Displacement detection device

Abstract

To provide a displacement detection device which has high reliability, and a reduced manufacturing cost.SOLUTION: Provided is a displacement detection device, comprising: a housing 4; a metal slider 20 which is annexed to a linear motion device which is provided with a drive part installed in the housing 4 and a rod 3 provided with a screw part to which a drive force is transmitted from an output gear of the drive part and reciprocating along an axis X while being blocked from rotating with respect to the housing 4, the slider being secured to the rod 3; a slide contact member 21 which is attached to the slider 20 while in slide contact with a guide part G which is formed in the housing 4; a magnet 24 attached to the rod 3 in a non-contact state with the slide contact member 21 and reciprocating together with the rod 3; and a control part for detecting the relative movement of the magnet 24 and installed in the housing 4.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a displacement detection device for a rod in a linear motion device or the like, which transmits the rotation of a drive unit to a rod and moves back and forth while its rotation is restricted by a housing. [Background technology]

[0002] Conventionally, such a displacement detection device is disclosed in, for example, Patent Document 1 (see

[0008] ,

[0012] and FIGS. 1 and 9).

[0003] This displacement detection device is installed in, for example, a linear motion mechanism. The linear motion mechanism has a rod that threads onto a rotationally driven nut member, and the rod moves back and forth linearly while being prevented from rotating. When the linear motion mechanism is driven, the axial displacement of the rod is constantly detected by the displacement detection device.

[0004] This displacement detection device includes a displacement sensor attached to a housing and a permanent magnet that moves back and forth facing the displacement sensor. The permanent magnet is insert-molded from a synthetic resin material to form a magnet block. The magnet block is placed in a long groove formed in the rod and is fixed to the rod from the back side with a bolt member through a through hole also provided in the rod. As the rod moves back and forth, the side of the magnet block abuts against the inner surface of the housing, preventing rotation of the rod.

[0005] According to this device, the magnet block has the functions of detecting rod displacement and preventing rotation, making it possible to make the displacement detection device smaller and lighter. Moreover, because the magnet block is placed and fixed in the long groove, it is securely held to the rod and can prevent the rod from rotating. In addition, only one bolt is required to fasten the magnet block to the rod, reducing the number of parts, making assembly easier and reducing costs. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-232035 Summary of the Invention [Problem to be solved by the invention]

[0007] In the conventional displacement detector described above, the magnet block, which is made by insert-molding the magnet with a resin material, receives torque from the inner surface of the housing to stop the rotation of the rod when it moves. For this reason, the strength of the magnet block may be insufficient to increase the thrust of the linear motion mechanism.

[0008] Furthermore, because the magnet block is fastened to the rod from the back side with a bolt, the structure of the resin part becomes complicated, which increases the manufacturing costs of the mold used for insert molding.

[0009] Furthermore, when attaching the magnet block to the rod, the linear motion mechanism must be inverted and the bolts fastened from the back side of the rod, which makes assembly work complicated and limits productivity improvements.

[0010] As described above, conventional displacement detection devices have various problems to be solved, and there has been a demand for a highly reliable displacement detection device that can be manufactured at low cost. [Means for solving the problem]

[0011] (Features and configuration) The characteristic configuration of the displacement detection device according to the present invention is as follows: Housing and a drive unit provided in the housing; a rod having a screw portion to which a driving force is transmitted from an output gear of the drive portion, and which reciprocates along an axis while being prevented from rotating relative to the housing; a metal slider fixed to the rod; a sliding contact member attached to the slider in a state of sliding contact with a guide portion formed on the housing; a magnet attached to the rod in a state of not contacting the sliding contact member and reciprocating together with the rod; a control unit provided in the housing and configured to detect relative movement of the magnet; Preparation, The slider has a flat receiving surface that abuts against the sliding contact member and receives a reaction force from the housing, and also has a plate-shaped protruding portion on one side of which the receiving surface is formed, and an engaging portion and an engaged portion that engage with each other to fix the sliding contact member to the protruding portion are arranged separately between the sliding contact member and the protruding portion. It is characterized by the following points.

