Position detection sensor

Abstract

Position detection sensor, which is mounted in a sensor mounting groove (42) which opens on a side surface of an actuator (40) and extends in an axial direction of the actuator (40), comprising: a housing (14) that accommodates a sensor base body, and a guide element (16) which is inserted into the sensor mounting groove (42), wherein the guide element (16) has such a shape that when the guide element (16) is inserted into the sensor mounting groove (42) the guide element (16) must be inserted straight into the sensor mounting groove (42), wherein at a position where the guide element (16) comes into contact with an opening edge of the sensor mounting groove (42), the guide element (16) must first be rotated in one direction about an axis parallel to an axis of the actuator (40) and then in one direction opposite to this one direction, and wherein after the guide element (16) is inserted into the sensor mounting groove (42) its attachment to the sensor mounting groove (42) is completed by attaching a fastening element (56).

Description

Background of the invention

[0001] The present invention relates to a position detection sensor and in particular to a position detection sensor which can be attached, for example, to an actuator in order to continuously detect an operating state of the actuator.

[0002] To detect the position of a piston inside a cylinder acting as an actuator, a magnet is typically attached to the piston, and a magnetic sensor, which detects the magnet's magnetic field, is located on the outside of the actuator. As the piston moves back and forth, driven by the flow of pressurized fluid, its position can be verified by the magnet's magnetic field, which is detected by the magnetic sensor.

[0003] In this case, the position detection sensor is formed by connecting a cylindrical mounting element to a holder that accommodates the magnetic sensor. The position detection sensor is mounted in a sensor groove that has a circular cross-section and opens along the entire axial length of a side face of the cylinder (compare, for example, Japanese patent publication JP 2008-051800 A).

[0004] When installing the position detection sensor, the cylindrical mounting element is first inserted into the sensor groove from one axial end face of the cylinder. The mounting element is then moved to a predetermined position along the sensor groove. Next, the tightness of the bolt connecting the holder and the mounting element is adjusted. The mounting of the position detection sensor is completed by engaging a protruding section, formed in the opening of the sensor groove, between the holder and the mounting element.

[0005] DE 20 2008 007 384 U1 discloses a fastening structure for securing a sensor with an L-shaped leg in a T-profile groove. To insert the sensor into the groove, it must first be inserted straight into the groove in a predetermined orientation. As soon as the leg of the sensor comes into contact with the bottom of the groove, it is tilted into its final assembly position. Document DE 20 2008 007 384 U1 represents the closest prior art.

[0006] DE 20 2006 010 289 U1 discloses a fastening device for fixing a sensor to a groove. The fastening device comprises a holding device and a clamping device by which the holding device can be fixed to the groove by clamping action.

[0007] DE 201 08 649 U1 discloses a mounting structure consisting of a sensor and a profile groove. The sensor has a hollow cylindrical sensor housing with axially extending flats on two opposing surfaces. The profile groove has a receiving section with a circular cross-section and an insertion section with two parallel walls. The sensor is mounted by inserting the sensor housing into the insertion section with the flats aligned parallel to the walls of the insertion section, followed by rotation of the sensor housing within the receiving section. Summary of the invention

[0008] However, with the position detection sensor according to Japanese patent publication JP 2008-051800 A, it is difficult to increase work efficiency because attaching the position detection sensor to the cylinder is done by manually inserting the mounting element from one axial end of the cylinder to the desired position. Furthermore, a large working area near the axial end of the cylinder is required.

[0009] The present invention was developed based on the aforementioned publication, taking into account the problems mentioned above. Its objective is to propose a position detection sensor that allows for quick and easy attachment of the sensor to an actuator without requiring an unnecessarily large working space. Furthermore, it should be difficult to detach the position detection sensor from the sensor mounting groove when the sensor is only temporarily attached to the actuator.

[0010] This problem is essentially solved by the invention through the features of claim 1.

[0011] Advantageous embodiments of the invention are set out in the dependent claims.

