JPH062244U - Servo type acceleration sensor - Google Patents

Abstract

(57) [Summary] [Purpose] To prevent the elastic plate spring that swingably supports the pendulum from expanding and contracting due to temperature changes at the fixed parts on both ends, and ensuring the performance as a sensor. [Structure] A pair of elastic leaf springs 6, whose base end 6a is fixed to a pedestal 5, and whose free end 6b is connected and fixed to a connecting part 3a provided in a coil bobbin 3 of a torquer coil 2.
6 is provided. The base and the coil bobbin to which the base end and the free end of each leaf spring are fixed are made of a material having the same thermal expansion coefficient. This prevents the relative relationship between the fixing portions at both ends of the leaf spring from shifting in the surface direction of the leaf spring due to the temperature change in the ambient atmosphere.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a pendulum type servo acceleration sensor of elastic spring supporting type suitable for use as an in-vehicle accelerometer.

[0002]

[Prior art]

 The swing displacement of the pendulum according to the acceleration acting on the moving body is extracted as an electric signal, which is supplied to the Toruca coil installed on the pendulum, and the pendulum is generated by the magnetic force acting between the magnetic field generated in the Toruca coil and the permanent magnet. A servo type accelerometer which is configured to return to the position is known from, for example, Japanese Utility Model Publication No. 59-26286.

That is, conventionally, in this type of servo accelerometer, a pendulum composed of an aluminum plate and a torquer coil wound around a coil bobbin integrally assembled with the aluminum plate is arranged in parallel to the direction in which the acceleration acts. In addition, the pendulum is held by the free ends of a pair of elastic leaf springs suspended from the pedestal, and a permanent magnet is arranged in the direction orthogonal to the surface of the aluminum plate. The structure is such that an optical sensor consisting of an LED and a photodiode that confirms the position of the pendulum via the is provided.

By the way, in the above-mentioned conventional device, the aluminum plate and the torquer coil which constitute the pendulum are arranged at the free end of the elastic leaf spring in a state orthogonal to the extending direction of the leaf spring, and the permanent plate is attached to this. Since other members such as magnets are also arranged, there are many dead spaces, the entire size tends to be large, and assembly is troublesome.

Therefore, the present applicant has previously proposed an acceleration sensor capable of achieving simplification of the configuration, improvement of the assembling property, and further miniaturization of the whole according to Japanese Patent Application No. 3-163368. .

That is, in this acceleration sensor, as shown in FIG. 7, a coil bobbin 3 around which a torquer coil 2 as a pendulum 1 is wound and an aluminum plate 4 attached to the coil bobbin 3 are vertically actuated. With respect to the connecting portions 3a, 3a which are arranged in parallel with the coil bobbin 3 and project from both sides of the coil bobbin 3. The free ends 6b and 6b of the elastic leaf springs 6 and 6 are configured to be connected to each other, and these leaf springs 6 and 6 are elastically deformed in the direction in which the acceleration is applied to the free ends 6b and 6b and the free ends 6b and 6b. The pendulum 1 that has been suspended is made to perform a pendulum motion.

In such a configuration, a permanent magnet (both not shown) that cooperates with the optical sensor means for detecting the displacement of the pendulum 1 and the torquer coil 2 to generate a magnetic force is provided on both sides of the pendulum 1. The leaf springs 6 and 6 could be installed in the installation space, and the overall size could be reduced.

[0008]

[Problems to be solved by the device]

 However, the acceleration sensor having the above-mentioned structure has a problem in practical use. That is, it has been common to use a synthetic resin material as the coil bobbin 3 around which the above-mentioned Toruca coil 2 is wound, but the leaf springs 6, 6 connected to the connecting portions 3a, 3a of the coil bobbin 3 are generally used. The base 5 for holding the spring, to which the base ends 6a, 6a are fixed, is generally made of a metal material.

According to such a structure, when the ambient temperature in which this acceleration sensor is used changes, the difference between the linear expansion coefficients of both members makes it clear from (a) or (b) of FIG. The pedestal 5 or the coil bobbin 3 having the connecting portions 3a, 3a expands and contracts as shown by the arrows in the figure, and as a result, the leaf springs 6, 6 are formed into a V-shape in the plate thickness direction orthogonal to the elastically deforming direction. As a result, the spring mounting surface of the gantry 5 and the spring mounting surface of the connecting portions 3a, 3a of the coil bobbin 3 are twisted.

When such a phenomenon occurs, an error occurs in the displacement of the pendulum 1 due to the acceleration, which adversely affects the performance as a sensor, and some measures may be taken to eliminate such a problem. Is desired. In particular, such a problem has a great influence on the sensor performance when it is necessary to detect a subtle movement of the pendulum 1 as in the acceleration sensor. The useless displacement of must be wiped out.