[0012] (effect) By making the slider out of metal as in this configuration, the slider can reliably withstand the anti-rotation torque that occurs between the slider and the guide portion when the rod moves back and forth.

[0013] Furthermore, since the magnet is not in contact with the sliding contact member and does not bear the rotation prevention torque, the risk of the magnet being damaged is eliminated, and a displacement detector with improved durability can be obtained.

[0014]

[0015] (effect) As in this configuration, by providing a flat receiving surface on the metal slider and configuring it to receive the force from the sliding contact member, the rotation restriction function of the rod can be reliably exerted. Furthermore, it is possible to increase the torque of the linear motion mechanism, making it possible to apply it to a higher thrust force.

[0016]

[0017] (effect) By providing such an engaging portion and an engaged portion, the work of attaching the sliding contact member to the slider is simplified, and therefore a displacement detection device can be obtained with reduced work costs.

[0018] (Features and configuration) In the displacement detection device of the present invention, the slider can be configured to have a bottom portion that is continuous with the protrusion portion in a bent state, and to fix the slider to the rod by inserting a fastening member into an attachment hole provided in the bottom portion.

[0019] (effect) With this configuration, the work of attaching the sliding contact member to the slider and the work of attaching the slider to the rod can be separated. If the work is done before the sliding contact member is attached, it is easy to fasten the fastening member from the protruding portion side. Therefore, there is no need to change the position of the rod during assembly, and assembly work can be performed efficiently.

[0020] (Features and configuration) In the displacement detection device of the present invention, the magnet is held by a magnet block, and the magnet block has a protruding portion that protrudes parallel to the surface of the magnet and in a direction intersecting the axis, and the position of the magnet along the axis is maintained by the protruding portion abutting against the slider, and in the direction intersecting the axis, the magnet block and the slider do not come into contact, and the magnet is maintained in position by the abutment between the magnet block and the housing.

[0021] (effect) With this configuration, the reaction force acting on the slider from the housing to prevent rotation of the rod is not transmitted to the magnet, thereby improving the durability of the magnet even though it is relatively fragile.

[0022] Furthermore, since the magnet block and slider are not in contact in the direction intersecting the axis, even if the slider rotates slightly due to a reaction force from the housing, the magnet does not displace in the direction intersecting the axis, significantly improving the accuracy of magnet position detection. [Brief explanation of the drawings]

[0023] [Figure 1] FIG. 1 is an explanatory diagram showing an example of use of a displacement detection device according to an embodiment of the present invention; [Figure 2] An explanatory diagram showing the configuration of the drive unit [Figure 3] An exploded perspective view showing the configuration of the drive unit [Figure 4] 1 is a cross-sectional side view showing the configuration of a displacement detection device; [Figure 5] FIG. 1 is a perspective view showing the configuration of a main part of a displacement detection device; [Figure 6] A longitudinal cross-sectional view showing the configuration of the main part of the displacement detection device. [Figure 7] FIG. 1 is a perspective view showing the configuration of a control unit. [Figure 8] FIG. 1 is a perspective view showing the configuration of a spacer substrate; [Figure 9] FIG. 1 is a perspective view showing a fitting structure of a first substrate and a second substrate; [Figure 10] An explanatory diagram showing the grounding structure of the control unit [Figure 11] An explanatory diagram showing the heat dissipation structure of the control unit [Figure 12] An explanatory diagram showing the sealing structure of the control unit DETAILED DESCRIPTION OF THE INVENTION

[0024] (overview) The displacement detection device S according to the present invention can be used, for example, in a linear motion mechanism provided in a rear wheel steering device of a vehicle. In the linear motion mechanism, for example, a cylindrical nut 2 is rotated by an electric motor 1, which is a drive unit M, and a rod 3 threadedly inserted into the nut 2 is moved back and forth. A sliding surface that abuts against the inner surface of a housing 4 of the linear motion mechanism is formed on a part of the rod 3, and the rod 3 is configured to move back and forth without rotating.