[0012] According to the present invention, a position detection sensor is mounted in a sensor mounting groove that opens on a side face of an actuator and extends in an axial direction along the actuator. The position detection sensor comprises a housing that receives a sensor body and a guide element inserted into the sensor mounting groove. The guide element is shaped such that, when the guide element is inserted into the sensor mounting groove, it must first be rotated in a direction about an axis parallel to the axis of the actuator and then rotated in a direction opposite to this rotation. After the guide element has been inserted into the sensor mounting groove, its fastening in the sensor mounting groove is completed by using a fastening element.

[0013] With the position detection sensor described above, it is not necessary to provide a working space for mounting the position detection sensor in the axial direction of the actuator, since the position detection sensor can be mounted from a side face of the actuator. Similarly, when removing the guide element from the sensor mounting groove, the process of rotating the guide element in one direction and then rotating it in the opposite direction is required, just as when inserting the guide element into the sensor mounting groove.Even if the position detection sensor is attached to an actuator that is in a state where the sensor mounting groove opens to the side or downwards, or in a only temporarily secured state before the mounting element is attached, there is no risk of the position detection sensor unintentionally falling out of the sensor mounting groove.

[0014] In the position detection sensor described above, a mounting opening for the fastening element is preferably designed such that it passes through the guide element from a side of the housing opposite the guide element. Accordingly, the fastening process for securing the guide element can be easily carried out in a state where it is inserted into the sensor mounting groove.

[0015] Furthermore, sections can be cut out at both ends along the longitudinal direction of the housing, and the mounting opening can pass through the guide element from a bottom surface of each of these cut-out sections. Since the position detection sensor is secured at both ends in the sensor mounting groove, it can be mounted securely. Because the heads of the fasteners are accommodated within the cut-out sections, the fasteners do not protrude from the housing.

[0016] In the position detection sensor, the sensor mounting groove preferably comprises a first guide surface, which is planar and extends vertically downwards from a side face of the actuator; a second guide surface, which is a defined distance from the first guide surface and lies parallel to it; and a third guide surface, which is curved in an arc and connects the end sections of the first and second guide surfaces. This allows the guide element to be held stably in the sensor mounting groove.

[0017] Furthermore, the guide element can have a first guided surface, which is planar and extends vertically downwards from the housing; a second guided surface, which is a fixed distance from the first guided surface and parallel to the first guided surface; a third guided surface, which projects in an arc and is connected to an end section of the first guided surface; a fourth guided surface, which is connected to the second guided surface and inclined in a direction in which it approaches the first guided surface and is subsequently inclined in a direction in which it again becomes parallel to the second guided surface; and a fifth guided surface, which is connected to the fourth guided surface and is substantially parallel to the second guided surface. An end section of the third guided surface can be connected to an end section of the fifth guided surface.This feature of the invention results in the central line of the guide element in the cross-section in the width direction being drawn in the form of a slightly meandering line, so that a design is obtained in which the position detection sensor, whose guide element has been inserted into the sensor mounting groove, cannot be separated from the sensor mounting groove by simply pivoting the position detection sensor in one direction.

[0018] Furthermore, the distance between the first and second guided surfaces can be essentially equal to the maximum wall thickness between the third and fifth guided surfaces, and slightly smaller than the distance between the first and second guided surfaces. The radius of curvature of the third guided surface is essentially equal to the radius of curvature of the third guide surface. Accordingly, when the guide element is inserted into the sensor mounting groove, pivoting of the guide element can be permitted. In particular, when fasteners are used, the third guided surface of the guide element is pressed into contact with the third guide surface of the sensor mounting groove, thus easily fixing the position detection sensor to the cylinder base.

[0019] In the position detection sensor, the actuator can be a cylinder device. In this case, the cylinder device preferably comprises a piston in which a magnet is installed inside a cylinder body. Several magnetic sensors can be accommodated in the housing along an axial direction. With such a design, it is possible to detect the position of the piston very accurately within its stroke range.

