JPH0658951A - Acceleration detector - Google Patents

Abstract

PURPOSE:To obtain an acceleration detector for detecting vertical acceleration together with the vehicle height, and an acceleration detector incorporating a vehicle height detector. CONSTITUTION:A pair of permanent magnets 181, 182 are fixed to a magnet holding member 17 set coaxially with a rotary shaft 13 which rotates depending on the variation of vehicle height and a Hall element 21 fixed to a circuit board 19 is set between the permanent magnets 181, 182. Another Hall element 20 is also fixed to the circuit board 19 and a permanent magnet 22 carried on the free end of a leaf spring 24 having the other fixed end is set in an excess space part around the rotary shaft 13 while opposing closely to the Hall element 20. The permanent magnet 22 is held by bending the tip part of the leaf spring 24 with the opposite poles being arranged on the right and left sides of the extension of the leaf spring 24, and an eddy current plate 25 is set around the permanent magnet 22.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an acceleration detecting device for detecting vertical acceleration of a vehicle body.

[0002]

2. Description of the Related Art In order to improve riding comfort and steerability of a conventional traveling vehicle, a suspension mechanism supporting the vehicle is controlled. Skyhook control is known in which a suspension mechanism is controlled so as to suppress the vertical vibration of the.

The skyhook control is, for example, that a damper mechanism is hung from a fixed point in space and the vehicle body is supported by this damper mechanism. Even if the fixed point vibrates up and down, the vibration does not affect the vehicle body. The vehicle body is held in a stationary state, and in order to execute such control in the vehicle suspension mechanism, the vertical acceleration of the vehicle is detected together with the vehicle height, and the detected result is taken into consideration. It is necessary to variably control the damping force of the suspension.

For example, when the absolute velocity on the spring of the suspension set between the wheel and the vehicle body is the same as the absolute velocity between the upper and lower sides of the spring, that is, when the vehicle body and the wheel move in opposite directions, and And the wheels move in the same direction and the speed of movement of the vehicle body is faster than the speed of movement of the wheels (when the damping force of the suspension damps the vehicle body), increase the damping force of the suspension mechanism. To do. On the contrary, when the positive and negative of the two speeds are different, that is, when the vehicle body and the wheels move in the same direction and the moving speed of the wheels is faster than the moving speed of the vehicle body (the damping force of the suspension is On the other hand, when performing the excitation action), control is performed to reduce the damping force of the suspension mechanism.

In order to perform such control, an acceleration detecting mechanism for detecting the vertical acceleration of the vehicle and a vehicle height detecting mechanism for detecting the vehicle height are required. Installing two types of detection mechanisms like
Since the structure becomes more complicated in terms of control, it is desired to integrate both such detection mechanisms into a compact size. Therefore, as disclosed in Japanese Patent Publication No. 63-503087, there is known an acceleration sensor configured by using a Hall element and a leaf spring. However, in the above-mentioned acceleration detection mechanism, the magnet for measuring the displacement amount due to the change in acceleration and the magnet for eddy current braking are set independently of each other, so that the size is inevitably increased and the cost is increased. Is a factor of. Further, since it is necessary to attach the magnet to the leaf spring to detect the acceleration, an adhesive is used to fix the magnet to the leaf spring, which is one obstacle to increase the production efficiency. Has become.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and it is possible to sufficiently simplify the structure capable of effectively performing damping force control such as skyhook control of suspension. It is a first object of the present invention to provide an acceleration detecting device having such a structure, and a second object thereof is to provide an acceleration detecting device capable of detecting a change in vehicle height as well as vertical acceleration of the vehicle body. And

[0007]

An acceleration detecting device according to the present invention is provided with a leaf spring whose one end is fixed and held so as to extend in a direction perpendicular to an acting surface of acceleration, and free movement on the opposite side thereof is provided. A permanent magnet is attached to an end of the permanent magnet, and the Hall element is fixedly set in the vicinity of a plane parallel to the direction of movement of the permanent magnet which is supported by the leaf spring. Different magnetic poles are set on the left and right sides of the line that coincides with the direction in which the spring extends and on the front and back sides, respectively, and the magnetic flux set to connect the magnetic poles is set to intersect the Hall element. Here, a member that allows an eddy current to pass is set so as to surround the permanent magnet with a surface opposite to the Hall element.

Further, a circuit board, on which an input / output circuit is set, is provided in a housing integrally mounted on the vehicle, and the hall element constituting the acceleration detecting device is mounted and set on the circuit board, and this circuit The second hall element is attached to the board and set, and the second hall element is set to a position sandwiching the second hall element so that the second hall element is rotated integrally with the rotation shaft whose rotation angle is controlled in response to changes in vehicle height. The rotary magnet device including a pair of permanent magnets is installed so that the second hall element detects the vehicle height together with the vertical acceleration of the vehicle body.