[0025] 1 and 2 show the configuration of the linear motion mechanism according to this embodiment. The linear motion mechanism includes a control unit C provided on the left side of FIG. 1 and a drive unit M provided on the right side. The control unit C has a linear motion sensor 25 that measures the displacement state of the rod 3, and calculates the position of the rod 3 based on a signal from this linear motion sensor 25. Based on the calculation result, the control unit C supplies a drive signal to the drive unit M to move the rod 3 to a desired position.

[0026] (Drive unit) 2 and 3, the drive unit M of this embodiment includes a stator 5 having an axis X along the movement direction of the linear motion mechanism, and a cylindrical rotor 6 that rotates inside the stator 5. A rod 3 is inserted inside the cylindrical rotor 6. The rotor 6 is supported on both sides of the housing 4 by rotor bearings 7 on both outer sides along the axis X, sandwiching the opposing position of the stator 5.

[0027] (planetary gear mechanism) A planetary gear mechanism P is connected to one end of the rotor 6. Specifically, a sun gear P1 is formed on the outer surface of the end of the rotor 6. Three planetary gears P2 mesh with the sun gear P1, and a ring gear P3 fixed to the housing 4 meshes with the outer surface of the planetary gear P2.

[0028] The carrier K of the planetary gear P2 is screwed and fixed to the outer periphery of the nut 2 which is screwed onto the rod 3. The carrier K has a first carrier K1 which is fixed to the outer surface of the nut 2, and a second carrier K2 which is fitted and fixed to the outside of the first carrier K1. Three shaft members 8 which respectively support the three planetary gears P2 are fixed to the second carrier K2.

[0029] The nut 2 is cylindrical, and has a female trapezoidal thread 9a formed on its inner surface as an output gear 9 for the drive unit M. On the other hand, the rod 3 has a male trapezoidal thread 10a formed on its outer surface as a threaded portion 10. The nut 2 is made of brass to provide wear resistance. The rod 3 moves back and forth without rotating relative to the housing 4 by abutting a sliding contact member 21 (described below) against the inner surface of the housing 4. A bearing portion 11 using a thrust bearing is fitted onto the outer surface of the nut 2, and this bearing portion 11 is fitted inside the inner surface of the housing 4.

[0030] The first carrier K1 is fitted onto one end of the nut 2 and screwed and fixed via a fixing screw portion 12. A radially protruding bulge 2a is formed on the other end of the nut 2, and the inner member 11a of the bearing portion 11 is sandwiched between the bulge 2a and the end face of the first carrier K1 along the axis X. This configuration simplifies the fixing of the bearing portion 11 and the first carrier K1 to the nut 2, thereby improving the efficiency of the assembly work.

[0031] The second carrier K2, which holds the planetary gear P2, is fitted and fixed to the outside of the first carrier K1. This fitting and fixing is performed using two types of fitting portions. One is a cylindrical first fitting portion Ka formed on the far side in the fitting direction along the axis X when viewed from the second carrier K2 side. This is formed by a cylindrical fitting outer surface formed on the outer surface of the first carrier K1 and a cylindrical fitting inner surface formed on the inner surface of the second carrier K2. The other is a spline-shaped second fitting portion Kb adjacent to the first fitting portion Ka and positioned on the near side in the fitting direction when viewed from the second carrier K2 side.

[0032] The second fitting portion Kb is configured, for example, in a star-shaped cross section perpendicular to the axis X. This prevents the first carrier K1 and the second carrier K2 from rotating relative to each other, making it possible to configure a durable carrier K. Furthermore, when threading the first carrier K1 into the nut 2, the second fitting portion Kb can be used as an engagement portion for a fastening tool. The first carrier K1 and the second carrier K2 are formed of steel instead of the conventional brass, thereby achieving weight reduction and cost reduction.