[0020] Furthermore, the fastening element can be a screw with an external thread. In this embodiment, the fastening elements can be of simple design, and the holding force that keeps the position detection sensor in the sensor mounting groove can be easily adjusted.

[0021] Since the position detection sensor described above, according to the present invention, can be attached to a side surface of the actuator, it is not necessary to provide a working space for attaching the position detection sensor in the axial direction of the actuator. Furthermore, in a state where the position detection sensor is only temporarily mounted on the actuator, there is no risk of the position detection sensor accidentally falling out of the sensor mounting groove.

[0022] Further features, advantages, and possible applications of the present invention will become apparent from the following description in conjunction with the accompanying drawings. All features described and / or illustrated, individually or in any combination, constitute the subject matter of the invention, irrespective of their compilation in the claims or their cross-reference. Brief description of the drawings Fig. Figure 1 is a perspective view of the position detection sensor according to an embodiment of the present invention; Fig. Figure 2 is a front view of the position detection sensor according to Fig. 1; Fig. 3 is a section along line III-III in Fig. 2; Fig. Figure 4 is a schematic side view of the position detection sensor according to Fig. 1 and a cylindrical base body and Fig. 5A to 5D are views that illustrate the process of attaching the position detection sensor according to Fig. 1. Illustrate on the cylindrical base body. Description of preferred embodiments

[0023] A preferred embodiment of a position detection sensor according to the present invention is described below with reference to the accompanying drawings. In the Fig. Figures 4 and 5A to 5D show only a part of a cylindrical base body (actuator) 40 schematically in the vicinity of an area in which a sensor mounting groove 42 is formed in the cylindrical base body 40.

[0024] The position detection sensor 10 according to the embodiment of the present invention is attached to an outer surface of the cylinder base body, which comprises a piston (not shown) in which a magnet is attached.

[0025] As in the Fig. 1, Fig. 2 to Fig. As shown in Figure 3, the position detection sensor 10 comprises an elongated housing 14 and a guide element 16. The housing 14 accommodates a circuit board 12a, which includes a circuit for a signal processing system, and a circuit board 12b, in which a magnetic sensor (not shown) is integrated. A guide element 16 projects outwards from the housing 14 and extends over substantially the entire length of the housing 14. The housing 14 and the guide element 16 are integrally formed from a single resin or plastic material. In order for the position detection sensor 10, according to the present embodiment, to linearly detect the displacement of the piston, which moves back and forth inside the cylinder base 40 from one end to the other, the position detection sensor 10 has a length that is slightly shorter than the length of the cylinder base 40 in the axial direction.For this purpose, several magnetic sensors are provided on the circuit board 12b at equal intervals over essentially its entire length.

[0026] As in Fig. As shown in Figure 4, the housing 14 comprises a first side surface 18 and a first bottom surface 20, which are arranged substantially perpendicular to each other, and a second bottom surface 22, which intersects the first bottom surface 20 obliquely. An upper part of the first side surface 18 and an end section of the second bottom surface 22 are connected by an upper surface 21, which is substantially parallel to the first bottom surface 20, and by a second side surface 23, which is substantially parallel to the first side surface 18.

[0027] The guide element 16 comprises a first guided surface 24, which is planar and extends substantially vertically downwards from the first base surface 20 of the housing 14, and a second guided surface 26, which is spaced a defined distance from the first guided surface 24 and arranged parallel to it. An end section of the first guided surface 24 is connected to a third guided surface 28, which projects outwards and is curved in the direction of extension of the second base surface 22.On the other hand, the second guided surface 26 is connected to a fifth guided surface 32, which runs substantially parallel to the second guided surface 26, via a fourth guided surface 30, which is curved and gently inclined from the end section of the second guided surface 26 in a direction in which it approaches the first guided surface 24, and then inclined in a direction in which it again runs parallel to the second guided surface 26. An end section of the third guided surface 28 is connected to an end section of the fifth guided surface 32. This feature of the invention creates a slightly meandering line 34 in the cross-section of the guide element 16, central in the width direction.

