JP7704715B2 - Load Sensor - Google Patents

Description

The present invention relates to a load sensor.

In driving devices such as electric parking brake devices, load sensors are used to detect the driving load of the driven object. As disclosed in Patent Document 1, for example, the load sensor includes a magnet and a Hall IC. The load sensor detects the driving load of the driven object based on the positional relationship between the magnet and the Hall IC.

JP 2020-67427 A

However, in a drive device having multiple components, play between the components when the drive device is in operation or misalignment of the mounting positions of the components can cause the Hall IC to shift position relative to the magnet, resulting in a decrease in detection accuracy.

The present invention aims to provide a load sensor that can suppress a decrease in detection accuracy.

The load sensor of the present invention is a load sensor that detects a load equal to or greater than a predetermined value being applied to a moving member in a drive device having a moving member that moves in a first direction relative to a base, and the load sensor includes a driven member that is connected to the moving member and can move along the first direction as the moving member moves in the first direction, a first sensor element that moves together with the driven member, an attachment member for attaching the first sensor element to the driven member, a second sensor element that is fixedly attached to the base of the drive device and interacts with the first sensor element, and a guide section that guides the first sensor element along a predetermined path so that the first sensor element moves in a predetermined positional relationship relative to the second sensor element, and the attachment member has a displacement section that can be displaced in a direction perpendicular to the first direction.

The load sensor of the present invention can suppress the deterioration of detection accuracy.

1 is a schematic diagram showing the inside of a drive device including a load sensor according to an embodiment of the present invention; 2 is a cross-sectional view of the drive device taken along line II-II in FIG. 1. 3 is a cross-sectional view of the drive device showing a state in which the movable member has moved from the state shown in FIG. 2 so that the overall length of the movable member is shortened. FIG. 4 is a cross-sectional view of the drive device showing a state in which the movable member has moved further from the state shown in FIG. 3 and the driven member of the load sensor has moved. FIG. 13 is a schematic diagram showing a modified example of a drive device including a load sensor. FIG. 13 is a schematic diagram showing another modified example of a drive device including a load sensor. FIG. 2 is a side view showing the load sensor of the embodiment to which a connecting member is connected. FIG. 8 is a perspective view of the load sensor shown in FIG. 7 . IX-IX line cross-sectional view in FIG. FIG. 2 is a perspective view of a load sensor housed in a base. 4 is a schematic view of a guide portion in which a first sensor element is guided, viewed in a first direction; FIG. 13 is a reference diagram showing a positional deviation of a first sensor element in a second direction when a guide portion is not provided. FIG. 13 is a reference diagram showing a positional deviation of a first sensor element in a third direction when a guide portion is not provided. FIG. 13 is a diagram showing a state in which the position of the first sensor element is corrected by a guide portion. FIG. FIG. 11 is a schematic side view of a load sensor according to a second embodiment. FIG. 11 is a schematic top view of a load sensor according to a second embodiment.

The load sensor of one embodiment of the present invention will be described below with reference to the drawings. Note that the embodiment shown below is merely an example, and the load sensor of the present invention is not limited to the following embodiment.

In this specification, "perpendicular to A" and similar expressions do not only refer to a direction that is completely perpendicular to A, but also refer to a direction that is approximately perpendicular to A. In this specification, "parallel to B" and similar expressions do not only refer to a direction that is completely parallel to B, but also refer to a direction that is approximately parallel to B. In this specification, "C-shape" and similar expressions do not only refer to a perfect C-shape, but also refer to a shape that is visually reminiscent of a C-shape (approximately a C-shape).

As shown in Figures 1 and 2, the load sensor 1 of this embodiment detects that a load equal to or greater than a predetermined value is applied to a moving member 2 in a drive device DR that has a moving member 2 that moves in a first direction D1 relative to a base 3.

The drive device DR, in which the load sensor 1 is provided, moves the moving member 2 in the first direction D1. In this embodiment, the moving member 2 moves in the first direction D1 to drive a predetermined drive target O (see FIG. 1). The configuration of the drive device DR is not particularly limited as long as the moving member 2 moves in the first direction D1 to drive the predetermined drive target O. In this embodiment, as shown in FIG. 1, the drive device DR includes a base 3 that supports the moving member 2 movably in the first direction D1, the moving member 2, the load sensor 1, a drive unit 4 that generates a drive force to move the moving member 2, and a transmission unit 5 that transmits the drive force of the drive unit 4 to the moving member 2. In this embodiment, in the drive device DR, the drive unit 4 operates to transmit the drive force of the drive unit 4 to the moving member 2 via the transmission unit 5. As a result, the moving member 2 moves in the first direction D1, and the predetermined drive target O is driven (via the elongated member 7 described later).

The use of the drive device DR is not particularly limited as long as it can drive a predetermined drive target O by moving the moving member 2 in the first direction D1. In this embodiment, the drive device DR is an electric parking brake device that drives a brake mechanism (drive target O) such as a brake shoe. In this embodiment, the drive target O is a brake mechanism, but is not particularly limited as long as it is an object that is directly or indirectly driven by the drive device DR. The structure of the drive device DR is not particularly limited as long as it can drive a predetermined drive target O by moving the moving member 2 in the first direction D1. In this embodiment, the drive device DR further includes a long member 7 connected to the moving member 2 via a connection member 6, as shown in FIG. 1. As shown in FIGS. 1 and 2, one end of the long member 7 is connected to the connection member 6, and the other end of the long member 7 is connected to the drive target O. The drive target O is operated by the long member 7 operated by the moving member 2. In this embodiment, the long member 7 is a flexible cable (the inner cable of the control cable), but the long member may be a long member other than a cable, such as a rod. The drive device DR may have a structure in which the moving member 2 and the driven object O are directly connected without having the long member 7 connected to the moving member 2.

In this specification, the first direction D1 is the moving direction of the moving member 2 relative to the base 3. In this embodiment, the first direction D1 is the same direction (parallel direction) as the axis X (see Figures 1 and 2) direction of the moving member 2 extending in an axial manner. In this specification, one of the directions in which the moving member 2 moves is called one of the first directions D1, and the opposite direction is called the other of the first directions D1. In this embodiment, one of the first directions D1 is the direction in which the moving member 2 moves when the driving object O is driven (in this embodiment, the right side in Figures 1 and 2), and the other of the first direction D1 is the direction opposite to the direction in which the moving member 2 moves when the driving object O is driven (in this embodiment, the left side in Figures 1 and 2). In addition, the direction in which the first sensor element 12 and the second sensor element 14 described later face each other is called the second direction D2. In this embodiment, the second direction D2 is one of the directions (radial direction of the moving member 2) perpendicular to the first direction D1 (including directions toward and away from the moving member 2). More specifically, the second direction D2 is the direction (vertical direction in FIG. 2) in which the axis X of the moving member 2 and the first sensor element 12 described later are spaced apart from each other, among the directions (radial direction of the moving member 2) perpendicular to the first direction D1. The direction perpendicular to both the first direction D1 and the second direction D2 is called the third direction D3 (vertical direction in FIG. 1).

