 in contact, the axial length of the biasing part 45 is assumed to be smaller than its natural length, and a biasing force is being exerted. In other words, the second jig 71 presses the first jig 61 in the second direction X2, and a load (see arrow F1 in Figure 2) is applied to the nut 112 even before the first motor 20 starts driving.

[0049] As shown in Figure 2, the test first drives the first motor 20 to move the nut 112 in the first direction X1 (see arrow A1 in Figure 2). The nut 112 then moves in the first direction X1 while receiving a load from the load device 3 in the second direction X2 (see arrow F1 in Figure 2).

[0050] Furthermore, the movement of the nut 112 causes the movable part 50 to move in the first direction X1 (see arrow A2 in Figure 2). Consequently, the flange 40 also moves in the first direction X1 (see arrow A3 in Figure 2). As a result, the axial length of the biasing part 45 decreases, and the biasing force exerted by the biasing part 45 on the flange 40 in the second direction X2 (see arrow F2 in Figure 2) increases. This increases the load on the nut 112 being pressed in the second direction X2. Therefore, as the amount of movement of the nut 112 in the first direction X1 increases, the load in the second direction X2 acting from the load device 3 (see arrow F1 in Figure 2) increases.

[0051] Furthermore, during the test, the torque sensor 23 measures the torque transmitted to the screw shaft 111 of the ball screw device 110. The load cell 47 measures the axial load acting on the moving part 50. The efficiency of the ball screw device 110 is then calculated from the data measured by the torque sensor 23 and the load cell 47. This allows for the evaluation of the characteristics of the ball screw device 110.

[0052] Furthermore, when the second motor 30 is driven during the test, the main body 38 of the biasing support 37 moves in the axial direction. If the main body 38 moves in the second direction X2 (see arrow A4 in Figure 2), the axial length of the biasing part 45 decreases, and the biasing force of the biasing part 45 (see arrow F2 in Figure 2) increases. On the other hand, if the main body 38 moves in the first direction X1 (see arrow A5 in Figure 2), the axial length of the biasing part 45 increases, and the biasing force of the biasing part 45 (see arrow F2 in Figure 2) decreases. From the above, it can be seen that, according to this embodiment, the magnitude of the reaction force generated by the reaction force generating mechanism 10 can be changed during the test. In other words, the magnitude of the load acting on the nut 112 (see arrow F1 in Figure 2) can be changed.

[0053] Next, the details of the jig device 60 will be described. In the following description, the direction perpendicular to the axial direction and the vertical direction will be referred to as the width direction Z (see Figures 4 and 5).

[0054] Figure 3 is a cross-sectional view of the jig device of Embodiment 1 and its vicinity, cut vertically from the central axis. As shown in Figure 3, the support portion 1 of this embodiment has a bearing 4 that rotatably supports the screw shaft 111. The support portion 1 also has a cylindrical portion 5 located radially outside the nut 112. A groove (not shown) extending in the axial direction is formed in this cylindrical portion 5. An anti-rotation mechanism (not shown) that fits into the groove is provided on the outer circumferential surface of the nut 112. Therefore, the nut 112 is supported by the support portion 1 in a way that prevents rotation and allows movement in the axial direction.

[0055] As shown in Figure 3, the first jig 61 comprises a first jig body 62 and a first fitting portion 63 that protrudes from the first jig body 62 in a second direction X2.

[0056] Figure 4 is a perspective view of the first jig of Embodiment 1, viewed obliquely from a first direction. The first jig body 62 extends in the vertical direction and the width direction Z, and is formed in a plate shape. The first jig body 62 has a rectangular shape when viewed from the axial direction. The first jig body 62 has a first opposing surface 64 facing the first direction X1.

[0057] The first opposing surface 64 is formed in an arc shape when viewed from the width direction, and is a curved surface. Therefore, the cross-sectional shape when the first opposing surface 64 is cut along a virtual plane (not shown) extending in the axial and vertical directions is also arc-shaped (see Figure 3). Although not specifically shown, the cross-sectional shape when the first opposing surface 64 is cut in the width direction Z is straight.

[0058] The first fitting portion 63 is formed in an annular shape. The first fitting portion 63 is fitted to the inner circumference of the nut 112. Therefore, the first jig 61 is detachably attached to the nut 112. The first fitting portion 63 may be fitted to the nut 112 either as a clearance fit or as a tight fit. During the test, the first jig 61 receives a load (load in the second direction X2) from the load device 3. Therefore, even if the first fitting portion 63 is fitted to the nut 112 as a clearance fit, it will not fall off the nut 112.