[0028] As in Fig. As shown in Figure 1, U-shaped cutouts 36 are formed at both ends of the housing in the longitudinal direction 14 at the ends of the upper surface 21. Mounting holes 38, which pass through the fourth guided surface 30 and the fifth guided surface 32, are formed in the bottom surfaces of the cutouts 36. Internal threads are formed on the inner surfaces of the mounting holes 38. As also shown in Fig. As shown in Figure 1, fastening elements 56 with external threads (fastening screws) can be screwed into the fastening holes 38.

[0029] As in Fig. As shown in Figure 4, the sensor mounting groove 42 is formed in the cylindrical base body 40 of the actuator. This groove opens on a side surface 58 of the cylindrical base body 40 and extends along its entire length in the axial direction. The sensor mounting groove 42 is formed by a first guide surface 44, which extends vertically downwards from the side surface 58 of the cylindrical base body 40; a second guide surface 46, which extends vertically downwards and is parallel to the first guide surface 44; and a third guide surface 48, which is arc-shaped and connects the end sections of the first guide surfaces 44 and the second guide surface 46.

[0030] The distance between the first guided surface 24 and the second guided surface 26 is essentially equal to the maximum wall thickness between the third guided surface 28 and the fifth guided surface 32 and slightly smaller than the opening width of the sensor mounting groove 42, that is, the distance between the first guide surface 44 and the second guide surface 46. On the other hand, the radius of curvature of the third guided surface 28 of the guide element 16 is essentially equal to the radius of curvature of the third guide surface 48 of the sensor mounting groove 42.

[0031] In the drawings, reference numeral 50 denotes a conductor wire that supplies the necessary electrical current to the electronic components of the magnetic sensor and other components mounted on circuit boards 12a and 12b, and for reading position detection signals with respect to the piston, which are detected by the magnetic sensor. Furthermore, reference numeral 52 denotes an actuating unit for switching the position detection sensor 10 on and off, and reference numeral 54 denotes an LED that indicates an operating status of the position detection sensor 10.

[0032] The position detection sensor 10 according to the present embodiment is essentially constructed as described above. Next, with reference to the Fig. Sections 4 and 5A to 5D describe the operating modes and effects of the position detection sensor 10. It is understood that the upward and downward directions in the Fig. 5A to 5D are not limited to the vertical direction.

[0033] When the position detection sensor 10 is attached to the elongated cylindrical base body 40, the fifth guided surface 32 of the guide element 16 follows the second guide surface 46 of the sensor mounting groove 42, and the distal end of the guide element 16 is inserted straight into the sensor mounting groove 42 (compare Fig. 5A). The entire fifth guided surface 32 is inserted into the sensor mounting groove 42. At a position where the fourth guided surface 30 comes into contact with the opening edge of the second guide surface 46, the guide element 16 is pressed into the sensor mounting groove 42 (compare Fig. 5B), while the position detection sensor 10 is gradually pivoted (i.e., rotated clockwise in the drawing). Then, when the second bottom surface 22 of the housing 14 reaches a state where it is essentially parallel to the side surface 58 of the cylindrical base body 40, the position detection sensor 10 is returned to its original orientation (i.e., rotated counterclockwise in the drawing) (compare Fig. 5C).

[0034] At this time, the first guided surface 24 and the second guided surface 26 of the guide element 16 are positioned next to and parallel with the first guide surface 44 and the second guide surface 46 of the sensor mounting groove 42, respectively. Furthermore, the third guided surface 28 of the guide element 16 is inserted against the third guide surface 48 of the sensor mounting groove 42, essentially without gaps. Additionally, the first bottom surface 20 of the housing 14 is brought into contact with the side surface 58 of the cylindrical base body 40, essentially parallel to each other. In this state, the externally threaded fastening elements 56 are screwed into the mounting holes 38 of the housing 14, and the distal ends of the fastening elements 56 protrude by a defined amount from a boundary region between the fourth guided surface 30 and the fifth guided surface 32 of the guide element 16.They are brought into position against the third guide surface 48 of the sensor mounting groove 42 (compare . Fig. 5D). Once this is done, rotation of the position detection sensor 10 is prevented, and the third guided surface 28 of the guide element 16 is pressed into contact with the third guide surface 48 on the side of the first guide surface 44 of the sensor mounting groove 42, thus completing its mounting. A case was described in which distal end sections of the mounting elements 56 protrude from a boundary region between the fourth guided surface 30 and the fifth guided surface 32. However, depending on where the mounting surface 38 is located, the distal end sections can also protrude from the fourth guided surface 30 or from the fifth guided surface 32.

