JPH04110976U - acceleration detector - Google Patents

Abstract

(57) [Summary] [Purpose] To make it easier to assemble an acceleration detector using a differential transformer, simplify manufacturing, and at the same time reduce costs and improve performance. [Structure] A primary coil 6a of a differential transformer in which a movable magnetic body 4 that moves according to acceleration is arranged concentrically around the outer periphery;
6b and the secondary coils 7a, 7b pass through the movable magnetic body 4, and both ends of the movable magnetic body 4 are supported by leaf springs 3a, 3b, respectively.
The leaf springs 3a and 3b are sandwiched and fixed between the end face of the body part 2-1 and the end face of the lid part 2-2 of the magnetic case 2, which form a magnetic path between the primary and secondary coils. Furthermore, the free end of each leaf spring is preferably fixed with a piece of magnetic material 5 which is coupled to the movable magnetic material. With this structure, the accuracy of the gap g between both ends of the movable magnetic body, which determines the performance of the detector, is
Since it is determined by the dimensional accuracy of the piece 5, it is easy to achieve high accuracy and easy to assemble. Furthermore, since the leaf spring can be fixed at the same time as the lid part 2-2 is caulked and fixed, the assembly process and manufacturing are simplified.

Description

[Detailed explanation of the idea]

0001

[Industrial application field]

This idea is related to acceleration detectors for detecting the acceleration of moving objects such as automobiles. Ru.

0002

[Conventional technology]

Some well-known acceleration detectors include a differential controller that detects the movement of a magnetic body due to acceleration. There are some things that can be detected by the

0003 An example is shown in FIG. This differential transformer type acceleration detector 41 is arranged in the direction A in the figure. When an acceleration of Each leaf spring is elastically deformed and moved in the direction B in the figure. Due to this movement, the magnetic body 44 The length of the part existing in the right secondary coil 47b is the same as that in the left secondary coil 47a. The length is longer than the existing portion, and there is a difference in the induced voltage between the secondary coils 47a and 47b. acceleration is detected based on this difference.

0004 In the figure, 46 is a primary coil, and 42 is a case. In addition, the specifics of this type of detector As a conventional example, there is the one shown in Utility Model Application Publication No. 59-95266. .

[0005]

[Problem that the idea aims to solve]

This type of detector generates a voltage difference by changing the relative position of the secondary coil and the magnetic body. Therefore, high positioning accuracy is required, and assembly efficiency decreases due to time-consuming adjustments. However, there is a problem in that assembly costs are also high.

[0006] This idea proposes a differential transformer type acceleration detector that eliminates this assembly problem. This is what we are trying to provide.

[0007]

[Means to solve the problem]

In order to solve the above problems, this idea uses a movable magnetic body as the primary core of a differential transformer. the coil, and both ends of the movable magnetic body that penetrates the secondary coil and protrudes from the coil. The two leaf springs are supported by a magnetic material covering the outer periphery of the differential transformer. The end face of the body of the case and both ends of the movable magnetic body in the direction of movement are kept in contact with each other with a predetermined gap. Secure it by sandwiching it between the end faces of the lid of the case facing the same direction.

[0008] This detector is designed by inserting the case lid into the opening in the body and caulking the edge of the opening in the body. fix the lid to the body, or attach pieces of magnetic material to both ends of the movable magnetic material in the direction of movement. Connect by press-fitting, etc., and sandwich the free end of the leaf spring between this piece and the movable magnetic body. It is more preferable in terms of accuracy and assemblability to fix the parts by using them. In addition, the movable magnetic When connecting a piece of magnetic material to both ends of a magnetic body, attach this piece to one of the movable magnetic bodies. Ensure a specified gap between this piece and the lid of the magnetic case. Ru.

[0009]

[Effect]

The magnetic flux generated by the primary coil passes through the movable magnetic body and reaches the secondary coil, A voltage is induced in the secondary coil. The magnitude of the induced voltage at this time is within the secondary coil. The amount of magnetic flux passing through the secondary coil is determined by the amount of magnetic flux passing through the secondary coil. It is determined by the magnetic resistance value of the magnetic circuit that exists between the primary coil and the secondary coil, With this idea, there is a gap between the movable magnetic body and the lid of the case on both sides. ) changes and moves to increase the change in magnetic flux with respect to the displacement of the movable magnetic body. Detection sensitivity is improved.

0010 In other words, when acceleration occurs and the movable magnetic body moves toward one end, the movable magnetic body and that end The gap between the lid of the magnetic case facing the surface decreases at one end and decreases at the other end. Expanding. Therefore, on one end side, the magnetic resistance due to the gap decreases and the magnetic resistance of the part concerned decreases. The amount of flux passing through (the amount of magnetic flux passing through the magnetic case to the secondary coil) is lower than that of the conventional structure. The magnetic resistance due to the gap increases at the other end, which is opposite to the above. The following phenomenon occurs. This effect of increasing and decreasing the amount of magnetic flux passing between one end and the other end causes the There is also a larger difference in the voltage of the secondary coil induced by overmagnetic flux than before, and therefore, By measuring this difference, it is also possible to detect minute accelerations.

