JPH077026U - Position detector - Google Patents

Abstract

(57) [Abstract] [Purpose] To improve the detection accuracy of a position detection device consisting of a permanent magnet and a reed switch. [Structure] Two reed switches 19a and 19b are connected in series as one set, and the reed switches 19a and 19b are connected in series.
19b are arranged so as to be displaced from each other in the moving direction of the permanent magnet 18 so as to open and close sequentially within a range in which both are closed by the permanent magnet 18.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an improvement of a position detecting device including a permanent magnet and a reed switch opened and closed by the permanent magnet.

[0002]

[Prior art]

 As a position detecting device similar to the one described above, for example, one implemented as a position detecting device for a damping force adjusting actuator in a damping force adjusting type shock absorber is shown in Japanese Utility Model Application Publication No. 46269. There is.

In this position detecting device, the output shaft of the damping force adjusting actuator is projected upward from the actuator, and one element of the position detecting sensor is provided on the side surface of the protruding portion of the output shaft. A permanent magnet is attached.

Further, a reed switch, which is the other element of the sensor, is fixedly arranged on the case of the damping force adjusting actuator within the moving range of the permanent magnet, and one set of each of these is used as a permanent switch. A position detecting sensor including a magnet and a reed switch constitutes a position detecting device for the damping force adjusting actuator.

[0005]

[Problems to be solved by the device]

 As described above, in the conventional position detecting device of this type, one reed switch is made to correspond to one permanent magnet, and one reed switch is opened / closed by this permanent magnet to thereby open / close the reed switch. Closing is used as a detection signal for position control.

However, in general, the range in which the reed switch is kept in the closed state due to the relative movement of the reed switch and the permanent magnet, that is, the sensitive range of the reed switch to the permanent magnet, is such as in the photointerrupter type It is much wider than other sensors, and therefore, although this kind of position detection device consisting of a permanent magnet and reed switch is advantageous in terms of cost, it is not suitable for accurate position detection. There was a problem.

Therefore, it is an object of the present invention to provide an improved position detecting device of this type capable of performing highly accurate position detection using a permanent magnet and a reed switch.

[0008]

[Means for Solving the Problems]

 According to the present invention, at least the reed switches are connected in series as a set, and the reed switches are sequentially opened and closed within a range in which both are closed by a permanent magnet. Thus, it is achieved by displacing the permanent magnets in the moving direction of the permanent magnets.

[0009]

[Action]

 That is, with the above-described configuration, one reed switch is closed first by the permanent magnet according to the relative movement of the reed switch and the permanent magnet, and then a time delay occurs before the reed switch is opened. The other reed switch is closed with.

On the other hand, when the reed switch is opened, the lead switch closed earlier is opened first, and then the other reed switch is opened with a time delay.

As a result, the range in which both reed switches are kept closed by the permanent magnet is narrower than the range in which each reed switch is kept closed individually. The range in which is closed can be appropriately selected depending on the deviation amount of each reed switch.

Therefore, by connecting both reed switches in series, the detection signal is output only in a narrow range in which these reed switches are closed together, and the position detection accuracy is improved.

[0013]

【Example】

 1 and 2 show an embodiment in which a position detecting device according to the present invention is applied to a damping force adjusting actuator of a damping force adjusting type shock absorber. The damping force adjusting actuator 1 is shown in FIG. A pair of mounting brackets 3a and 3b are provided on the outer peripheral surface of the case 2 so as to face each other.

On the other hand, a bracket 6 sandwiched between a step portion 4 a and a nut 5 is attached to the piston rod 4 on the damping force adjustable shock absorber (not shown) side.

The damping force adjusting actuator 1 is fixed to the damping force adjusting shock absorber side bracket 6 by fixing the pair of mounting brackets 3a and 3b to the bracket 6 with screws 7a and 7b, respectively. There is.

At the center of the case 2 of the damping force adjusting actuator 1, there are a bearing 8 attached to the upper surface portion 2a of the case 2 and a bearing 10 attached to the bottom surface portion 2b via a guide bush 9. An output shaft 11 is rotatably supported therethrough.

The output shaft 11 is accommodated in the piston rod 4 of the damping force adjustable shock absorber while absorbing the axial misalignment through a tongue and groove type joint 12 that is loosely inserted through the guide bush 9. It is also connected to the control rod 13 for adjusting the damping force.

A rotor 15 magnetized via a magnet bush 14 is integrally attached to the outer circumference of the output shaft 11, and the rotor 15 is surrounded by two stages of solenoid coils 16 and 17 on the stator side. Are arranged in the case 2.

The solenoid coils 16 and 17 are configured such that coil bobbins 16b and 17b, which are wound coils 16a and 17a, are housed in yokes 16c and 17c, and these solenoid coils 16 and 17 are vertically stacked. It is fixed at the inner circumference of the case 2 by holding it down with the case 2.

Thus, the rotor 15 and the solenoid coils 16, 17 on the stator side constitute the damping force adjusting actuator 1 as a PM type stepping motor.

On the other hand, in order to regulate the operating position of the stepping motor, it is usually necessary to initialize it. For example, it may be possible to limit the angle with a mechanical stopper or the like, but with a mechanical stopper, durability and collision noise are problems. Become.

Therefore, a position detecting device for detecting the operating position of the rotor 15 and automatically controlling the stop position of the stepping motor is provided.

In this embodiment, the position detecting device is a switching type position detecting sensor 20 including one permanent magnet 18 and two reed switches 19a and 19b as shown in FIG. It is composed of.