[0035] To remove the position detection sensor 10 from the cylinder base 40, for example for maintenance work or the like, the reverse procedure is carried out as when attaching the position detection sensor 10 to the cylinder base 40.

[0036] Specifically, the fastening elements 56 are first retracted by loosening (unscrewing) their screwed-in state, at least to a point where the distal ends of the fastening elements 56 are drawn inwards from the fourth guided surface 30 and the fifth guided surface 32 of the guide element 16. Next, the position detection sensor 10 is pivoted (rotated clockwise) so that the second bottom surface 22 of the housing 14 lies substantially parallel to the side surface 58 of the cylindrical base body 40, and so that sections of the first guided surface 24 and the second guided surface 26 of the guide element 16 slide out of the sensor mounting groove 42.When the second bottom surface 22 of the housing 14 reaches a state in which it is essentially parallel to the side surface 58 of the cylinder base 40, the position detection sensor 10 is gradually pivoted in the opposite direction (i.e., rotated counterclockwise), and the position detection sensor 10 is pulled out of the sensor mounting groove 42. In this way, the position detection sensor 10 can be removed from the cylinder base 40.

[0037] As described above, the position detection sensor 10 cannot be separated from the cylinder base 40 without first pivoting (rotating) the position detection sensor 10 in one direction and then pivoting (rotating) it in the opposite direction. Therefore, after the guide element 16 has been inserted into the sensor mounting groove 42, the position detection sensor 10 is prevented from unintentionally falling out in the state prior to the attachment of the fastening elements 56, for example, when an operation is carried out to adjust the position of the position detection sensor 10 relative to the longitudinal direction of the sensor mounting groove 42.In particular, even if the cylinder base body 40 is arranged and oriented so that its axis is horizontal, with the opening of the sensor mounting groove 42 facing sideways or downwards, there is no concern that the position detection sensor 10 will be separated (fall out) from the sensor mounting groove 42 in a provisionally mounted state by the weight of the position detection sensor 10 or by vibrations.

[0038] Since, according to the present embodiment, the position detection sensor 10 can be inserted in a direction that intersects the axial direction of the cylinder base 40, there is no need to provide a large working space in the axial direction of the cylinder base 40 to facilitate its attachment. Similarly, removing the guide element 16 from the sensor mounting groove 42 requires rotating the guide element 16 in one direction and then rotating it in the opposite direction. Therefore, even in a provisionally mounted state before attaching the fastening elements 56, there is no risk of the position detection sensor 10 unintentionally falling out of the sensor mounting groove 42.

[0039] Furthermore, cut-out sections 36 are formed at both ends of the housing 14 in a longitudinal direction, and the mounting holes 38 for the fasteners 56 extend from the bottom surfaces of the cut-out sections 36 through the guide element 16. Therefore, the position detection sensor 10 can be securely mounted. Additionally, the heads of the fasteners 56 are received in the cut-out sections 36, so that the fasteners 56 do not protrude from the housing 14.

[0040] Although in the present embodiment the guide element 16 extends substantially along its entire length in the longitudinal direction of the housing 14, alternatively guide elements can also be provided only at the locations where the mounting holes 38 for the mounting elements 56 are provided. Although the mounting holes 38 are provided at both ends in the longitudinal direction of the housing 14, a mounting hole 38 can also be provided at only one location, for example, at a central position in the longitudinal direction of the housing 14. Even if the housing 14 is formed from a single resin or plastic together with the guide element 16, it is also possible to design the housing 14 from a hollow, hard plastic in which a receiving space for the circuit boards 12a, 12b is provided, and from a soft plastic with which the receiving space is filled.