As shown in FIG. 1, the base 3 supports some or all of the components of the drive device DR, such as the load sensor 1, the moving member 2, the drive unit 4, the transmission unit 5, and the connection member 6. The shape and structure of the base 3 are not particularly limited as long as they can support the components of the drive device DR. In this embodiment, the base 3 is a casing that houses the components of the drive device DR. More specifically, the base 3 is a casing that houses the load sensor 1, the moving member 2, the drive unit 4, the transmission unit 5, and the connection member 6 inside. The structure of the base 3 is not particularly limited, but in this embodiment, the base 3 includes a first casing (the lower casing in FIG. 2) that is one half in the second direction D2, and a second casing (the upper casing in FIG. 2) that is the other half in the second direction D2.

1, the base 3 includes a sensor housing 31 in which the load sensor 1 is housed, a drive housing 32 in which the drive 4 is housed, a movement path 33 along which the connecting member 6 is guided and the moving member 2 moves, and an outlet 34 through which the elongated member 7 is led out of the base 3. In this embodiment, the moving member 2 and the connecting member 6 are housed in the movement path 33 so as to be movable in a first direction D1 relative to the base 3. In addition, in the sensor housing 31, a driven member 11 of the load sensor 1, which will be described later, is housed so as to be movable in the first direction D1 relative to the base 3.

The drive unit 4 generates a driving force that moves the moving member 2. More specifically, the drive unit 4 generates a driving force that moves the moving member 2 in order to drive the drive target O. In this embodiment, the drive force of the drive unit 4 rotates the second moving member 22 as described below, and as shown in Figures 2 to 4, the first moving member 21 moves relative to the second moving member 22 (and the base 3) in one direction in the first direction D1. The movement of the first moving member 21 relative to the second moving member 22 in the first direction D1 causes the connection member 6 to move in one direction in the first direction D1. This movement of the connection member 6 in one direction in the first direction D1 causes the elongated member 7 to be operated in one direction in the first direction D1, and the drive target O is driven.

In this embodiment, the drive unit 4 includes a motor 41. The motor 41 is configured to be rotatable in both forward and reverse directions, and can rotate the second moving member 22 in one rotation direction and the other rotation direction around the axis X. The motor 41 is connected to the transmission unit 5 via a reduction mechanism.

The transmission unit 5 transmits the driving force of the drive unit 4 to the moving member 2, which moves the moving member 2 in the first direction D1. The structure of the transmission unit 5 is not particularly limited as long as it can transmit the driving force of the drive unit 4 to the moving member 2. The transmission unit 5 includes, for example, one or more driving force transmission members such as gears. In this embodiment, the driving force transmission member of the transmission unit 5 includes a fitting member 51 that fits into the second moving member 22, as shown in FIG. 2. In this embodiment, the fitting member 51 fits into the second moving member 22 so as to rotate the second moving member 22 around the axis X and to allow the second moving member 22 to move in the first direction D1 relative to the fitting member 51. Specifically, as shown in FIGS. 2 to 4, the fitting member 51 is arranged coaxially with the second moving member 22 and engages with the outer periphery of the second moving member 22 around the axis X. As a result, when the engaging member 51 rotates around the axis X, the second moving member 22 also rotates, and the second moving member 22 can move relative to the engaging member 51 in the first direction D1 (see FIGS. 3 and 4). The structure of the engaging member 51 is not particularly limited. In this embodiment, the engaging member 51 is a gear rotatably supported on the base 3 via a bearing B. In this embodiment, when the driving force of the driving unit 4 is transmitted to the engaging member 51 via a driving force transmission member such as a plurality of gears, the engaging member 51 rotates around the axis X of the second moving member 22, causing the second moving member 22 to rotate around the axis X. As a result, the first moving member 21, whose rotation around the axis X is restricted, moves relative to the second moving member 22 in one direction in the first direction D1, as from the state shown in FIG. 2 to the state shown in FIG. 3, as will be described in detail later.

The connection member 6 connects the moving member 2 and the elongated member 7. In this embodiment, the connection member 6 is connected to the other end of the first moving member 21 in the first direction D1 as shown in FIG. 1 and FIG. 2. Also, the connection member 6 is connected to one end of the elongated member 7 in the first direction D1. In this embodiment, the connection member 6 is configured to restrict the rotation of the first moving member 21 around the axis X. Specifically, the connection member 6 is configured to engage with the base 3 in the movement path 33 of the base 3 in the direction around the axis X, and the first moving member 21 is connected to engage with the connection member 6 in the direction around the axis X. As a result, as described later, when the second moving member 22 rotates around the axis X, the first moving member 21 screwed to the second moving member 22 is suppressed from rotating around the axis X, and moves in one direction in the first direction D1 relative to the second moving member 22 without rotating around the axis X. In addition, the connecting member 6 may be integrally provided at the other end of the first moving member 21 in the first direction D1.

The moving member 2 moves in the first direction D1 relative to the base 3. In this embodiment, as shown in FIG. 2, one side of the moving member 2 in the first direction D1 is connected to the load sensor 1 (follower member 11) (via a connecting member 8 described later), and the other side of the moving member 2 in the first direction D1 is connected to the drive object O (via a long member 7). In this embodiment, the moving member 2 drives the drive object O by moving in one direction in the first direction D1 relative to the base 3 by the driving force of the drive unit 4. Note that the expression "moving in the first direction D1" includes both the movement in the first direction D1 relative to the base 3 by a part of the moving member 2 (the first moving member 21 in this embodiment) moving relative to another part of the moving member 2 (the second moving member 22 in this embodiment), and the movement of the entire moving member 2 in the first direction D1 relative to the base 3.

The configuration of the moving member 2 described in this specification is merely an example, and the shape and structure of the moving member 2 are not particularly limited as long as it is configured to move in the first direction D1 relative to the base 3 and the detection principle of the load sensor 1 described later can be applied. The moving member 2 may be composed of one member or multiple members. In this embodiment, the moving member 2 has a first moving member 21 and a second moving member 22 that can move relative to each other in the first direction D1. Details will be described later, but in this embodiment, as shown in Figures 2 and 3, after the first moving member 21 moves a predetermined amount (after the first moving member 21 moves to its movement limit (see Figure 3)), when a load of a predetermined amount or more is applied to the moving member 2, the second moving member 22 moves together with the driven member 11 to the other side in the first direction D1 against the biasing force of the biasing member 16 of the load sensor 1 (see Figure 4).