[0059] As shown in Figure 3, the second jig 71 comprises a second jig body 72, a second fitting portion 73 protruding from the second jig body 72 in a first direction X1, and a protruding portion 74 protruding from the second jig body 72 in a second direction X2.

[0060] Figure 5 is a perspective view of the second jig of Embodiment 1, viewed obliquely from a second direction. As shown in Figure 5, the second jig body 72 extends in the vertical direction and the width direction Z, and is formed in a plate shape. The second jig body 72 has a rectangular shape when viewed from the axial direction.

[0061] The protruding portion 74 has a rectangular shape when viewed from the axial direction. The protruding portion 74 has a second opposing surface 75 facing the second direction X2.

[0062] The second opposing surface 75 is formed as a plane. Furthermore, the second opposing surface 75 protrudes in the second direction X2 as it extends downward Y2. Therefore, as shown in Figure 3, the cross-sectional shape when the second opposing surface 75 is cut along a virtual plane extending in the axial and vertical directions is linear and inclined with respect to the vertical direction. Also, the virtual line K1 in Figure 3 is the normal to the second opposing surface 75.

[0063] The second fitting portion 73 is fitted into a recess 55 formed on the end face of the movable part 50 in the second direction X2. The second fitting portion 73 is fitted into the recess 55. Therefore, the second fitting portion 73 is detachably attached to the movable part 50. The second fitting portion 73 may be fitted into the recess 55 either with a gap fit or with a tight fit. During the test, the second jig 71 receives a load from the nut 112 in the first direction X1. Therefore, the second fitting portion 73 will not fall off even if it is fitted into the recess 55 with a gap fit.

[0064] As described above, with the jig device 60, as shown in Figure 3, the first opposing surface 64 of the first jig 61 and the second opposing surface 75 of the second jig 71 are arranged to face each other and come into contact with each other from the axial direction during the test. Furthermore, the direction of the load F2 acting from the second opposing surface 75 to the first opposing surface 64 is parallel to the normal direction (imaginary line K1) of the second opposing surface 75. When this load F2 is divided into components, it includes an axial load in the second direction X2 (axial direction) and a radial load in the upward direction Y1 (vertical direction).

[0065] Furthermore, as the amount of movement of the nut 112 in the first direction X1 increases, the reaction force generated by the reaction force generating mechanism 10 increases, and the load F2 acting on the nut 112 increases. In other words, both the axial load and radial load acting on the nut 112 increase. Thus, according to this embodiment, the radial load acting on the nut 112 can be increased during testing.

[0066] Furthermore, in this embodiment, the magnitude of the biasing force of the biasing unit 45 can be changed by driving the second motor 30 during the test, that is, the magnitude of the load F2 acting on the nut 112 can be changed. In this way, the magnitude of the radial load acting on the nut 112 can also be changed during the test by driving the second motor 30.

[0067] Furthermore, according to Embodiment 1, the jig device 60 is formed to be detachably attached to the nut 112 and the movable part 50. Therefore, multiple second jigs 71 with different inclination angles of the second opposing surface 75 may be prepared to change the ratio of axial load to radial load.

[0068] Although Embodiment 1 has been described above, this disclosure is not limited to the example described above. For example, a reduction gear may be further provided to increase the torque of the first motor 20 and the second motor 30. Also, if the test is not for testing efficiency but for confirming operation, such as whether abnormal noise occurs, or for evaluating durability, the ball screw device test apparatus 100 does not need to be equipped with a torque sensor 23 or a load cell 47. Furthermore, a temperature sensor or the like may be added to the ball screw device test apparatus 100 to measure the temperature of the ball screw device 110 during testing. In addition, although the actuator 2 is arranged in the second direction X2 with respect to the support part 1, it may be arranged in the width direction Z and the torque may be transmitted to the screw shaft 111 by a pulley or the like. In this way, the configuration of the ball screw device test apparatus 100 may be changed as needed.

[0069] Furthermore, regarding the jig device 60 of Embodiment 1, the first jig 61 and the second jig 71 have a rectangular shape when viewed from the axial direction (see Figures 4 and 5), but they may also be circular, and there are no particular restrictions on the shape when viewed from the axial direction.