[0009]

In the acceleration detecting device constructed as described above, the permanent magnet of the acceleration detecting device is constructed by paying attention to the fact that the magnetic polarities of one permanent magnet can be magnetized in directions opposite to each other. The amount of displacement of the permanent magnet, which is displaced according to the acting acceleration, is detected by the Hall element.

Further, the Hall element constituting the acceleration detecting device is set and attached to a circuit board on which an output circuit and the like are formed, and a second Hall element is attached to the circuit board to set the second Hall element. The Hall element can be configured to detect the rotation angle of a magnet device that is composed of a pair of permanent magnets that rotate in response to changes in vehicle height, and is extremely compact in configuration, along with vertical acceleration of the vehicle body. The vehicle height is detected, and it can be effectively used as a sensor mechanism for controlling the damping force of the suspension mechanism supporting the vehicle body.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a cross-sectional structure of a vehicle height detection mechanism having a built-in acceleration detection mechanism.
Although not shown in detail, it is attached to a vehicle body supported by wheels via a suspension mechanism.

A bearing mechanism 12 is formed in the central portion of the housing 11 such that the axis line is set horizontally, and the bearing mechanism 12 holds the rotary shaft 13.
The rotating shaft 13 is rotatably assembled with the washer 14 and the circlip 15 restraining the movement in the thrust direction.

Although not shown in the drawing, the end of the rotary shaft 13 is, for example, the other end of the arm connected to the axle, and the other end of the rotary shaft is the rotary shaft.
The rotation shaft 13 is rotated by an arm which is coupled to the wheel 13 and rotates with a change in the distance between the wheel and the vehicle body, that is, with a change in the vehicle height. That is, the rotating shaft 13
Is rotated according to the change of the vehicle height, and the relative relationship between the rotation angle of the rotation shaft and the vehicle height is set.

A magnet mechanism 16 is set at the end of the rotary shaft 13. The magnet mechanism 16 includes a magnet holding member 17 having a cylindrical stepped hole coaxial with the rotary shaft 13 and a magnet. The holding member 17 is composed of a pair of permanent magnets 181 and 182 set corresponding to the inner surface of the cylinder. The magnets 181 and 182 have different magnetic poles facing each other with the axis of the rotary shaft 13 in between. It That is, one of the facing surfaces of the pair of permanent magnets 181 and 182 is magnetized so that one of them is set to the N pole and the other is set to the S pole, and they are attached to the magnet holding member 17 by adhesion or the like. .

A circuit board 19 is set in the housing 11 so that the magnet holding members 17 are set at predetermined intervals. This circuit board 19 is placed on a three-point seat (not shown) formed in the housing 11 and positioned by a tamping screw or heat staking, and fixed so that a vertical surface is set with respect to the vehicle body. Has been done.

On the same surface of the circuit board 19, a second Hall element 21 for detecting a vehicle height is attached together with a chip-type first Hall element 20 for detecting acceleration. The Hall element 21 is set between a pair of permanent magnets 181 and 182 that form the magnet mechanism 16, and the magnetic flux between the permanent magnets 181 and 182 passes through the second Hall element 21 and is set. To do.

A permanent magnet 22 is provided close to the first Hall element 20.
Is set, and the first Hall element 20 is placed so as to face the center of the surface of the permanent magnet 22 that faces the circuit board 19.
Is positioned and fixed. The permanent magnet 22 is
As shown in FIG. 2, the holder 23 is mounted and set on the other end of the leaf spring 24, which has one end clamped and held, and which is free to move. It is attached and fixed using.

Specifically, as shown in FIG. 2B, the tip end of the leaf spring 24 is bent so as to surround the outer circumference of the permanent magnet 22, and the tip end of the leaf spring 24 is the base of the bent portion. The permanent magnet 22 is attached to and held at the free end of the leaf spring 24 by being overlapped with the end portion and coupled by welding or the like.

Here, the leaf spring 24 is set so as to bend in a direction parallel to the surface of the circuit board 19, that is, in a direction perpendicular to the vehicle body, and the permanent magnet 22 moves along with the vertical movement of the vehicle body. The displacement amount is set to move along the surface of the circuit board 19, and the displacement amount corresponds to the vertical acceleration of the vehicle body. The permanent magnet 22 held in this manner has N and S poles on the left and right of a boundary line (shown by a broken line in FIG. 2A) that coincides with the extending direction of the leaf spring 24, and the front and back surfaces are set. It is magnetized so that the polarity is reversed.

An eddy current plate made of pure aluminum or copper is held on the circuit board 19 so as to surround the outer periphery of the permanent magnet 22 held by the leaf spring 24 at a predetermined interval. 25 is set.