[0033] In this embodiment, the housing 4 has a particularly narrow shape, and the bearing portion 11 needs to be located deep inside the carrier K. Therefore, the installation procedure is as follows: the bearing portion 11 is attached to the nut 2, the bearing portion 11 is clamped by the first carrier K1, and then these are fixed to the housing 4. The second carrier K2 is then attached to the first carrier K1.

[0034] The bearing 11 is fixed using an annular spacer 13 that abuts against the outer member 11b of the bearing 11, and a retaining ring 14 that abuts against the spacer 13 to hold the bearing 11 and spacer 13 in place. The retaining ring 14 is, for example, a C-shaped snap ring that fits into a groove 15 formed on the inner surface of the housing 4.

[0035] With this configuration, the spacer 13 can be attached before the second carrier K2 is attached, and the dimensions of the spacer 13 can be set regardless of the dimensions of the second carrier K2, which tends to have a relatively large diameter. This increases the degree of freedom in designing the attachment location of the bearing 11 and improves the efficiency of the attachment work of the bearing 11. Furthermore, since the size of the bearing 11 and the size of the second carrier K2 can be set separately, the degree of freedom in designing the components of the planetary gear mechanism P is increased.

[0036] Furthermore, by using the spacer 13, even if there is an error in the formation position of the groove portion 15, by using a spacer 13 of an appropriate thickness, the outer member 11b can be fixed to the housing 4 without any rattle. Furthermore, by making the spacer 13 a completely annular member, the spacer 13 abuts against the entire circumference of the outer member 11b, improving the effect of preventing the outer member 11b from coming off.

[0037] After the bearing portion 11 has been fixed, the second carrier K2 is fitted and fixed to the first carrier K1. The planetary gear P2 may be attached to the second carrier K2 either before or after the second carrier K2 is attached to the first carrier K1. The ring gear P3 is fitted to the inner surface of the housing 4 as shown in FIG. 2.

[0038] (Guide part) When the rod 3 is reciprocated by the driving unit M, the rotation of the rod 3 is prevented by the housing 4. For this reason, as shown in Figures 4 to 6, a guide unit G is formed on the rod 3 opposite the threaded unit 10, spanning the rod 3 and the housing 4.

[0039] The guide portion G is composed of a slider 20 provided on the rod 3, a sliding member 21 attached to the slider 20, and a guide surface 22 provided on the housing 4 so that the sliding member 21 slides over a predetermined distance.

[0040] The slider 20 is a member having a U-shaped cross section perpendicular to the axis X, as shown in Figures 5(a) and (b). The slider 20 is fixed to the rod 3 by a mounting bolt, which is a fastening member 23, through a mounting hole 20b provided in a bottom 20a forming the U-shape. The mounting procedure involves inserting the rod 3 into the housing 4, and aligning the slider mounting position on the rod 3 with the positions of the opposing guide surfaces 22 formed in the opening of the housing 4. In this state, the slider 20, to which the sliding contact member 21 has been attached in advance, is positioned and fastened by the fastening member 23.

[0041] The sliding contact member 21 is attached to the slider 20 by inserting a groove-shaped insertion portion 21a formed in the sliding contact member 21 into a pair of U-shaped protrusions 20c of the slider 20. Claw portions are formed as engaging portions 21c on the inner wall 21b that forms the insertion portion 21a of the sliding contact member 21, and the claw portions are engaged with holes that are provided as engaged portions 20d in the pair of protrusions 20c. By engaging in this way using a so-called snap fit, the attachment work of the sliding contact member 21 to the slider 20 is simplified and the work costs can be reduced.