[0041] The position detection sensor according to the present invention is not limited to the embodiment described above, and it is understood that various additional or modified designs can be provided without departing from the scope of the invention as defined in the appended claims. Even though an example has been described in the present embodiment in which a fluid pressure cylinder is used as the actuator, the actuator is not limited to such a cylinder. For example, an electrical actuator can also be used. Finally, the concepts of the invention can readily be applied to linear actuators as well.

Claims

[1] Position detection sensor mounted in a sensor mounting groove (42) which opens on a side face of an actuator (40) and extends in an axial direction of the actuator (40), comprising: a housing (14) that accommodates a sensor base body, and a guide element (16) which is inserted into the sensor mounting groove (42), wherein the guide element (16) has such a shape that when the guide element (16) is inserted into the sensor mounting groove (42) the guide element (16) must be inserted straight into the sensor mounting groove (42), wherein at a position where the guide element (16) comes into contact with an opening edge of the sensor mounting groove (42), the guide element (16) must first be rotated in one direction about an axis parallel to an axis of the actuator (40) and then in one direction opposite to this one direction, and wherein after the guide element (16) is inserted into the sensor mounting groove (42) its attachment to the sensor mounting groove (42) is completed by attaching a fastening element (56). [2] Position detection sensor according to claim 1, characterized by , that a mounting hole (38) for the mounting element (5 6) passes through the guide element (16) from a side of the housing (14) opposite the guide element (16). [3] Position detection sensor according to claim 2, characterized by , that cut-out sections (36) are formed at both ends in a longitudinal direction of the housing (14), and that the fastening hole (38) passes through the guide element (16) from a bottom surface of each of the fastening sections (36). [4] Position detection sensor according to one of the preceding claims, characterized by , that the sensor mounting groove (42) a first guide surface (44) which has a planar shape and extends vertically downwards from a side surface of the actuator (40), a second guide surface (46) which has a defined distance from the first guide surface (44) and runs parallel to the first guide surface (44), and a third guide surface (48) which is curved in an arc and connects end sections of the first guide surface (44) and the second guide surface (46). [5] Position detection sensor according to claim 4, characterized by , that the guide element (16) a first guided surface (24) which is designed to be flat and extends vertically downwards from the housing (14), a second guided surface (26) which has a defined distance from the first guided surface (24) and runs parallel to the first guided surface (24), a third guided surface (28) which projects in an arc and is connected to an end section of the first guided surface (24), a fourth guided surface (30), which is connected to the second guided surface (26), is inclined in a direction in which it approaches the first guided surface (24), and is subsequently inclined in a direction in which it becomes parallel to the second guided surface (26) again, and a fifth guided surface (32) which is connected to the fourth guided surface (30) and runs essentially parallel to the second guided surface (26), wherein an end section of the third guided surface (28) is connected to an end section of the fifth guided surface (32). [6] Position detection sensor according to claim 5, characterized by, that a distance between the first guided surface (24) and the second guided surface (26) is essentially equal to a maximum wall thickness between the third guided surface (28) and the fifth guided surface (32) and slightly smaller than a distance between the first guided surface (44) and the second guided surface (46), and that a radius of curvature of the third guided surface (28) is essentially equal to a radius of curvature of the third guided surface (48). [7] Position detection sensor according to any of the preceding claims, characterized by , that the actuator (40) is a cylinder device, wherein the cylinder device has a piston inside a cylinder base body (40) in which a magnet is attached, and wherein several magnetic sensors are accommodated in the housing (14) along a longitudinal direction of the housing (14). [8] Position detection sensor according to any of the preceding claims, characterized by, that the fastening element (56) is a screw.

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