The first moving member 21 is connected to the second moving member 22 so as to move relative to the second moving member 22 in the first direction D1. In this embodiment, one side of the first moving member 21 in the first direction D1 is connected to the second moving member 22, and the other side of the first moving member 21 in the first direction D1 is connected to the connection member 6.

In this embodiment, as shown in FIG. 2, the first moving member 21 has a screw portion 211, which is screwed into the first screw portion 221 of the second moving member 22. The second moving member 22 is driven to rotate about the axis X by the driving force of the driving unit 4, so that the first moving member 21 moves relative to the second moving member 22 in the first direction D1. In this embodiment, the rotation of the first moving member 21 around the axis X is restricted, and the first moving member 21 moves in the first direction D1 relative to the second moving member 22 as the second moving member 22 rotates.

The shape and structure of the first moving member 21 are not particularly limited as long as the first moving member 21 can move relative to the second moving member 22 in the first direction D1 by driving the second moving member 22 to rotate around the axis X. In this embodiment, the first moving member 21 is configured by a shaft member extending in the first direction D1. In this embodiment, the screw portion 211 of the first moving member 21 is configured by a male screw provided on the outer periphery of the first moving member 21. However, for example, when the first screw portion of the second moving member 22 is configured by a male screw provided on the outer periphery of the second moving member 22, the first moving member may be formed in a cylindrical shape, and the screw portion of the first moving member may be configured by a female screw provided on the inner surface of the cylindrical first moving member.

The second moving member 22 rotates around the axis X to move the first moving member 21 relative to the second moving member 22 in the first direction D1. In this embodiment, the second moving member 22 is connected to the driving unit 4 (through the transmission unit 5) and rotates around the axis X by the driving force of the driving unit 4. In this embodiment, the second moving member 22 is connected to the transmission unit 5 so that the second moving member 22 rotates around the axis X by the driving force of the driving unit 4 transmitted by the transmission unit 5. Specifically, the second moving member 22 has an engaged portion 223 (see FIG. 1) that engages with the transmission unit 5 (fitting member 51) around the axis X. In this embodiment, the engaged portion 223 of the second moving member 22 is provided on the outer surface of the second moving member 22 and engages with an engaging portion (not shown) provided on the inner circumference of the fitting member 51, so that the second moving member 22 rotates around the axis X by the rotation of the fitting member 51.

In this embodiment, one side of the second moving member 22 in the first direction D1 is connected to the load sensor 1, and the other side of the second moving member 22 in the first direction D1 is connected to the first moving member 21. As shown in FIG. 2, the second moving member 22 has a first screw portion 221 that screws into the screw portion 211 of the first moving member 21. As described above, the second moving member 22 rotates around the axis X, causing the first moving member 21 to move relative to the second moving member 22 in the first direction D1.

The shape and structure of the second moving member 22 are not particularly limited as long as the second moving member 22 can rotate around the axis X to move the first moving member 21 relative to the second moving member 22 in the first direction D1. In this embodiment, the second moving member 22 is configured as a cylindrical member extending in the first direction D1. In this embodiment, the first screw portion 221 of the second moving member 22 is configured as a female screw provided on the inner surface of the cylindrical second moving member 22. However, for example, when the screw portion of the first moving member is configured as a female screw provided on the inner surface of the cylindrical first moving member, the second moving member may be configured as a shaft member, and the first screw portion of the second moving member, which is the shaft member, may be configured as a male screw provided on the outer surface of the second moving member.

2, the second moving member 22 has a second screw portion 222 that screws into the screw portion 81 of the connecting member 8. The second screw portion 222 is threaded in the opposite direction to the first screw portion 221. The screw portion 211 of the first moving member 21 and the screw portion 81 of the connecting member 8 are threaded in the opposite direction. As a result, as shown in FIGS. 2 and 3, when the second moving member 22 rotates around the axis X, the first moving member 21 moves relative to the second moving member 22 in one direction in the first direction D1, and the connecting member 8 moves relative to the second moving member 22 in the other direction in the first direction D1 (in this embodiment, until a load of a predetermined value or more is applied to the moving member 2, the connecting member 8 is suppressed from moving relative to the base 3 by the biasing member 16 provided on the load sensor 1, so that the second moving member 22 moves in one direction in the first direction D1 relative to the connecting member 8). In this embodiment, the second screw portion 222 of the second moving member 22 is configured by a female screw provided on the inner surface of the cylindrical second moving member 22. However, for example, when the connecting member is formed in a cylindrical shape and the screw portion of the connecting member 8 is configured by a female screw provided on the inner surface of the cylindrical connecting member, the second moving member may be configured by a shaft member, and the second screw portion of the second moving member, which is the shaft member, may be configured by a male screw provided on the outer surface of the second moving member.

The configuration of the moving member 2 is not limited to those shown in Figs. 1 to 4. For example, as in the modified example shown in Figs. 5 and 6, the second moving member 22 and the connecting member 8 may be connected so that the second moving member 22 and the connecting member 8 are not screwed together and no relative movement in the first direction D1 occurs between the second moving member 22 and the connecting member 8 (and the driven member 11). In the modified example shown in Figs. 5 and 6, when the second moving member 22 rotates around the axis X by the driving force of the driving unit 4, the first moving member 21 moves in one direction in the first direction D1 relative to the second moving member 22. After the first moving member 21 moves a predetermined amount (after the first moving member 21 moves to its movement limit), when a load equal to or greater than a predetermined value is applied to the moving member 2, the second moving member 22 moves in the other direction in the first direction D1 together with the driven member 11 against the biasing force of the biasing member 16 of the load sensor 1. As described below, the modified example shown in FIG. 5 has the same basic operating principle as the embodiment shown in FIG. 1 to FIG. 4, except that the configuration of the load sensor 1 differs from that of the embodiment shown in FIG. 1 to FIG. 4. The modified example shown in FIG. 6 has the same basic operating principle as the embodiment shown in FIG. 1 to FIG. 4, except that the configuration and position of the load sensor 1 differ from that of the embodiment shown in FIG. 1 to FIG. 4.

The connecting member 8 connects the moving member 2 and the load sensor 1. Specifically, the connecting member 8 connects the moving member 2 and the load sensor 1 so that the load applied to the moving member 2 in the first direction D1 can be transmitted to the load sensor 1 (follower member 11). The shape and structure of the connecting member 8 are not particularly limited as long as it can connect the moving member 2 and the load sensor 1 so that the load applied to the moving member 2 in the first direction D1 can be transmitted to the load sensor 1 (follower member 11). As shown in Figures 2 to 4, the connecting member 8 has a connecting portion 82 that is connected to the follower member 11 so that the load in the first direction D1 applied to the moving member 2 (second moving member 22) is transmitted to the follower member 11. In this embodiment, the connecting portion 82 is configured to engage with the follower member 11 in the first direction D1.