[0042] Furthermore, the tip edge of each protruding portion 20c is formed with a step portion 20e by cutting both ends along the direction of the axis X. As a result, when the insertion portion 21a of the sliding contact member 21 is inserted into the protruding portion 20c, the part of the tip edge excluding the step portion 20e is exposed on the upper surface of the sliding contact member 21, as shown in Fig. 5(a), and the sliding contact member 21 is prevented from rattling along the direction of the axis X relative to the protruding portion 20c.

[0043] Furthermore, the outward facing surface of each of the pair of sliding contact members 21 serves as sliding contact surface 21d, which comes into sliding contact with guide surface 22 provided on housing 4 to prevent rotation of rod 3. To ensure this prevention of rotation, the outward facing surfaces of the pair of protruding portions 20c of slider 20 are formed as flat receiving surfaces 20f, which come into face-to-face contact with flat surface 21e formed on the inside of insertion portion 21a of sliding contact member 21. By providing such receiving surfaces 20f and flat surface 21e, the rotation restriction function of rod 3 is reliably exerted, enabling the linear motion mechanism to have a high torque.

[0044] The slider 20 is made of a metal material such as steel or stainless steel, and can reliably withstand the anti-rotation torque of the rod 3 that is received as a reaction force from the guide surface 22 when the rod 3 moves back and forth. On the other hand, the sliding contact member 21 is made of a material with a low coefficient of friction, such as fluororesin.

[0045] Furthermore, by separating the slider 20 and the sliding contact member 21, the sliding contact member 21 can be attached to the slider 20 after the slider 20 is attached to the rod 3. If the sliding contact member 21 is attached before the slider 20 is attached, it becomes easy to fix the fastening member 23 between the pair of protruding portions 20c. With this configuration, when assembling the slider 20, there is no need to change the position of the rod 3, such as by inverting it, and an efficient assembly operation is possible.

[0046] (Control unit) The position of the rod 3 is detected by the control unit C. This detection is performed by a magnet 24 provided between the pair of sliding contact members 21 and a linear motion sensor 25 provided on a control board 26 in a state where it faces the magnet 24 closely.

[0047] 5, the magnet 24 is formed as a magnet block 24a by inserting a long piece of resin material. This magnet block 24a is fixed to the rod 3, but is attached so that an external force that would prevent the rod 3 from rotating is not input from the sliding contact member 21 to the magnet 24.

[0048] 5(b), the magnet block 24a is inserted between a pair of sliding contact members 21, and is arranged so that the back surface of the magnet block 24a abuts against the first seats 20g at two locations formed on the bottom 20a of the slider 20. As a result, the detection surface of the magnet 24 is set at a predetermined height relative to the surface of the rod 3.

[0049] Moreover, protruding portions 24b are provided near both ends of the magnet block 24a, and second seats 24c formed on these protruding portions 24b sandwich each of the two sliding contact members 21 in the direction along the axis X. At this time, if the second seats 24c are made to lightly abut against the sliding contact members 21, the magnet block 24a will not rattle when the rod 3 moves back and forth, and the accuracy of measuring the position of the rod 3 will be further improved.

[0050] Furthermore, the positioning of magnet 24 in the width direction, i.e., the direction intersecting axis X when viewed in a direction perpendicular to the surface of magnet 24, is performed by housing 4. That is, second guide surface 27, which is provided in the housing 4 near guide surface 22 and parallel to said guide surface 22, comes into sliding contact with protruding portion 24b, thereby positioning magnet 24 and guiding its movement.

[0051] In this way, after fixing the slider 20 and the sliding member 21 to the rod 3 inserted into the housing 4, the magnet block 24a is positioned relative to the sliding member 21 and the housing 4, whereby the magnet 24 can be easily installed relative to the rod 3.

[0052] With this configuration, when the rod 3 moves back and forth, no force that would prevent the rotation of the rod 3 acts on the magnet 24 from the sliding contact member 21. This eliminates the risk of damaging the magnet 24, and makes it possible to obtain a displacement detection device S with a rational structure and increased durability.