[0070] Furthermore, it is preferable to set the inclination angle of the second opposing surface 75 with respect to the orthogonal direction (up and down direction in Embodiment 1) to a range of 0.5 deg to 9 deg. Also, it is preferable that the radius of curvature of the first opposing surface 64 be 10 mm or more in order to reduce surface pressure. In addition, because the second opposing surface 75 is inclined, the point of contact with the first opposing surface 64 is shifted in the direction orthogonal to the central axis O (downward Y2 in Embodiment 1). As the point of contact between the second opposing surface 75 and the first opposing surface 64 moves away from the central axis O, errors are likely to occur in the axial load and radial load input to the nut 112. Furthermore, in order to reduce the moment load received by the ball screw device, it is preferable that the point of contact between the second opposing surface 75 and the first opposing surface 64 be no more than four times the outer diameter of the screw shaft 111 from the center O1 of the ball screw device 110.

[0071] Furthermore, while the second opposing surface 75 in Embodiment 1 protrudes in the second direction X2 as it moves downward Y2, the present disclosure may also have the second opposing surface 75 protrude in the second direction X2 as it moves upward Y1. Alternatively, the second opposing surface 75 may protrude in the second direction X2 as it moves from one side of the width direction Z to the other. Thus, the second opposing surface 75 in the present disclosure only needs to have a linear cross-sectional shape along a virtual plane extending in the axial and orthogonal directions, and be inclined in the orthogonal direction.

[0072] Furthermore, while the first opposing surface 64 in Embodiment 1 has an arc-shaped curved surface when viewed from the width direction Y, the present disclosure may also show that the first opposing surface 64 is a hemisphere. If the first opposing surface 64 is a hemisphere, the cross-sectional shape when cut in the width direction will also be arc-shaped. In the present disclosure, the first opposing surface 64 only needs to have an arc-shaped cross-sectional shape when cut in the same direction as the cross-sectional view of the second opposing surface 75 (a cross-sectional view showing the state in which the second opposing surface 75 is straight and inclined in the orthogonal direction).

[0073] In Embodiment 1, the first opposing surface 64 is a curved surface and makes line contact with the second opposing surface 75. Therefore, the surface pressure acting on the first opposing surface 64 and the second opposing surface 75 is greater than in the case of surface contact. Furthermore, as mentioned above, if the first opposing surface 64 is a hemispherical surface, the first opposing surface 64 makes point contact with the second opposing surface 75. Therefore, the surface pressure acting on the first opposing surface 64 and the second opposing surface 75 becomes even greater. Thus, the structure has a large surface pressure acting on the first opposing surface 64 and the second opposing surface 75. Therefore, in order to avoid deformation or damage to the first jig 61 and the second jig 71, this disclosure may provide a hard protective film on at least one of the first opposing surface 64 and the second opposing surface 75. In addition, in order to avoid deformation, etc., the hardness of the first jig 61 is preferably HV300 or higher (Vickers hardness). The hardness of the second jig 71 is preferably HV300 or higher (Vickers hardness).

[0074] Furthermore, regarding the cross-sectional shape cut in an orthogonal direction perpendicular to the axial direction (up and down in Embodiment 1), in Embodiment 1, the first opposing surface 64 is arc-shaped and the second opposing surface 75 is linear and inclined in the orthogonal direction, but this disclosure is not limited to this. This disclosure is acceptable as long as one of the first opposing surface 64 and the second opposing surface 75 is linear and inclined in the orthogonal direction, and the other surface is arc-shaped. In other words, as will be explained in Embodiment 2 below, this disclosure may have an arc-shaped second opposing surface 75 and a linear and inclined first opposing surface 64. The following description will focus on the differences from Embodiment 1.

[0075] (Embodiment 2) Figure 6 is a cross-sectional view of the ball screw device testing apparatus of Embodiment 2, showing the jig device and its vicinity cut vertically from the central axis. As shown in Figure 6, the ball screw device testing apparatus 100A of Embodiment 2 differs from Embodiment 1 in that the shape of the first opposing surface 64A of the first jig 61A and the shape of the second opposing surface 75A of the second jig 71A are swapped.

[0076] The first opposing surface 64A is formed as a plane. The first opposing surface 64A protrudes in the first direction X1 as it moves downward Y2. Therefore, the cross-sectional shape when the first opposing surface 64A is cut in the vertical direction is linear and inclined with respect to the vertical direction. The dashed line K2 in Figure 6 is the normal to the first opposing surface 64A.

[0077] The second opposing surface 75A is a curved surface formed in an arc shape when viewed from the width direction. Therefore, the cross-sectional shape when the second opposing surface 75A is cut in the vertical direction is also an arc shape.