The output circuit as shown in FIG. 3 is formed on the circuit board 19 which holds the permanent magnet 22 together with the first hall element 20 and the second hall element 21 in this way. This circuit includes a constant current circuit 51, and amplifier circuits 52 and 53 for amplifying the Hall voltages of the first and second Hall elements 20 and 21, respectively.
Output circuits 54 and 55 supplied with outputs from 52 and 53
And output V from these output circuits 54 and 55
It has terminals 56 and 57 for outputting out1 and Vout2, respectively.

The output terminal from the circuit board 19 is connected to the lead wire 26 shown in FIG. 1, and the lead wire 26 is press-fitted into the rubber plug 27 to form a waterproof structure with the housing 11. I am trying to configure it. Further, a space between the rotary shaft 13 and the housing 11 is waterproofed by an oil seal 28.

FIG. 4 shows the structure of the mounting portion of the second Hall element 21.
The Hall element 21 is configured so that its magnetic sensitive point is held at the height position of the pair of magnets 181 and 182 on the central axis of the rotary shaft 13 by the holder 28 set on the surface of the circuit board 19. .

In the acceleration and vehicle height detecting device constructed as described above, the rotary shaft 13 is connected to an arm member that rotates in response to a change in vehicle height, and the change in vehicle height, that is, the distance between the axle and the vehicle body is detected. The rotating shaft 13 is rotated by the arm that is rotated according to the change.

As the rotating shaft 13 rotates, the pair of permanent magnets 181 and 182 rotate together with the rotating shaft around the second Hall element 21 together with the magnet holding member 17, and as shown in FIG. The magnetic field direction with respect to the magnetically sensitive surface of changes the Hall output voltage of the Hall element 21.

FIG. 6 shows the state of the change in the Hall voltage due to the change in the magnetic field direction. For example, the Hall element is rotated while the rotation angle of the rotary shaft 13 rotates from -90 ° to + 90 °.
The output voltage of 21 is -Va to + Va as shown in the first equation.
It changes continuously on the sine wave. Vh = Va · sin θ (1) Then, the output voltage Vh from the Hall element 21 is as shown in FIG.
The desired output voltage characteristic is converted by the amplifier circuit 53 and the output circuit 55 shown in FIG.

On the other hand, the permanent magnet 22 held by the leaf spring 24 is displaced in accordance with the vertical acceleration of the vehicle, and this displacement amount is generated by the magnetic fluxes directed in the opposite directions toward the Hall element 20. The Hall output voltage as shown in FIG. 7 is detected.

At this time, the amplitude of the leaf spring 24 is increased as shown in FIG. 8 when the resonance frequency is approached even if the acceleration is constant. In order to suppress such a situation, the eddy current plate 25 is adapted to use the magnetic flux of the surface of the permanent magnet 22 on the side opposite to the hall element 20 to apply braking using the eddy current action.

In the characteristics required for the skyhook control that actually controls the damping force of the vehicle suspension mechanism,
Since the vertical vibration exists in the vicinity of 0.5 Hz to 20 Hz, the plate thickness (= 0.2 mm) and length (= 16) of the leaf spring 24 are set so that the vibration frequency is set in the vicinity of 80 Hz.
mm), width (= 6 mm), and the shape of the permanent magnet 22 (7 mm x
4mm x 10mm, weight = 21g)
The output error in the range of 0.5 Hz to 20 Hz can be suppressed to "± 10%" or less.

If a low-pass filter is set for the output circuit 54 to which the output of the Hall element 20 shown in FIG. 3 is supplied, it is possible to suppress the output of unnecessary signals in the high frequency region.

From the above, the permanent magnet 24 corresponding to the first Hall element 20 is displaced in the desired frequency range in accordance with the vertical acceleration, and the displacement amount corresponding to this acceleration is determined by the Hall element 20. It is converted into a Hall voltage and converted into a desired output voltage characteristic by the amplifier circuit 52 and the output circuit 54.

According to the apparatus constructed as described above, one permanent magnet 22 is provided as compared with the conventional example in which the displacement amount magnet and the eddy current braking magnet are set independently for acceleration detection.
It is possible to achieve the effect in terms of both cost reduction and downsizing.

When the permanent magnet is bonded to both sides of the leaf spring, positioning is difficult, and it takes time to cure after bonding, which is a factor of lowering production efficiency. . However, FIG. 2 (B)
As shown in Fig. 4, one end of the leaf spring 24 is bent so as to surround the permanent magnet 22, and the permanent magnet 22 is held and fixed at this portion. Can be abolished.

Further, the holder 23 of the leaf spring 24 and the eddy current plate 25 can be installed in an extra space around the rotary shaft 13 for detecting the vehicle height in the housing 11 having a rectangular parallelepiped shape, for example. Further, since the circuit portion required for the vehicle height detection mechanism and the circuit portion required for the acceleration detection mechanism can be configured to be shared by one circuit board 19, the first and second circuits are further provided. Hall element
Since the power supply circuit can be shared for 20 and 21, the structure that shares the vehicle height detection mechanism and the acceleration detection mechanism can be effectively downsized and manufactured at low cost.