[0053] 4 and 7 show the configuration of the control unit C. The magnet 24 constituting the control unit C is fixed to the side of the rod 3 and is disposed with its detection surface facing upward. A linear motion sensor 25 is disposed facing and close to this magnet. The linear motion sensor 25 is mounted on a first substrate 26a (described later) and detects the position information of the rod 3. Based on the signal obtained by the linear motion sensor 25, the control unit C calculates the position of the rod 3 and transmits a drive signal to the drive unit M to move the rod 3 to the desired position.

[0054] 7(a) and 7(b), the control unit C includes, for example, a first board 26a and a second board 26b as the control board 26. The first board 26a is the board facing the magnet 24 and is a so-called control system board provided with the linear motion sensor 25 and the like. The second board 26b is a so-called power system board provided with a power supply circuit and the like.

[0055] In this embodiment, a spacer substrate 26c having, for example, an annular rectangular overall shape is provided between the first substrate 26a and the second substrate 26b, electrically connecting the first substrate 26a and the second substrate 26b. The first substrate 26a, the second substrate 26b, and the spacer substrate 26c are attached to a frame member 38 before being fixed to the housing 4. The frame member 38 also includes a connector 38a that connects the first substrate 26a and the like to the vehicle's ECU. By stacking multiple substrates in this manner, the overall planar area of ​​the control unit C can be reduced, improving the mountability of the control unit C to a target device such as a linear motion mechanism.

[0056] 8, the spacer substrate 26c is provided with a plurality of relay terminals 30 that connect the soldered portions of the first substrate 26a and the soldered portions of the second substrate 26b. Here, the relay terminals 30 are configured in the shape of straight rods. The relay terminals 30 are made of a material that has excellent mechanical strength, electrical conductivity, thermal conductivity, and corrosion resistance, such as a Cu alloy-based material or an Fe alloy-based material.

[0057] Each relay terminal 30 is disposed to penetrate the spacer substrate 26c. For example, a plurality of holes are formed in the spacer substrate 26c in advance, and the relay terminals 30 are inserted into the holes. Alternatively, the spacer substrate 26c can be insert-molded with the relay terminals 30 embedded in predetermined positions.

[0058] To connect the first board 26a and the second board 26b to each of the relay terminals 30, it is necessary to accurately position the first board 26a and the second board 26b with respect to all of the relay terminals 30. For this reason, as shown in Fig. 9, a first positioning portion 31 is provided between the spacer board 26c and the first board 26a to position them relative to each other.

[0059] For example, the spacer substrate 26c may be provided with a first convex member 31a that protrudes toward the first substrate 26a and is fitted into a first fitting hole 31b provided in the first substrate 26a. On the other hand, the spacer substrate 26c and the second substrate 26b may also be provided with a second convex member 32a provided on the spacer substrate 26c and a second fitting hole 32b provided in the second substrate 26b as second positioning portions 32.

[0060] The provision of such first positioning portion 31 and second positioning portion 32 facilitates the connection of spacer substrate 26c to first substrate 26a and second substrate 26b, improving the efficiency of assembling multiple layers of substrates, thereby achieving a low-cost substrate mounting structure.

[0061] (Heat-resistant structure) Numerous electronic components are mounted on the first and second substrates 26a and 26b, which generate a certain amount of heat during normal use. This heat can cause changes in the dimensions of each substrate, which can change the mechanical properties of the heated soldered joints. As a result, the relative positions of the soldered joints on the first and second substrates 26a and 26b can shift along the planar direction of the substrates, causing problems such as cracking of the soldered joints.

[0062] Therefore, the spacer substrate 26c of this embodiment is provided with slits 33a as partitions 33 that separate the regions A in which a predetermined number of relay terminals 30 are arranged. Specifically, as shown in Fig. 8, a plurality of slits 33a extending perpendicularly to the periphery of the spacer substrate 26c are formed for each region A of a predetermined area. To achieve this, only the portions of the slits 33a are protruded toward the center of the spacer substrate 26c, and the slits 33a are formed inside these protruding portions 34. This ensures connection rigidity between the regions A on both sides of the slits 33a.