[0078] As described above, according to Embodiment 2, the direction of the load F2 acting from the second jig 71A to the first jig 61A is parallel to the normal direction of the first opposing surface 64A (see dashed line K2 in Figure 6). When this load F2 is divided into components, it includes an axial load in the second direction X2 (axial direction) and a radial load downward Y2 (vertical direction). Therefore, similar to Embodiment 1, the magnitude of the radial load acting on the nut 112 can be changed during the test.

[0079] Embodiment 2 has been described above. Incidentally, the bearing 4 (see Figures 3 and 6) supporting the ball screw device 110 has gaps between the outer ring and the balls, and between the balls and the inner ring. Therefore, there is a possibility that the entire ball screw device 110 may tilt when a radial load is applied during testing. The pivot point P (see Figures 3 and 6) when the ball screw device 110 tilts is the center of the bearing 4 of the support part 1. In addition, the ball screw device 110 has gaps between the nut 112 and the balls, and between the balls and the screw shaft 111, so there is a possibility that the nut 112 may tilt relative to the screw shaft 111. If the entire ball screw device 110 or only the nut 112 tilts in this way, the first jig 61 will also tilt. Below, the effects of Embodiment 1 and Embodiment 2 will be compared and explained in the case where such tilting occurs. Furthermore, in the following explanation, the case in which the ball screw device 110 tilts around the pivot point P will be given as an example.

[0080] Figure 7 is a schematic diagram of the test apparatus for a ball screw device of Embodiment 1 when the ball screw device is tilted. As shown in Figure 7, in Embodiment 1, the ball screw device 110 tilts such that the nut 112 moves upward Y1 around the fulcrum P (see arrow B1 in Figure 7). Therefore, the arc-shaped first opposing surface 64 also tilts. On the other hand, the tilt angle of the second opposing surface 75 does not change. In other words, since the normal direction of the second opposing surface 75 (see dashed line K1) does not change, the direction of the load F3 also does not change.

[0081] In Embodiment 1, the movable component 50 is supported by a linear guide 51. Therefore, the possibility of the movable component 50 (second opposing surface 75) tilting and changing the direction of the load F3 is extremely low.

[0082] Figure 8 is a schematic diagram of the test apparatus for a ball screw device of Embodiment 2 when the ball screw device is tilted. Note that the dashed line Q in Figure 8 indicates the position of the first jig 61A when the ball screw device 110 is not tilted. As shown in Figure 8, the ball screw device 110 of Embodiment 2 tilts such that the nut 112 moves downward Y2 around the fulcrum P. Therefore, the tilt angle of the first opposing surface 64A changes, the normal direction of the first opposing surface 64A (see dashed line K2) changes, and the direction of the load F4 changes. The tilt angle of the first opposing surface 64A after the ball screw device 110 is tilted is smaller than before the ball screw device 110 is tilted (see dashed line Q in Figure 8). In other words, in Embodiment 2, the proportion of the load F4 that is divided into radial loads becomes smaller.

[0083] From the above, according to Embodiment 1, even if the ball screw device 110 is tilted, the magnitude of the radial load acting on the nut 112 can be set to a predetermined value. On the other hand, according to Embodiment 2, if the ball screw device 110 is tilted, the radial load acting on the nut 112 will be smaller than the predetermined value. Therefore, it may not be possible to obtain proper test results. In other words, when using the jig device 60A of Embodiment 2, it is necessary to configure the support part 1 so that the ball screw device 110 does not tilt. From the above, Embodiment 1 is superior to Embodiment 2 in that it eliminates the need to devise a way to prevent the ball screw device 110 from falling over.

[0084] As described above, when the ball screw device 110 or nut 112 tilts, the first opposing surfaces 64, 64A and the second opposing surfaces 75, 75A slide against each other. Therefore, in this disclosure, grease may be applied to at least one of the first opposing surfaces 64, 64A and the second opposing surfaces 75, 75A.

[0085] The effects and advantages of Embodiment 1 and Embodiment 2 have now been compared.

[0086] Furthermore, while the reaction force generating mechanism 10 of Embodiment 1 includes a second motor 30 and a load-side ball screw device 33 to move the main body 38 of the biasing support 37 in the axial direction, this disclosure also allows for the movement of the main body 38 in the axial direction using a hydraulic actuator or an air actuator instead of the second motor 30 and the load-side ball screw device 33.

[0087] Furthermore, in the above-described embodiment, the reaction force generating mechanism 10 is configured such that the main body 38 of the biasing support 37 moves in the axial direction. However, in this disclosure, the main body 38 may be fixed. Embodiment 3, in which the main body 38 is fixed, will be described below.