In this embodiment, the connecting member 8 is configured as an axial member extending in the first direction D1 that screws into the second moving member 22, as shown in Figures 2 to 4, 7, and 8. In this embodiment, the connecting member 8 has a threaded portion 81 that screws into the second threaded portion 222 of the second moving member 22. Note that, as in the modified example shown in Figures 5 and 6, the connecting member 8 does not have to have a threaded portion. Also, in this embodiment, the connecting member 8 is provided separately from the second moving member 22 and the driven member 11, but it may be provided integrally with the second moving member 22 or the driven member 11.

Next, the load sensor 1 will be described. As shown in Figs. 2 to 4, the load sensor 1 includes a driven member 11 connected to the moving member 2 and movable along the first direction D1 as the moving member 2 moves in the first direction D1, a first sensor element 12 that moves together with the driven member 11, a mounting member 13 for mounting the first sensor element 12 to the driven member 11, a second sensor element 14 that is fixedly mounted to the base 3 of the drive device DR and interacts with the first sensor element 12, and a guide section 15 that guides the first sensor element 12 along a predetermined path so that the first sensor element 12 moves in a predetermined positional relationship with the second sensor element 14. In this embodiment, the load sensor 1 further includes a biasing member 16 that biases the driven member 11 in the first direction D1.

<Load sensor operating principle>
Although the details of the load sensor 1 will be described later, when a load equal to or greater than a predetermined value is applied to the moving member 2, the driven member 11 moves together with the moving member 2 in the first direction D1 by a predetermined amount or more, and the positional relationship between the first sensor element 12 and the second sensor element 14 changes. This detects that a load equal to or greater than a predetermined value is applied to the moving member 2. Therefore, it is detected that a load equal to or greater than a predetermined value is applied to the drive target O. More specifically, when a load equal to or greater than a predetermined value is applied to the moving member 2, the driven member 11 moves by a predetermined amount in the first direction D1 against the biasing force of the biasing member 16, and this changes the positional relationship between the first sensor element 12, which moves together with the driven member 11 in the first direction D1, and the second sensor element 14, which is stationary relative to the base 3. The change in the sensor output at this time detects that a load equal to or greater than a predetermined value is applied to the moving member 2. Each component of the drive device DR is designed so that the biasing member 16 or the like prevents the driven member 11 from moving or keeps the amount of movement within a predetermined range until a predetermined load is applied to the moving member 2. Therefore, when the sensor output from the first sensor element 12 and the second sensor element 14 detects that the driven member 11 has moved a predetermined amount or more, it is detected that a load of a predetermined amount or more has been applied to the moving member 2 and the driven object O. Note that the "load of a predetermined amount or more" applied to the moving member 2 and the "predetermined amount" which is the amount of movement of the driven member 11 are not particularly limited, as they are appropriately changed depending on the drive device DR and the driven object O to which the load sensor 1 is applied.

The driven member 11 is directly or indirectly connected to the moving member 2, and moves along the first direction D1 as the moving member 2 moves in the first direction D1. As described above, the first sensor element 12 is connected to the driven member 11 via the mounting member 13. Therefore, as the driven member 11 moves in the first direction D1, the first sensor element 12 also moves in the first direction D1, and the positional relationship between the first sensor element 12 and the second sensor element 14 changes.

In this embodiment, the driven member 11 is biased by the biasing member 16 so that the driven member 11 is prevented from moving in the first direction D1 until a load equal to or greater than a predetermined load is applied to the moving member 2 to which the driven member 11 is connected. More specifically, when the driven object O is operated by the moving member 2, the driven member 11 receives a force from the second moving member 22 (through the connecting member 8) in one direction of the first direction D1 (in this embodiment, the other direction of the first direction D1 (the left direction in FIG. 2)). On the other hand, the driven member 11 is biased by the biasing member 16 in the opposite direction (the right direction in FIG. 2) to the force applied from the second moving member 22 to the driven member 11. Therefore, the relative movement of the driven member 11 with respect to the base 3 is suppressed and the driven member 11 is held in a predetermined position shown in FIG. 2 until a load equal to or greater than a predetermined load is applied to the second moving member 22 (until the load applied to the second moving member 22 exceeds the biasing force of the biasing member 16). When a load equal to or greater than a predetermined value that exceeds the biasing force of the biasing member 16 is applied to the second moving member 22 in the direction opposite to the biasing direction of the biasing member 16 (leftward in FIG. 2), the driven member 11 moves together with the second moving member 22 in the first direction D1 in the direction opposite to the biasing direction of the biasing member 16 (leftward in FIG. 2).

The position where the driven member 11 is provided is not particularly limited as long as the driven member 11 can move in the first direction D1 together with the moving member 2 and the first sensor element 12. In this embodiment, the driven member 11 is provided on one side of the moving member 2 (second moving member 22) in the first direction D1, but as shown in the modified example of FIG. 6, the driven member 11 may be provided on the other side of the moving member 2 (second moving member 22) in the first direction D1.

In this embodiment, the driven member 11 is provided in the sensor accommodating section 31 of the base 3 so as to be movable in the first direction D1, as shown in FIG. 1 and FIG. 2. In this embodiment, the driven member 11 is provided so as to move in the first direction D1 between an abutment wall W1 and a stop wall W2 provided in the base 3. The abutment wall W1 abuts against the driven member 11 biased in the first direction D1 by the biasing member 16 to hold the driven member 11 in a predetermined position. In this embodiment, the abutment wall W1 is formed by the inner surface of one end wall of the base 3 in the first direction D1, as shown in FIG. 2. However, the position at which the abutment wall is provided is not particularly limited as long as it is provided so as to hold the driven member 11 biased by the biasing member 16 in a predetermined position in the first direction D1. When a load equal to or greater than a predetermined value is applied to the moving member 2 and the driven member 11 moves in the first direction D1, the stopping wall W2 comes into contact with the driven member 11 to stop it, thereby limiting the amount of movement of the driven member 11 to a predetermined range. This prevents the biasing member 16 from being significantly deformed, and prevents damage to the biasing member 16 and the components of the drive device DR. The shape and structure of the stopping wall W2 are not particularly limited as long as it can limit the amount of movement of the driven member 11 to a predetermined range by coming into contact with and stopping the driven member 11. In this embodiment, the stopping wall W2 is provided at one end of a columnar support portion 35 (see FIGS. 9 and 10) that extends substantially perpendicularly from the bottom surface 3a (see FIG. 2) of the base 3 and extends in the first direction D1 and the third direction D3.