[0063] This configuration allows relative displacement between predetermined regions A of spacer substrate 26c, absorbing changes in the posture of relay terminal 30 that occur as the temperature of first substrate 26a and second substrate 26b rises. Therefore, excessive bending force is not applied to the soldered portions of first substrate 26a and second substrate 26b, and the soldered portions can be effectively protected.

[0064] (Grounding structure) In the substrate mounting structure of this embodiment, the first substrate 26a and the second substrate 26b are provided with the following grounding structure to suppress noise generation: A ground terminal 36 is provided for at least one of the first fixing portion 35a used to fix the first substrate 26a to the housing 4 and the second fixing portion 35b used to fix the second substrate 26b to the housing 4.

[0065] This ground terminal 36 grounds the second substrate 26b etc. to the frame member 38 by attaching the second substrate 26b etc. to the frame member 38. Furthermore, the frame member 38 is fixed to the housing 4 using screw members 39 etc., so that the second substrate 26b etc. are grounded to the housing 4.

[0066] 10(a) and 10(b), a ground terminal 36 formed by bending a metal plate is attached to a fixing screw 37 that fixes the second substrate 26b to a frame member 38, for example. The ground terminal 36 is in contact with the ground circuit of the second substrate 26b. One side of the ground terminal 36 is provided with an elastic portion 36a that protrudes away from the fixing screw 37. The elastic portion 36a protrudes outward from the second substrate 26b, and is configured so that the second substrate 26b and the housing 4 are electrically connected simply by attaching the frame member 38 having the second substrate 26b to the housing 4.

[0067] This configuration can reduce the effects of noise on first substrate 26a and second substrate 26b from surrounding devices. Furthermore, when first substrate 26a and second substrate 26b are attached to various devices, grounding work can be performed at the same time, resulting in a highly reliable substrate mounting structure with excellent attachment workability.

[0068] (heat dissipation structure) The first board 26a and second board 26b of this configuration generate heat during use. In particular, the amount of heat generated by the second board 26b, which is a power supply board, is greater than that of the first board 26a. If the amount of heat generated becomes excessive, there is a possibility that the mounted components and soldered portions of the second board 26b may be damaged. Therefore, the board mounting structure of this configuration is provided with the following heat dissipation structure.

[0069] 11, a pressing portion 40 that presses, for example, a portion of second substrate 26b toward housing 4 is formed on a portion of frame member 38. A heat dissipation portion 41 is formed on the back surface of the portion of second substrate 26b that faces pressing portion 40, and when second substrate 26b etc. are attached to housing 4, this heat dissipation portion 41 abuts against a heat dissipation sheet 42 provided on housing 4. In other words, the pressing portion 40 is configured to press the back surface of second substrate 26b so that heat dissipation portion 41 abuts against heat dissipation sheet 42 reliably.

[0070] With this configuration, simply by attaching the frame member 38, which already holds the second substrate 26b, etc., to the housing 4, the heat dissipation section 41 provided on the second substrate 26b is reliably pressed against the heat dissipation sheet 42 of the housing 4, thereby achieving a good heat dissipation effect.

[0071] As in this configuration, the necessary control boards 26 are divided into the first control board 26a and the second power board 26b, and the heat dissipation section 41 is provided on the second board 26b, thereby enhancing the heat removal effect. Furthermore, because the control boards 26 are divided according to the level of heat generation, damage to soldered portions caused by heat, particularly on the second power board 26b, can be more effectively prevented.

[0072] Furthermore, the pressing portion 40 of this configuration simply presses the heat dissipation portion 41 against the heat dissipation sheet 42, and does not restrict the thermal expansion of the second substrate 26b etc. along its planar direction. Therefore, no unexpected stress is generated in the second substrate 26b, and damage to the soldered portions can be effectively prevented.