[0088] (Embodiment 3) Figure 9 is a schematic diagram of the ball screw device testing apparatus of Embodiment 3, viewed from the horizontal direction. As shown in Figure 9, the ball screw device testing apparatus 100B of Embodiment 3 differs from Embodiment 1 in that the reaction force generating mechanism 10B does not include a second motor 30, a load-side ball screw device 33, and a linear guide 41. In other words, it differs from Embodiment 1 in that the main body of the support part for the biasing part is fixed to the base 101. According to this Embodiment 3, it is not possible to intentionally increase or decrease the biasing force exerted by the biasing part 45 during the test. However, as with the other embodiments, as the amount of movement of the nut 112 in the first direction X1 increases, the magnitude of the radial load acting on the nut 112 increases, and the radial load changes.

[0089] Embodiment 3 has been described above. In the embodiment described above, the screw shaft 111 is a rotating part and the nut 112 is a linear motion part, but in this disclosure, as will be described in Embodiment 4 below, the nut 112 may be a rotating part and the screw shaft 111 may be a linear motion part.

[0090] (Embodiment 4) Figure 10 is a schematic diagram of the ball screw device testing apparatus of Embodiment 4, showing an enlarged view of the jig and its vicinity from the horizontal direction. As shown in Figure 10, the support portion 1C of the ball screw device testing apparatus 100C of Embodiment 4 differs from Embodiment 1 in that it supports the screw shaft 111 so that it is immobile but movable in the axial direction, and the nut 112 is rotatably supported by a bearing 4C. In addition, a recess 113 is formed on the end face of the screw shaft 111 in the first direction X1, recessed in the second direction X2. The first fitting portion 63 of the first jig 61 is fitted into the recess 113. Even in this Embodiment 4, as with the other embodiments, the magnitude of the radial load acting on the screw shaft 111 can be changed during testing.

[0091] Although each embodiment has been described above, the ball screw device tested with the ball screw device test apparatus of this disclosure may be a ball screw device other than a ball screw device mounted on an electric brake device, and the type and size of the ball screw device are not particularly limited. Also, in the description of the usage method of Embodiment 1, the first jig 61 and the second jig 71 were described as being in contact at the start of the test, but in this disclosure, the first jig 61 and the second jig 71 may not be in contact at the start of the test. Furthermore, although the movable part 50 in this embodiment is supported by a linear guide 51, this disclosure may not have a linear guide 51. In this case, the movable part 50 is supported so as to be movable in the axial direction by a biasing support part 37 via a load cell 47.

[0092] Furthermore, this disclosure may also be a combination of the following configurations. (1) A support part that rotatably supports one of the rotating parts of a ball screw device, the screw shaft and the nut, and linearly supports the other linear part, A first motor that generates torque to rotate the aforementioned rotating part, A loading device that applies a load to the aforementioned linear motion component, Equipped with, The direction parallel to the central axis of the screw shaft is defined as the axial direction. One of the axial directions is designated as the first direction, The other axial direction is designated as the second direction, The direction perpendicular to the central axis of the screw shaft is defined as the orthogonal direction. The aforementioned load device is A movable component is positioned in the first direction relative to the linear motion component and is movable in the axial direction, A reaction force generating mechanism connected to the moving part increases the load applied to the moving part in the second direction as the amount of movement of the moving part in the first direction increases, A jig device interposed between the linear motion component and the moving component, Equipped with, The aforementioned jig device is A first jig attached to the aforementioned linear motion component, A second jig supported by the aforementioned moving part, Equipped with, The first jig has a first opposing surface facing the first direction, The second jig has a second opposing surface that faces the second direction and faces the first opposing surface, One of the first opposing surface and the second opposing surface has a cross-sectional shape that is straight when cut along a virtual plane extending in the axial direction and the orthogonal direction, and is inclined with respect to the orthogonal direction. The other of the two opposing surfaces, the first and second, has an arc-shaped cross-section when cut from the same direction as the first surface. Testing device for ball screw devices. (2) The direction perpendicular to the axial direction and the perpendicular direction is defined as the width direction. The other surface is a hemisphere, and its cross-sectional shape when cut in the width direction is arc-shaped. (1) Test apparatus for ball screw devices as described above. (3) The direction perpendicular to the axial direction and the perpendicular direction is defined as the width direction. The other surface is a curved surface, and the cross-sectional shape when cut in the width direction is straight. (1) Test apparatus for ball screw devices as described above. (4) The load device includes a linear guide that supports the movable component so that it can move in the axial direction, The first opposing surface is the other surface, The second opposing surface is the one surface mentioned above. A test apparatus for a ball screw device as described in any one of (1) to (3). (5) The first opposing surface is the one surface, The second opposing surface is the other surface. A test apparatus for a ball screw device as described in any one of (1) to (3). (6) The reaction force generating mechanism is A support portion for biasing the moving part is arranged in the first direction with respect to the moving part, A biasing part supported by the biasing part support and biasing the moving part in the second direction, It is equipped with A test apparatus for a ball screw device as described in any one of (1) to (5). (7) The reaction force generating mechanism is The second motor and A load-side ball screw device that operates using the torque generated by the second motor, Equipped with, The support portion for the biasing portion is supported so as to be movable in the axial direction and is moved in the axial direction by the load-side ball screw device. (6) Test apparatus for ball screw devices as described above. [Explanation of symbols]