The shape and structure of the driven member 11 are not particularly limited as long as the driven member 11 can move in the first direction D1 together with the moving member 2 and the first sensor element 12. In this embodiment, the driven member 11 is a cylindrical body extending coaxially with the moving member 2, as shown in Figs. 7, 8 and 10. Specifically, the driven member 11 is configured as a bottomed cylindrical body having a bottom wall 111 extending perpendicular to the first direction D1 and a side wall 112 extending perpendicular to the bottom wall 111 (first direction D1), as shown in Figs. 2, 7 and 8. The connecting member 8 is connected to the bottom wall 111. Specifically, as shown in Figs. 2, 7 and 8, one end of the connecting member 8 penetrates the bottom wall 111 in the first direction D1, and the connecting portion 82 provided on the head portion with an expanded diameter at the end of the connecting member 8 engages with the outer surface of the bottom wall 111 in the first direction D1. In this embodiment, as shown in FIG. 8, the connecting member 8 is attached to the driven member 11 so that the relative rotation about the axis X with respect to the driven member 11 is restricted so that the rotation of the connecting member 8 about the axis X is restricted. The driven member 11 is also provided on the base 3 so that the relative rotation about the axis X with respect to the base 3 is restricted. Therefore, when the second moving member 22 rotates about the axis X, the connecting member 8 is restricted from rotating together about the axis X.

2, the biasing member 16 is accommodated in the internal space of the driven member 11 defined by the inner surfaces of the bottom wall 111 and the side wall 112. The inner surface of the bottom wall 111 functions as a spring seat against which one end of the biasing member 16, which is a coil spring, abuts in the first direction D1. The other end of the biasing member 16 in the first direction D1 abuts against a spring seat provided on the base 3. In this embodiment, the spring seat of the base 3 is provided on the stop wall W2. On one side of the outer surface of the side wall 112 in the second direction D2 (the upper side in FIG. 2), a mounting portion 112a to which the mounting member 13 is attached is provided. The shape and structure of the mounting portion 112a are not particularly limited as long as the mounting member 13 can be attached.

The biasing member 16 biases the driven member 11 in the first direction D1. Specifically, the biasing member 16 biases the driven member 11 in the first direction D1 so that the driven member 11 does not move or the amount of movement is within a predetermined range until a predetermined load is applied to the moving member 2. The shape and structure of the biasing member 16 are not particularly limited as long as it can bias the driven member 11 in the first direction D1. In this embodiment, the biasing member 16 is a coil spring extending in the first direction D1, but the biasing member 16 may be another biasing member such as an air spring or rubber. In this embodiment, the biasing member 16 is provided so that the driven member 11 presses the abutment wall W1 in the first direction D1 when the moving member 2 is in an unloaded state, such as when the drive device DR is not driven. Specifically, the biasing member 16, which is a coil spring, is provided in a compressed state, and the biasing force of the biasing member 16 is configured to hold the driven member 11 in a predetermined position until a load equal to or greater than a predetermined value is applied to the moving member 2.

The first sensor element 12 and the second sensor element 14 interact with each other to detect a change in the positional relationship between the first sensor element 12 and the second sensor element 14 and detect that a load of a predetermined amount or more has been applied to the moving member 2. Specifically, when a load of a predetermined amount or more is applied to the moving member 2, the first sensor element 12 moves in the first direction D1 together with the driven member 11 (see FIG. 4). As a result, the positional relationship between the first sensor element 12 and the second sensor element 14 when a load of a predetermined amount or more is applied to the moving member 2 as shown in FIG. 4 changes from the positional relationship between the first sensor element 12 and the second sensor element 14 before a load of a predetermined amount or more is applied to the moving member 2 as shown in FIG. 2 and FIG. 3. The load sensor 1 detects that a load of a predetermined amount or more has been applied to the moving member 2 by the sensor output corresponding to the change in the positional relationship between the first sensor element 12 and the second sensor element 14.

The configuration of the first sensor element 12 and the second sensor element 14 is not particularly limited as long as they can detect a change in the positional relationship between the first sensor element 12 and the second sensor element 14 by interacting with each other, and detect that a load of a predetermined amount or more has been applied to the moving member 2. In this embodiment, the first sensor element 12 and the second sensor element 14 constitute a magnetic field sensor that detects a change in the magnetic field due to a change in the positional relationship between the magnet and the Hall IC. The first sensor element and the second sensor element may be other sensors such as an optical sensor composed of a light emitting unit and a light receiving unit, rather than a magnetic field sensor. In this embodiment, the first sensor element 12 is a magnet, and the second sensor element 14 is a Hall IC. When the first sensor element 12 that moves in the first direction D1 together with the driven member 11 is a magnet and the second sensor element 14 is a Hall IC, wiring is provided on the side of the second sensor element 14 that is fixedly attached to the base 3, and wiring is not required for the moving first sensor element 12. Therefore, there is no need to consider wiring when arranging the first sensor element 12, and the design freedom of the load sensor 1 can be increased.

In this embodiment, the first sensor element 12 is connected to the driven member 11 via the mounting member 13 as shown in FIG. 2, FIG. 7, and FIG. 8. As a result, the first sensor element 12 moves together with the driven member 11 while maintaining a predetermined positional relationship with the driven member 11. As shown in FIG. 7 and FIG. 8, the first sensor element 12 includes a magnet 121 and a magnet housing 122. The magnet housing 122 is a container configured to allow the magnet 121 to be attached. The magnet housing 122 has a magnet accommodating portion 122a and a connecting portion 122b to which one end of the mounting member 13 is connected. As described later, the magnet housing 122 is guided through the guide portion 15 and has a shape corresponding to the internal cavity of the guide portion 15. The shape of the magnet housing 122 is not particularly limited as long as it is a shape that fits into the internal cavity of the guide portion 15, but in this embodiment, it is formed in an approximately rectangular parallelepiped shape. In this embodiment, as shown in FIG. 8 and FIG. 11, the magnet housing 122 has a protrusion P that protrudes in the second direction D2 from the surfaces provided at both ends of the magnet housing 122 in the second direction D2. The protrusion P reduces the contact area with the guide portion 15, thereby reducing the sliding resistance between the guide portion 15. In this embodiment, the protrusion P is formed in the shape of a rail extending in the first direction D1.