[0011] As described above, the detection principle of the detector of this invention is based on the phase between the movable magnetic body and the secondary coil. Conventional detector that creates an induced voltage difference between two secondary coils due to positional changes Unlike this, a voltage difference (detector output) is generated due to the gap difference on both sides of the movable magnetic body. In order to ensure the relative position accuracy of the coil and the movable magnetic body (this is because there is no reference plane) (very difficult) is not necessary. On the other hand, the gap accuracy at both ends of the movable magnetic body is improved. However, in this design, the leaf spring is connected to the end surface of the body of the magnetic case and the lid. Since it is sandwiched and fixed between the end faces of the parts, this requirement can be easily met. In other words, the dimensions from the leaf spring clamping surface of the lid to the inner surface, and the dimension from the end surface of the movable magnetic body to the leaf spring. The gap accuracy at both ends can be sufficiently increased by simply determining the dimensions up to the screw attachment part.

0012 In addition, when securing the lid and body of the case by caulking, the connection between the two and the leaf spring must be fixed. The structure and assembly process are further simplified because the fixing of the parts is completed at the same time.

[0013] In addition, a piece of magnetic material is connected to both ends of the movable magnetic material, and this piece is used to create a plate. When fixing the free end of the spring, the accuracy of the distance between the two leaf springs and the distance from the leaf spring to The dimensional accuracy up to the end face of the gap can be easily increased, and the gap accuracy can be improved. It becomes easier to increase sensitivity. Moreover, at this time, the piece is press-fitted and fixed to the movable magnetic body. This may cause unnecessary stress (for example, stress due to welding heat, etc.) to be applied to the leaf spring. This also leads to stabilization of performance.

[0014]

【Example】

FIG. 1 shows an outline of the first embodiment. This acceleration detector 1 is a case made of magnetic material. 2. This case 2 has a cylindrical body 2-1 and openings at both ends of this body. It consists of two cup-shaped lids 2-2 that close the Both ends of the leaf springs 3a and 3b, which have a double-sided structure, are sandwiched between the baffle surfaces (Fig. point c is the clamping part). The left and right lid parts 2-2 are inserted into the opening of the body part 2-1, Bend (crimp) the thin opening edge of the body inward to attach the body and lid. are fixed to each other, and the leaf springs 3a and 3b are also fixed at the same time.

[0015] A movable magnetic body 4 is arranged between the central parts of the leaf springs 3a and 3b, and the movable magnetic body 4 The protrusions of the magnetic piece 5 are press-fitted into the holes machined on both end faces to free the leaf springs 3a and 3b. The end is fixed to the movable magnetic body 4. In this state, connect the other end of piece 5 and the lid of the case. A predetermined gap g is secured between the inner surface of the portion 2-2 and the inner surface of the portion 2-2.

[0016] The outer periphery of the movable magnetic body 4 includes primary coils 6a and 6b that generate magnetic flux, and primary coils 6a and 6b that generate magnetic flux. Secondary coils 7a and 7b for detecting changes are installed concentrically. These coils As can be seen from the figure, 6a and 7a and 6b and 7b are stacked in pairs, respectively, and the pairs are stacked. The coils are arranged separately on the left and right. In addition, a yoke 8 is installed between this pair of coils. It has been placed.

[0017] The detector of the first embodiment configured as described above has a movable magnetic body 4 when the moving body accelerates or decelerates. On the other hand, if the mass is M, a force of F=M・G is applied. This force F is the leaf spring The movable magnetic body 4 is elastically deformed to a position balanced with the elastic forces of 3a and 3b. Displace. The amount of displacement at this time is determined by the spring constants of the leaf springs 3a, 3b and the movable magnetic body 4. If the mass M is constant, it is proportional to the acceleration G, and therefore the inner surface of the lid part 2-2 and the piece The gap g with respect to the end face of 5 also changes in proportion to the acceleration G.

[0018] The change in this gap is based on the assumption that the acceleration in the direction A in the figure is now applied to the acceleration detector 1. Assuming that the movable magnetic body 4 moves in the B direction, it decreases on the right side and decreases on the left side. increases with Therefore, the magnetic flux movement between the right lid part 2-2 and the movable magnetic body 4 is The amount of magnetic flux transmitted from the primary coil 6b to the secondary coil 7b increases, and 2 Next, a larger voltage is induced in the coil than when the acceleration is zero. On the other hand, there is a gap on the left side. As the magnetic resistance increases due to the increase in the magnetic flux, the magnetic flux passing through the secondary coil 7a increases. As the output voltage decreases, the output voltage also decreases. The secondary coil output at this time is the above-mentioned Due to the action, that of 7b becomes larger than before, and that of 7a becomes smaller than before. It becomes. Therefore, the difference in output between both coils in terms of acceleration is naturally larger than before. Therefore, highly sensitive detection can be expected.