[0093] 1, 1C support part 2 Actuator 3, 3B load device 10. Reaction force generation mechanism 20 First motor 23 Torque Sensor 30 Second motor 33 Load-side ball screw device 37 Support part for biasing part 41, 51 Linear guide 45. Energizing part 47 Load Cells 50 movable parts 60, 60A Fixture Device 61, 61A First jig 62. First Jig Body 63 First mating section 64, 64A First opposing surface 71, 71A Second jig 72 Second Jig Body 73 Second mating section 74 Protrusion 75, 75A Second opposing surface Testing device for ball screw devices: 100, 100A, 100B, 100C 101 Base 110 Ball screw device 111 Screw shaft 112 Nut

Claims

1. A support part that rotatably supports one of the rotating parts of a ball screw device, the screw shaft and the nut, and linearly supports the other linear part, A first motor that generates torque to rotate the aforementioned rotating part, A loading device that applies a load to the aforementioned linear motion component, Equipped with, The direction parallel to the central axis of the screw shaft is defined as the axial direction. One of the axial directions is designated as the first direction, The other direction in the axial direction is designated as the second direction. The direction perpendicular to the central axis of the screw shaft is defined as the orthogonal direction. The aforementioned load device is A movable component is positioned in the first direction relative to the linear motion component and is movable in the axial direction, A reaction force generating mechanism connected to the moving part increases the load applied to the moving part in the second direction as the amount of movement of the moving part in the first direction increases, A jig device interposed between the linear motion component and the moving component, Equipped with, The aforementioned jig device is A first jig attached to the aforementioned linear motion component, A second jig supported by the aforementioned moving part, Equipped with, The first jig has a first opposing surface facing the first direction, The second jig has a second opposing surface that faces the second direction and faces the first opposing surface, One of the first opposing surface and the second opposing surface has a cross-sectional shape that is straight when cut along a virtual plane extending in the axial direction and the orthogonal direction, and is inclined with respect to the orthogonal direction. The other of the two opposing surfaces, the first and second, has an arc-shaped cross-section when cut from the same direction as the first surface. Testing device for ball screw devices.

2. The direction perpendicular to the axial direction and the perpendicular direction is defined as the width direction. The other surface is a hemisphere, and its cross-sectional shape when cut in the width direction is arc-shaped. A test apparatus for a ball screw device according to claim 1.

3. The direction perpendicular to the axial direction and the perpendicular direction is defined as the width direction. The other surface is a curved surface, and the cross-sectional shape when cut in the width direction is straight. A test apparatus for a ball screw device according to claim 1.

4. The load device includes a linear guide that supports the movable component so that it can move in the axial direction, The first opposing surface is the other surface, The second opposing surface is the one surface mentioned above. A test apparatus for a ball screw device according to any one of claims 1 to 3.

5. The first opposing surface is the one surface, The second opposing surface is the other surface. A test apparatus for a ball screw device according to any one of claims 1 to 3.

6. The reaction force generating mechanism is A support portion for biasing the moving part is arranged in the first direction with respect to the moving part, A biasing part supported by the biasing part support and biasing the moving part in the second direction, It is equipped with A test apparatus for a ball screw device according to claim 1.

7. The reaction force generating mechanism is The second motor and A load-side ball screw device that operates using the torque generated by the second motor, Equipped with, The support portion for the biasing portion is supported so as to be movable in the axial direction and is moved in the axial direction by the load-side ball screw device. Test apparatus for ball screw device according to claim 6.

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