The second sensor element 14 is fixedly attached to the base 3. In this embodiment, the second sensor element 14 is supported by a substrate S and attached to the base 3 via the substrate S, as shown in Figures 2, 9, and 10. More specifically, the substrate S on which the second sensor element 14 is attached is fixed to a guide member G having a guide portion 15, and the guide member G is fixed to the base 3 (support portion 35), thereby fixing the second sensor element 14 to the base 3. By fixing (fixing) the second sensor element 14 to the base 3, the second sensor element 14 does not move relative to the base 3 in the first direction D1, the second direction D2, and the third direction D3.

The mounting member 13 mounts the first sensor element 12 to the driven member 11. The mounting member 13 mounts the first sensor element 12 to the driven member 11, so that when the driven member 11 moves in the first direction D1, the first sensor element 12 moves together with the driven member 11 in the first direction D1, as shown in Figs. 3 and 4. In this embodiment, the mounting member 13 has a displacement portion 131 that can be displaced in a direction perpendicular to the first direction D1, as shown in Figs. 7, 8, and 10. The displacement portion 131 displaces in response to a change in the positional relationship between the driven member 11 and the first sensor element 12 when the position of the first sensor element 12 is corrected so that it moves along a predetermined path of the guide portion 15, as described below (see Fig. 14).

The shape and structure of the mounting member 13 are not particularly limited as long as it can mount the first sensor element 12 to the driven member 11 and has a displacement portion 131. In this embodiment, the mounting member 13 is configured as an elongated plate-like member extending in the first direction D1 and supported by the driven member 11 in a cantilever manner, as shown in Figures 7, 8, and 10. The mounting member 13 configured as a plate-like member has a predetermined rigidity and a predetermined flexibility. The mounting member 13 may be a linear member such as a wire or rod having a predetermined rigidity and a predetermined flexibility. The mounting member 13 includes a mounting portion 132 provided on one end side of the mounting member 13 and attached to the outer periphery of the driven member 11, and a first sensor support portion 133 (see Figure 2) provided on the other end side of the mounting member 13 and supporting the first sensor element. A displacement portion 131 is provided between the mounting portion 132 and the first sensor support portion 133 in the first direction D1. Details of the displacement portion 131 will be described later.

As shown in Figs. 7 and 8, the mounting portion 132 is fixed to the outer periphery of the driven member 11 by a predetermined fixing means. In this embodiment, the mounting portion 132 is formed in a plate shape extending in the first direction D1 and is fixed to the outer periphery of the driven member 11 by screws. The first sensor support portion 133 is provided at the end of the mounting member 13 opposite the end where the mounting portion 132 is provided, and supports the first sensor element 12 in a cantilever manner. There is no particular limitation on the method of fixing the first sensor support portion 133 and the first sensor element 12, but in this embodiment, the first sensor support portion 133 is fixed in a state where it is inserted into the magnet housing 122 of the first sensor element 12.

The guide unit 15 guides the first sensor element 12 along a predetermined path so that the first sensor element 12 moves in a predetermined positional relationship with respect to the second sensor element 14. Here, the "predetermined path" refers to a movement path of the first sensor element 12 that enables the first sensor element 12 and the second sensor element 14 to accurately detect that a load equal to or greater than a predetermined value is applied to the moving member 2. Specifically, the predetermined path of the guide unit 15 is a path that extends substantially linearly along the first direction D1, and is configured to guide the first sensor element 12 so that at least the distance between the first sensor element 12 and the second sensor element 14 in the second direction D2 is substantially equal to a predetermined value (e.g., a design distance). In this embodiment, the predetermined path of the guide unit 15 is configured to guide the first sensor element 12 so that the distance between the first sensor element 12 and the second sensor element 14 in the second direction D2 is substantially equal to a predetermined value, and the center of the first sensor element 12 in the third direction D3 and the center of the second sensor element 14 in the third direction D3 substantially coincide (for example, the deviation between the center of the first sensor element 12 and the center of the second sensor element 14 in the third direction D3 is 5% or less of the length of the first sensor element 12 in the third direction D3).

9 and 11, the guide portion 15 has a first guide surface 151 facing the first surface 12a of the first sensor element 12 that is closer to the axis X of the moving member 2 (see FIG. 9) in the second direction D2, and a second guide surface 152 facing the second surface 12b of the first sensor element 12 that is farther from the axis X of the moving member 2 in the second direction D2. In this embodiment, the guide portion 15 has a third guide surface 153 and a fourth guide surface 154 that extend to connect the first guide surface 151 and the second guide surface 152. The third guide surface 153 and the fourth guide surface 154 face the third surface 12c and the fourth surface 12d that are perpendicular to the first surface 12a and the second surface 12b of the first sensor element 12, respectively. In this embodiment, the predetermined path of the guide portion 15 is defined by a first guide surface 151, a second guide surface 152, a third guide surface 153, and a fourth guide surface 154.

In this embodiment, the guide portion 15 is provided on a guide member G that is attached to the base 3, as shown in Figures 9 to 11. The guide member G has a fixing portion G1 that is fixed to a pair of support portions 35 that are spaced apart from each other in the third direction D3 so as to sandwich the connecting member 8 therebetween in the third direction D3, and a board connection portion G2 to which the board S is fixed. In this embodiment, the guide portion 15 is attached to the base 3 via a guide member G that is separate from the base 3, but the guide portion may be provided integrally with the base 3.

As described above, the second sensor element 14 is fixedly attached to the base 3, and the first sensor element 12 is guided along a predetermined path by the guide portion 15. Therefore, even if there is a backlash between the components constituting the drive device DR or a misalignment in the mounting position of the components, the first sensor element 12 is guided by the guide portion G, and the first sensor element 12 is corrected to an appropriate position (distance) relative to the second sensor element 14. Therefore, the deterioration of the detection accuracy of the load sensor 1 is suppressed, and erroneous detection by the load sensor 1 is suppressed. More specifically, if there is a backlash between the components constituting the drive device DR or a misalignment in the mounting position of the components, as shown in FIG. 12, a positional misalignment in the second direction D2 between the first sensor element 12 and the second sensor element 14 may occur, or as shown in FIG. 13, a positional misalignment in the third direction D3 between the first sensor element 12 and the second sensor element 14 may occur. In this case, the sensor output may change due to a change in the distance between the first sensor element 12 and the second sensor element 14 or a positional shift. Therefore, the detection accuracy of the load sensor 1 may decrease, or the load sensor 1 may determine that a load of a certain amount or more is not being applied even when a load of a certain amount or more is being applied, or may erroneously determine that a load of a certain amount or more is being applied even when a load of a certain amount or more is not being applied. In this embodiment, the guide portion 15 is configured to suppress positional shifts of the first sensor element 12 in the second direction D2 and the third direction D3 relative to the second sensor element 14. Therefore, even if positional shifts such as those shown in Figures 12 and 13 may occur due to play between the components constituting the drive device DR or shifts in the mounting positions of the components, the position of the first sensor element 12 is corrected by the guide portion 15 from the state shown by the two-dot chain line in Figure 14 to the state shown by the solid line, and it is possible to accurately detect that a load of a certain amount or more is applied to the moving member 2.