The eddy current plate 25 is installed so as to surround the permanent magnet 22 so as not to exceed the stress limit of the plate spring 24. However, the plate spring 24 surrounds the permanent magnet 22 to cover it. As a result, even if the permanent magnet 22 collides with the eddy current plate 25, the permanent magnet 22 can be reliably protected from damage.

[0036]

As described above, in the acceleration detecting device according to the present invention, the permanent magnet or the like that is displaced in accordance with the vertical acceleration of the vehicle body can be constructed extremely compactly, and the reliability is high. In this state, the acceleration acting on the vehicle body is detected. Since such an acceleration detecting mechanism can be compactly housed in an extra space around the vehicle height detecting mechanism, the vehicle height detecting mechanism including the acceleration detecting mechanism can be miniaturized. Therefore, a vehicle height and acceleration detection sensor for controlling the damping force of the suspension mechanism of the vehicle can be effectively configured.

[Brief description of drawings]

FIG. 1 is a cross-sectional configuration diagram illustrating a vehicle height detection device including an acceleration detection device according to an embodiment of the present invention.

FIG. 2A is a perspective view showing a permanent magnet holding mechanism portion of the acceleration detecting mechanism in the above embodiment, and FIG.

FIG. 3 is a diagram illustrating a circuit unit set on a circuit board.

FIG. 4 is a diagram illustrating a mounting portion of a hall element for vehicle height detection.

FIG. 5 is a diagram for explaining the configurations of the permanent magnet and the Hall element portion in the same manner.

FIG. 6 is a diagram showing an output voltage characteristic of a hall element of a vehicle height detection section.

FIG. 7 is a diagram showing output characteristics of an acceleration detecting Hall element.

FIG. 8 is a diagram for explaining a resonance frequency state.

[Explanation of symbols]

11 ... Housing, 12 ... Bearing part, 13 ... Rotating shaft, 16 ... Magnet mechanism, 17 ... Magnet holding member, 181, 182 ... Permanent magnet (pair), 19 ... Circuit board, 20, 21 ... First and second Hall element, 22 ... Permanent magnet, 23 ... Holder, 24 ... Leaf spring, 25 ...
Eddy current plate.

Claims (4)

[Claims] 1. A leaf spring whose one end is fixed and held so as to extend in a direction perpendicular to a surface on which acceleration is applied, and a permanent magnet which is attached and set to a free-moving end opposite to the fixed end of the leaf spring. And is fixedly set close to a plane of the permanent magnet that is supported by the leaf spring and parallel to the direction of movement, and changes in the magnetic flux generated by the permanent magnet is converted into an electrical signal and output. A Hall element, and the permanent magnet has different magnetic poles set on the left and right sides and front and back sides of a line that coincides with the extending direction of the leaf spring that supports the permanent magnet, and connects the magnetic poles. An acceleration detecting device characterized in that the magnetic flux thus set is set so as to cross the Hall element. 2. The acceleration detecting device according to claim 1, further comprising a member that allows an eddy current set on a surface of the permanent magnet opposite to the Hall element to pass therethrough. 3. A free end portion of the leaf spring is bent so as to surround the permanent magnet, and a tip end portion of the leaf spring is joined to a bent base end portion of the bent leaf spring. The acceleration detecting device according to claim 1, wherein the permanent magnet is held and set at the tip of the leaf spring. 4. A leaf spring having one end fixed and held so as to extend in a direction perpendicular to a vertical acceleration acting surface of a vehicle, and a free movement end opposite to the fixed end of the leaf spring. A permanent magnet, which is attached and set such that different magnetic poles are set on the left and right with a line that coincides with the extending direction of the leaf spring as a boundary, and an input / output circuit set on a housing integrally attached to the vehicle. And the magnetic flux generated by the permanent magnet, which is attached to the circuit board and is fixedly set close to a plane of the permanent magnet that is supported by the leaf spring and parallel to the moving direction. The first Hall element that is made to intersect with each other, the rotation shaft whose rotation angle is controlled according to the change of the vehicle height, and the rotation shaft are set so as to be integrally rotated. To have different magnetic poles A rotary magnet device configured by a pair of permanent magnets that are set, and a pair of permanent magnets that are attached to the circuit board and that configure the rotary magnet device, are set at a position that matches the rotation center axis of the rotary shaft. And a second Hall element set such that magnetic fluxes set between the pair of permanent magnets intersect with each other, the first Hall element being a signal corresponding to vertical acceleration of the vehicle. Is detected and a signal corresponding to a change in vehicle height is detected from the second hall element.