The present invention has been made in view of such circumstances, and an object thereof is to obtain a servo type acceleration sensor that can maintain the performance as a sensor even when the temperature changes in the ambient atmosphere.

[0012]

[Means for Solving the Problems]

 In order to meet such a demand, the servo-type acceleration sensor according to the present invention has a pair of elastic members whose base end is fixed to a mount and whose free end is connected and fixed to a connecting part provided on a coil bobbin of a torquer coil. The leaf spring is provided, and the base and the coil bobbin to which the base end and the free end of each leaf spring are fixed are formed of a material having the same thermal expansion coefficient.

[0013]

[Action]

 According to the present invention, the relative positional relationship between the pedestal to which the base end of the elastic leaf spring is fixed and the coil bobbin to which the free end is connected and fixed is such that, even if heat is applied from the outside, Although it changes slightly in the plane direction of the spring, it does not change in the plate thickness direction of the leaf spring, that is, in the direction in which the leaf spring is twisted, and it is possible to prevent deterioration of sensor performance due to temperature changes.

[0014]

【Example】

 1 to 6 show an embodiment of a servo type acceleration sensor according to the present invention. In these figures, a schematic structure of the servo type acceleration sensor 10 as a whole is briefly described with reference to FIGS. 3 to 6. explain. In the above-described embodiment, the same or corresponding portions as those in FIG. 7 and the like described above are designated by the same reference numerals and detailed description thereof will be omitted.

In these drawings, reference numeral 11 is a magnet plate arranged in parallel with the pendulum 1, and a pair of permanent magnets 12, 12 are provided on the inner surface of the magnet plate at a predetermined interval in the direction in which acceleration acts. It is attached in advance. The permanent magnets 12 and 12 face the left and right side surfaces of the aluminum plate 4 with a slight gap therebetween, and their magnetic poles are opposite to each other.

Reference numeral 13 is a spacer, and the spacer 13 is provided with an LED 14 which is located between the permanent magnets 12 and 12 and serves as a light source of the optical sensor means.

Reference numeral 15 denotes a printed circuit board which is arranged so as to face the magnet plate 11 and the pendulum 1 is arranged between the magnet plate 11 and the printed circuit board 15. Necessary various electric circuit parts and wiring are provided. Reference numeral 16 denotes a yoke made of a magnetic plate material provided inside the printed circuit board 15. A window portion formed in a part of the yoke has a two-part type photo sensor which faces the LED 14 and serves as an optical sensor means. The diode 17 is provided as a light receiving element.

In FIG. 3 and the like, reference numeral 18 denotes a slit formed in the coil bobbin 3 and the aluminum plate 4 which compose the pendulum 1, and the photodiode 17 selectively detects light from the LED 14 through the slit 18. A displacement detector that detects the displacement position of the pendulum 1 is configured by the electric signal generated at 1.

In the above structure, the pendulum 1 including the torquer coil 2 and the aluminum plate 4 is supported by the leaf springs 6 and 6 to swing in the acting direction of acceleration, that is, the direction indicated by the arrow in FIGS. 3 and 5. It is designed to work dynamically. Further, in the above-described acceleration sensor 10, the magnet plate 11, the spacer 13, the yoke 16 and the printed circuit board 15 are laminated in a state where the pendulum 1 is incorporated in the internal space thereof and integrated by screws or the like. As a result, the entire system is miniaturized.

Further, in the acceleration sensor 10 described above, although not shown in the figure, an electric circuit including various resistors and a servo amplifier including a differential amplifier is used to generate the original pendulum 1 based on the electric signal obtained by the optical sensor means. A current for returning to the position is applied to the torquer coil 2, and the magnitude of acceleration can be detected by the voltage generated at both ends of the resistor connected in series with the torquer coil 2.

Here, in the acceleration sensor 10 having the above-described configuration, as shown by an imaginary line arrow in FIG. 5, one permanent magnet 12 to the aluminum plate 4, the torquer coil 2, the yoke 16, the torquer coil 2, and the aluminum plate 4 are provided. A magnetic flux loop is formed by the other permanent magnet 12 and the magnet plate 11. Then, the pendulum 1 moves in the direction of the arrow in the drawing, and the position signal generated from the optical sensor means (14, 17) changes due to the acceleration applied. When this signal change is supplied to the torquer coil 2 via the servo amplifier, a magnetic force acts between the current flowing through the torquer coil 2 and the magnetic field, and a force for returning the pendulum 1 to the original state acts. Therefore, the actual distance traveled by the pendulum 1 is extremely small. In addition, a voltage corresponding to the detected acceleration is generated at both ends of the resistor connected in series to the Toruca coil 2.