In addition, in this embodiment, the mounting member 13 has a displacement portion 131 that can be displaced in a direction perpendicular to the first direction D1, as described above. As shown in FIG. 14, the displacement portion 131 allows a change in the positional relationship between the first sensor element 12 and the driven member 11 when the position of the first sensor element 12 is corrected by the above-mentioned guide portion 15. Specifically, as shown in FIG. 14, if the guide portion 15 is not provided, and there is a backlash between the components of the drive device DR or a misalignment in the mounting position of the components occurs, the first sensor element 12 will be positioned displaced from the ideal position suitable for accurate detection (see the two-dot chain line in FIG. 12 to FIG. 14). In this embodiment, as described above, the position of the first sensor element 12 is corrected by the guide portion 15 from the position shown by the two-dot chain line in FIG. 14 to the position shown by the solid line. At this time, the positional relationship between the first sensor element 12 and the driven member 11 changes before and after being guided by the guide portion 15 (see FIG. 14). In this embodiment, the mounting member 13 is provided with a displacement portion 131, so that even if the positional relationship between the first sensor element 12 and the driven member 11 changes in a direction perpendicular to the first direction D1, the displacement portion 131 displaces in that direction to allow the change in the positional relationship between the first sensor element 12 and the driven member 11. Therefore, even if the positional relationship between the first sensor element 12 and the driven member 11 changes as the first sensor element 12 is guided by the guide portion 15, the application of excessive force to the components of the load sensor 1, such as the first sensor element 12, the mounting member 13, and the driven member 11, is suppressed. Therefore, damage to the components of the load sensor 1 is suppressed.

The "direction perpendicular to the first direction D1" in which the displacement portion 131 is displaced is preferably the second direction D2, but may be the third direction D3, or a direction between the second direction D2 and the third direction D3. The displacement portion 131 may be displaceable in the third direction D3 or other directions while being mainly displaced in the second direction D2. In this embodiment, the displacement portion 131 is configured to be able to displace the first sensor element 12 in the second direction D2. Since a positional deviation between the first sensor element 12 and the second sensor element 14 in the second direction is likely to affect the sensor performance, the displacement portion 131 is able to displace the first sensor element 12 in the second direction D2, thereby effectively suppressing a decrease in the sensor performance. In this embodiment, the displacement portion 131 is configured to be able to be slightly displaced in the third direction D3 as well.

The length L1 (see FIG. 7) of the displacement portion 131 in the first direction D1 is not particularly limited as long as it is possible to allow for changes in the positional relationship between the first sensor element 12 and the driven member 11. For example, the length L1 of the displacement portion 131 in the first direction D1 can be 0.5 to 2 times, preferably 0.8 to 1.5 times, the length L2 of the first sensor element 12 in the first direction D1.

In this embodiment, the displacement portion 131 is a leaf spring that can swing the first sensor element 12 in the second direction D2, as shown in Figures 7 and 8. As a result, when the position of the first sensor element 12 in the second direction D2 is corrected, the displacement portion 131 elastically deforms and swings in the second direction D2. By elastically deforming the displacement portion 131 provided as a leaf spring, when the positional relationship between the first sensor element 12 and the driven member 11 changes, excessive force between the components of the load sensor 1 is more likely to be reduced, and damage to the components of the load sensor 1 can be more effectively suppressed. Note that the displacement portion 131 may be composed of a wire or rod that functions like a spring, as long as it is configured to be elastically deformable.

In this embodiment, the displacement portion 131 has a narrow portion 131a in which the width of a part of the displacement portion 131 is narrower than that of the other part, as shown in FIG. 8. In this case, the displacement portion 131 is more likely to be elastically deformed in the narrow portion 131a. Therefore, it is possible to easily follow the change in the positional relationship between the first sensor element 12 and the driven member 11. In this embodiment, the displacement portion 131 has a narrow portion 131a and a wide portion 131b that is wider than the narrow portion 131a. In this case, the rigidity of the displacement portion 131 is high in the wide portion 131b, and the displacement portion 131 as a whole is prevented from bending too much. Therefore, when the first sensor element 12 and the driven member 11 move in the first direction D1 in conjunction with each other, the entire displacement portion 131 is prevented from bending too much, and the distance between the first sensor element 12 and the driven member 11 in the first direction D1 is prevented from changing. Therefore, when the displacement portion 131 has a narrow portion 131a and a wide portion 131b, it easily follows the change in the positional relationship between the first sensor element 12 and the driven member 11, while suppressing false detection due to a change in the distance between the first sensor element 12 and the driven member 11 in the first direction D1.

In addition, in this embodiment, as shown in FIG. 2, the displacement portion 131 extends at an incline so as to approach the axis X of the moving member 2 as it moves from the mounting portion 132 toward the first sensor support portion 133. In this case, compared to the case in which the displacement portion 131 extends from the mounting portion 132 parallel to the axis X of the moving member 2, the first sensor element 12 supported by the first sensor support portion 133 can be positioned closer to the axis X of the moving member 2. Therefore, the first sensor element 12 and the second sensor element 14 can be positioned closer to the moving member 2 in the second direction D2, and the base 3 can be made smaller in size in the second direction D2.

Next, the load sensor of the second embodiment will be described with reference to Figures 15 and 16. In the following description, the matters common to the first embodiment described above will be omitted, and the differences will be mainly described. All matters described in the first embodiment can be applied to the load sensor of the second embodiment as long as the object of the invention can be achieved, and the configuration of this embodiment can be used in combination with the contents described in the first embodiment. Furthermore, the effects obtained by the configuration described in the first embodiment can also be obtained in the second embodiment as long as the second embodiment has the configuration.

15 and 16, the displacement portion 131 has a first displacement portion 1311 configured to be able to displace the first sensor element 12 in the second direction D2, and a second displacement portion 1312 configured to be able to displace the first sensor element 12 in the third direction D3. The first displacement portion 1311 is a portion that mainly displaces in the second direction D2, and can be easily displaced in the direction indicated by the arrow A1 in FIG. 15. The second displacement portion 1312 is a portion that mainly displaces in the third direction D3, and can be easily displaced in the direction indicated by the arrow A2 in FIG. 16. In this embodiment, the first displacement portion 1311 is a leaf spring that can swing the first sensor element 12 in the second direction D2, and the second displacement portion 1312 is a leaf spring that can swing the first sensor element 12 in the third direction D3. In this embodiment, as described above, the displacement portion 131 has both the first displacement portion 1311, which is a portion that is primarily displaced in the second direction D2, and the second displacement portion 1312, which is a portion that is primarily displaced in the third direction D3. In this case, even if the positional relationship between the first sensor element 12 and the driven member 11 changes in both the second direction D2 and the third direction D3 due to, for example, backlash between the components that make up the drive device DR or misalignment of the mounting positions of the components, the displacement portion 131 can easily displace in the second direction D2 and the third direction D3.

Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment. Note that the above embodiment mainly describes an invention having the following configuration.

(1) A load sensor for detecting a load equal to or greater than a predetermined load being applied to a moving member in a drive device that is provided with a moving member that moves in a first direction relative to a base, the load sensor comprising:
a driven member connected to the moving member and movable along the first direction in association with movement of the moving member in the first direction;
a first sensor element moving with the driven member;
a mounting member for mounting the first sensor element to the driven member;
a second sensor element fixedly attached to the base of the actuator and interacting with the first sensor element;
a guide portion that guides the first sensor element along a predetermined path so that the first sensor element moves in a predetermined positional relationship with the second sensor element;
The mounting member has a displacement portion that is displaceable in a direction perpendicular to the first direction.

(2) The load sensor according to (1), wherein the displacement unit is configured to displace the first sensor element in a second direction in which the first sensor element and the second sensor element face each other, and/or in a third direction perpendicular to the first direction and the second direction.

(3) The load sensor according to (1) or (2), in which the displacement portion is a leaf spring that can swing the first sensor element in the second direction.

(4) A load sensor according to any one of (1) to (3), in which the displacement portion has a narrow portion in which the width of a portion of the displacement portion is narrower than that of the other portion.

(5) The displacement portion is
a first displacement unit configured to be able to displace the first sensor element in a second direction in which the first sensor element and the second sensor element face each other;
A load sensor described in any one of (1) to (4), having a second displacement portion configured to be able to displace the first sensor element in a third direction perpendicular to the first direction and the second direction.

(6) The first displacement portion is a leaf spring that can swing the first sensor element in the second direction,
The second displacement portion is a leaf spring that can swing the first sensor element in the third direction.
A load sensor according to any one of (1) to (5).

(7) The driven member is a cylindrical body extending coaxially with the moving member,
the mounting member is configured by an elongated plate-like member that is cantilevered on the driven member and extends in the first direction,
The mounting member is
a mounting portion provided on one end side of the mounting member and attached to an outer periphery of the driven member;
a first sensor support portion provided on the other end side of the mounting member and supporting the first sensor element;
the displacement portion is formed by a leaf spring extending between the mounting portion and the first sensor support portion,
The load sensor according to any one of (1) to (6), wherein the displacement portion extends at an incline so as to approach the axis of the movable member as it moves from the mounting portion toward the first sensor support portion.

(8) A load sensor according to any one of (1) to (7), in which the first sensor element is a magnet.

LIST OF SYMBOLS 1 Load sensor 11 Follower member 111 Bottom wall 112 Side wall 112a Mounting portion 12 First sensor element 12a First surface 12b Second surface 12c Third surface 12d Fourth surface 121 Magnet 122 Magnet housing 122a Magnet accommodating portion 122b Connection portion 13 Mounting member 131 Displacement portion 131a Narrow width portion 131b Wide width portion 1311 First displacement portion 1312 Second displacement portion 132 Mounting portion 133 First sensor support portion 14 Second sensor element 15 Guide portion 151 First guide surface 152 Second guide surface 153 Third guide surface 154 Fourth guide surface 16 Pressing member 2 Moving member 21 First moving member 211 Thread portion 22 Second moving member 221 First screw portion 222 Second screw portion 223 Engaged portion 3 Base portion 3a Bottom surface of base portion 31 Sensor accommodating portion 32 Drive portion accommodating portion 33 Movement path 34 Lead-out portion 35 Support portion 4 Drive portion 41 Motor 5 Transmission portion 51 Fitting member 6 Connection member 7 Elongated member 8 Linking member 81 Screw portion 82 Linking portion B Bearing D1 First direction D2 Second direction D3 Third direction DR Drive device G Guide member G1 Fixed portion G2 Board connection portion L1 Length in first direction of displacement portion L2 Length in first direction of first sensor element O Driven object P Protrusion S Board W1 Contact wall W2 Stop wall X Axis of moving member

Claims (8)

A load sensor for detecting a load equal to or greater than a predetermined load being applied to a moving member in a drive device that is provided with a moving member that moves in a first direction relative to a base, the load sensor comprising:
a driven member connected to the moving member and movable along the first direction in association with movement of the moving member in the first direction;
a first sensor element moving with the driven member;
a mounting member for mounting the first sensor element to the driven member;
a second sensor element fixedly attached to the base of the actuator and interacting with the first sensor element;
a guide portion that guides the first sensor element along a predetermined path so that the first sensor element moves in a predetermined positional relationship with the second sensor element;
The mounting member has a displacement portion that is displaceable in a direction perpendicular to the first direction. The load sensor according to claim 1, wherein the displacement unit is configured to displace the first sensor element in a second direction in which the first sensor element and the second sensor element face each other, and/or in a third direction perpendicular to the first direction and the second direction. The load sensor according to claim 2, wherein the displacement portion is a leaf spring that can swing the first sensor element in the second direction. The load sensor according to claim 3, wherein the displacement portion has a narrow portion in which the width of a portion of the displacement portion is narrower than that of the other portion. The displacement portion is
a first displacement unit configured to be able to displace the first sensor element in a second direction in which the first sensor element and the second sensor element face each other;
The load sensor according to claim 1 , further comprising: a second displacement portion configured to be capable of displacing the first sensor element in a third direction perpendicular to the first direction and the second direction. the first displacement portion is a leaf spring capable of swinging the first sensor element in the second direction,
The second displacement portion is a leaf spring that can swing the first sensor element in the third direction.
The load sensor according to claim 5 . The driven member is a cylindrical body extending coaxially with the moving member,
the mounting member is configured by an elongated plate-like member that is cantilevered on the driven member and extends in the first direction,
The mounting member is
a mounting portion provided on one end side of the mounting member and attached to an outer periphery of the driven member;
a first sensor support portion provided on the other end side of the mounting member and supporting the first sensor element;
the displacement portion is formed by a leaf spring extending between the mounting portion and the first sensor support portion,
The load sensor according to claim 1 , wherein the displacement portion extends at an incline so as to approach an axis of the movable member as the displacement portion extends from the attachment portion toward the first sensor support portion. The load sensor of claim 1, wherein the first sensor element is a magnet.

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