[0019] Also, if the acceleration acting in the A direction in the figure is excessive, then the movable magnetic body 4 hits the inner surface of the lid and is prevented from moving further. Therefore, due to excessive acceleration, There is no excessive deflection of the leaf springs 3a, 3b, and there is no problem of permanent deformation or damage of the leaf springs. It disappears.

[0020] Furthermore, by using the above assembly structure, the gap between both ends of the movable magnetic body can be reduced. It is possible to easily improve the accuracy of various dimensions, including the assembly process itself. is simplified.

[0021] FIG. 2 is a schematic configuration diagram of the second embodiment. This acceleration detector 11 is It has the same structure as the example and works in the same way. However, two leaf springs 13a and 13b forms a cantilever beam, and a convex portion of a small diameter is provided at both ends of the movable magnetic body 14. Each plate spring is attached to the movable magnetic body 14 by press-fitting the ring-shaped piece 15 onto the outer periphery of the plate spring. The difference from the first embodiment is that the free end of the second embodiment is fixed. In this way, the leaf spring By using the ring-shaped piece 5 to attach the free end, machining of the part becomes easier. becomes easier.

[0022]

[Effect of the idea]

As mentioned above, the acceleration detector of this invention connects the end face of the body of the magnetic case to Since the leaf spring is sandwiched and fixed between the end face of the lid, the gap between both ends of the movable magnetic body is reduced. The dimensional accuracy between the leaf spring and the inner surface of the case lid, which determines accuracy, can be easily increased. Wear.

[0023] Also, the part that crimps and secures the body and lid of the case is the same as the connection of case parts. Since the leaf spring can be fixed at times, the assembly process and structure are simplified.

[0024] Furthermore, pieces of magnetic material are press-fitted onto both ends of the movable magnetic material to connect them. The thing that fixes the free end of the leaf spring between the piece and the movable magnetic body is the distance between the leaf springs and The dimension between the leaf spring and the other end surface of the piece, which affects the gap accuracy, can be set with high precision, and the plate It also avoids unnecessary stress being applied to the spring, resulting in higher sensitivity and lower performance. Standardization can be achieved.

[0025] Therefore, according to the present invention, the acceleration detector can be improved in performance, manufactured easily, and reduced in cost. It is possible to achieve the effect that it is possible to simultaneously achieve the reduction.

[Brief explanation of drawings]

[Fig. 1] A schematic configuration diagram showing one embodiment of the acceleration detector of this invention.

[Figure 2] Schematic configuration diagram of another embodiment

[Figure 3] Diagram showing a conventional differential transformer type acceleration detector

[Explanation of symbols]

1, 11, 41 Acceleration detector 2, 12 Magnetic case 2-1, 12-1 Case body 2-2, 12-2 Case cover 3a, 3b, 13a, 13b, 43a, 43b Leaf spring 4, 14, 44 Movable magnetic body 5, 15 Magnetic body piece 6a, 6b, 16a, 16b, 46 Primary coil 7a, 7b, 17a, 17b, 47a, 47b Secondary coil 8, 18 Yoke c Clamping plate spring Part G Gap

Claims (4)

[Scope of utility model registration request] Claim 1: In an acceleration detector that detects acceleration by generating an output difference between secondary coils of a differential transformer by displacement of a movable magnetic body that moves in response to acceleration, the movable magnetic body is Both ends of a movable magnetic body that penetrates the primary coil and secondary coil and protrudes from the coil are supported by leaf springs, and these two leaf springs are attached to the body of the magnetic body case that covers the outer periphery of the differential transformer. An acceleration detector, characterized in that the acceleration detector is sandwiched and fixed between the end faces of the lid part of the case which are opposed to each other with a predetermined gap between the end faces of the part and both ends of the movable magnetic body in the direction of movement. 2. The acceleration detector according to claim 1, wherein the lid of the case is inserted into the opening of the body and the opening edge of the body is caulked to fix the lid to the body. 3. The acceleration according to claim 1 or 2, wherein a piece of magnetic material is coupled to both ends of the movable magnetic material in the moving direction, and the free end of the leaf spring is sandwiched and fixed between the piece and the movable magnetic material. Detector. 4. The acceleration detector according to claim 3, wherein the piece is press-fitted into a hole or a small-diameter convex portion formed on an end surface of the movable magnetic body.