[0073] (Seal structure) The first substrate 26a, the second substrate 26b, and the spacer substrate 26c are fixed to the housing 4 while being attached to one side of a frame member 38, and the opposite side of the frame member 38 is covered with a cover member 43. When the frame member 38 and the cover member 43 are attached to the housing 4, annular seal members 44 are disposed between the peripheral edge of one side of the frame member 38 and the housing 4, and between the peripheral edge of the other side of the frame member 38 and the peripheral edge of the cover member 43.

[0074] This seal member 44 is made of, for example, any of various rubber materials having a circular cross section, and has a planar shape that corresponds to the peripheral shape of the frame member 38. At least one of the frame member 38, cover member 43, and housing 4, which are arranged opposite each other, has a fixing groove 45 formed therein, into which the seal member 44 fits.

[0075] This makes it easier to install the seal member 44 by making it less likely to shift position when installing the frame member 38 and the cover member 43. Also, since the seal member 44 is prevented from shifting position after installation, it is possible to obtain a substrate mounting structure that has excellent dustproof and waterproof properties over the long term. [Industrial Applicability]

[0076] The displacement detection device of the present invention can be widely used for detecting the displacement of a rod in a linear motion device or the like, which transmits the rotation of a drive unit to a rod and moves back and forth while its rotation is restricted by a housing. [Explanation of symbols]

[0077] 3 rods 4. Housing 9 Output Gear 10 Threaded part 20 Slider 20a bottom 20b Mounting hole 20c Projection part 20d Engaged part 20f receiving surface 21 sliding contact member 21c Engagement part 23 Fastening members 24 Magnet 24a Magnetic Block 24b Overhang C control section G guide part M Drive Unit S Displacement detection device X-axis center

Claims

1. Housing and a drive unit provided in the housing; a rod having a screw portion to which a driving force is transmitted from an output gear of the drive portion, and which reciprocates along an axis while being prevented from rotating relative to the housing; a metal slider fixed to the rod; a sliding contact member attached to the slider in a state of sliding contact with a guide portion formed on the housing; a magnet attached to the rod in a state of not contacting the sliding contact member and reciprocating together with the rod; a control unit provided in the housing and configured to detect relative movement of the magnet; The slider has a planar receiving surface that abuts against the sliding member and receives the reaction force from the housing, and also has a plate-shaped protruding portion on one side of which the receiving surface is formed, and an engaging portion and an engaged portion that engage with each other to fix the sliding member to the protruding portion are arranged separately between the sliding member and the protruding portion.

2. 2. The displacement detection device according to claim 1, wherein the slider has a bottom portion that is continuous with the protrusion portion in a bent state, and the slider is configured to be fixed to the rod by inserting a fastening member into an attachment hole provided in the bottom portion.

3. 3. The displacement detection device of claim 1, wherein the magnet is held by a magnet block, and the magnet block has a protruding portion that protrudes parallel to the surface of the magnet and in a direction intersecting the axis, and the position of the magnet along the axis is maintained by the protruding portion abutting against the slider, and in the direction intersecting the axis, the magnet block and the slider do not come into contact, and the magnet is maintained in position by the magnet block abutting against the housing.

4. A housing, a drive unit provided in the housing; a rod having a screw portion to which a driving force is transmitted from an output gear of the drive portion, and which reciprocates along an axis while being prevented from rotating relative to the housing; a metal slider fixed to the rod; a sliding contact member attached to the slider in a state of sliding contact with a guide surface of a guide portion formed on the housing; a magnet attached to the rod and reciprocating with the rod; a control unit provided in the housing and configured to detect relative movement of the magnet; A displacement detection device in which the magnet is not in contact with the sliding contact member via a gap along the direction in which the rod rotates, and is guided in movement by a second guide surface provided in the housing parallel to the guide surface.

Images