According to the present invention, in the servo type acceleration sensor 10 described above, the base end 6a is fixed and the free end 6b is fixed by the torquer coil to the mount 5 which is partially screwed to the magnet plate 11 and the like. The coil bobbin 3 and the pedestal 5 to which the base ends and the free ends of the pair of elastic leaf springs 6 and 6 that are fixedly connected to the connecting portions 3a and 3a provided on the second coil bobbin 3 are fixed. The feature is that they are made of the same material. Reference numeral 20 in the drawing denotes a pressing plate which is fixed by pressing the base end portions 6a, 6a of the leaf springs 6, 6 to the pedestal 5 and is fixed integrally to the pedestal 5 with screws 21 or the like. The holding plate 20 may also be formed of the same material as the gantry 5 described above. Reference numeral 22 in the drawing denotes a screw for fastening and fixing the free ends 6b, 6b of the leaf springs 6, 6 to the connecting portions 3a, 3a of the coil bobbin 3.

Here, it has been confirmed by experiments that PGT-G30 (polybutylene terephthalate resin containing 30% glass) or the like may be used as a material for forming the mount 5 and the coil bobbin 3 described above. However, the material is not limited to this, and other materials may be used as long as they have the same coefficient of thermal expansion.

According to this structure, the pedestal 5 and the pressing plate 20 to which the base ends 6a of the elastic leaf springs 6 and 6 are fixed and the coil bobbin 3 to which the free end 6b is fixedly connected are relatively disposed. However, even if heat is applied from the outside, it does not change in the plate thickness direction of the plate spring 6, that is, in the direction in which the plate spring 6 is twisted, although it changes slightly in the plane direction of the plate spring 6. The sensor performance can be reliably prevented from deteriorating due to temperature changes in the ambient atmosphere.

It is needless to say that the present invention is not limited to the structure of the embodiment described above, and the shape, structure, etc. of each part of the servo type acceleration sensor 10 can be appropriately modified or changed.

[0026]

[Effect of device]

 As described above, according to the servo type acceleration sensor of the present invention, a pair of elastic leaf springs whose base end is fixed to the mount and whose free end is connected and fixed to the connecting part provided on the coil bobbin of the torquer coil is provided. Since the base and the coil bobbin to which the base end and the free end of each leaf spring are fixed are made of a material having the same coefficient of thermal expansion, the base of the elastic leaf spring is formed despite the simple structure. The relative positional relationship between the pedestal whose ends are fixed and the coil bobbin whose free ends are connected and fixed varies in the plane direction of the leaf spring even if heat is applied from the outside. It does not change in the plate thickness direction of the spring, that is, in the direction in which twisting occurs in this plate spring, and it has various practically excellent effects that it is possible to reliably prevent deterioration of sensor performance due to temperature changes as in the past.

[Brief description of drawings]

FIG. 1 is a schematic view of a pendulum and an elastic plate spring supporting portion showing an embodiment of a servo-type acceleration sensor according to the present invention.

FIG. 2 is a schematic side view of FIG.

FIG. 3 is a front view of a main part for explaining a schematic configuration of the entire servo type acceleration sensor.

FIG. 4 is a side sectional view showing a configuration of a main part of FIG.

5 is a schematic plan view of a pendulum portion when FIG. 3 is viewed from the plane direction.

FIG. 6 is a schematic plan view of an elastic leaf spring portion for suspending and supporting a pendulum as seen in the plan view of FIG.

FIG. 7 is a schematic view showing a pendulum and a support portion by elastic plate springs showing a conventional example of an acceleration sensor.

8A and 8B are schematic explanatory views showing a problem when the acceleration sensor shown in FIG. 7 is subjected to a temperature change, shown in FIGS.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Pendulum 2 Toruca coil 3 Coil bobbin 3a Connection part 4 Aluminum plate 5 Frame 6 Elastic leaf spring 6a Base end part 6b Free end 10 Servo type acceleration sensor 11 Magnet plate 12 Permanent magnet 13 Spacer 14 LED 15 Printed circuit board 16 Yoke 17 Photodiode 18 Slit 20 Presser plate 21 Screw

Claims (1)

[Scope of utility model registration request] 1. A servo-type acceleration sensor that detects a displacement of a pendulum according to acceleration, supplies the detection signal to a torquer coil to drive the pendulum in the original direction, and represents acceleration by the value of this detection signal. The base end portion is fixed to the gantry, and the free end is provided with a pair of elastic leaf springs connected and fixed to a connecting portion protruding from the coil bobbin of the torquer coil. The base end portions of each elastic leaf spring are provided. A servo-type acceleration sensor, characterized in that the pedestal to which the free end is fixed and the coil bobbin are made of a material having the same thermal expansion coefficient.