The permanent magnet 18, which is one element of the position detecting sensor 20, is attached to the lower surface of the rotor 15 of the damping force adjusting actuator 1 in a state of being molded with the molding material 18a as shown in FIG. .

Further, a concave portion 2c formed by bulging the bottom portion 2b downward is formed on the bottom portion 2b of the case 2 facing a part of the movement trajectory of the permanent magnet 18, and the concave portion is formed. As can be seen in FIG. 2 located in 2c, it houses two reed switches 19a, 19b which are the other elements of the position detecting sensor 20.

In this case, in the embodiment, the reed switches 19a and 19b are moved in the moving direction of the permanent magnet 18 so that both of them are sequentially opened and closed within a range in which both are closed by the permanent magnet 18. The permanent magnet 18 and the lead switches 19a and 19b constitute a position detecting sensor 20 for detecting the operating position of the rotor 15.

FIG. 3 shows an example of a detection circuit of the damping force adjusting actuator 1 having the above-mentioned configuration. The stator side solenoid coils 16 and 17 are bipolar drive of the controller 21 provided in the driver's seat. The reed switches 19a and 19b of the position detecting sensor 20 are also connected to the circuit 22 and are also connected to the detection circuit 23 of the controller 21 in a state where they are connected in series.

Thus, when a command signal is given to the bipolar drive circuit 22 of the controller 21 by detecting a change in the vibration state of the running vehicle or manually, a current flows through the solenoid coils 16 and 17 and the solenoids concerned. The coils 16 and 17 are excited and the polarities of the solenoid coils 16 and 17 are alternately switched.

On the other hand, the solenoid coils 16 and 17 act on the rotor 15 to move the rotor 15 step by step according to the switching of the polarities of the solenoid coils 16 and 17, for example, in a clockwise direction by a predetermined number of steps. When the rotor 15 is advanced, the rotation of the rotor 15 is transmitted from the output shaft 11 through the joint 12 to the control rod 13 of the damping force adjustable shock absorber.

When the rotor 15 advances by a predetermined number of steps, the switching of the polarities of the solenoid coils 16 and 17 is completed. At this time, for example, if the solenoid coil 16 is kept in an excited state as a reference point. The rotor 15 is initialized and stopped at that position, and the damping force generated by the damping force adjustable shock absorber is adjusted to, for example, a predetermined high damping force value.

If an opposite polarity switching signal is given to the solenoid coils 16 and 17 through the bipolar drive circuit 22, the rotor 15 advances counterclockwise step by step by a predetermined number of steps, the same as above. Adjust the damping force generated by the damping force adjustable shock absorber to a low damping force value.

However, even if the rotational position of the rotor 15 is controlled as described above, there are cases where the rotor 15 does not move, stops halfway, or stops excessively for some reason. Conceivable.

In this case, in the former case, the permanent magnet 18 provided on the rotor 15 faces the reed switches 19a and 19b on the case 2 side, and the reed switches 19a and 19b cannot be closed together. Further, in the latter case, at least the reed switch 19a is opened again after both the reed switches 19a and 19b are closed once.

Therefore, in order to detect this, in the present embodiment, when the reed switches 19a and 19b are both closed and a detection signal is not output even if a command signal is given to the bipolar drive circuit 22, an automatic detection signal is output. When the detection signal disappears after the reed switches 19a and 19b are both closed to output the detection signal, the bipolar circuit 22 is reversed. The controller 21 is configured to give a command signal.

With this, while monitoring the rotational position of the rotor 15 by simultaneously closing the reed switches 19a and 19b, while confirming the operation error of the rotor 15 and the advance angle to the predetermined position, the damping force adjustment type shock The damping force generated by the absorber will be adjusted to the desired value.

Moreover, in the above description, the permanent magnet 18 first faces the reed switch 19a as the rotor 15 is driven to rotate, and as shown in FIG. 4, the permanent magnet 18 closes the reed switch 19a first. (On)

Subsequently, before the permanent magnet 18 passes the portion of the reed switch 19a and opens it, the permanent magnet 18 faces the reed switch 19a and the other reed switch 19b with a time delay, and both reed switches 19a , 19b are closed at the same time.

On the other hand, when the permanent magnet 18 passes through the closed reed switches 19a and 19b to open them, first, the permanent magnet 18 first opens the closed reed switch 19a. Pass it open and then, with a time delay, open the part of the other reed switch 19b too.

Therefore, the range in which both the reed switches 19a and 19b are kept closed by the permanent magnet 18 is in the range from the closing of the reed switch 19a to the opening of the reed switch 19b. It is only the amount obtained by subtracting the time delay between closing and opening of 19b, which is narrower than the range in which both reed switches 19a and 19b are individually closed.

Moreover, the range in which both the reed switches 19a and 19b are closed can be adjusted arbitrarily by appropriately selecting the deviation amount of the respective reed switches 19a and 19b.

Thus, the detection signal output by closing both reed switches 19a and 19b connected in series is limited to the above narrow range, and the position detection accuracy is significantly improved compared to the conventional one.

Therefore, the operating position of the rotor 15 monitored by the detection signals from both the reed switches 19a and 19b becomes extremely accurate, and the damping force generated in the damping force adjustable shock absorber is always desired with high precision. It will be adjusted to the value of.

In the above embodiment, one permanent magnet 18 and two reed switches 19a and 19b are combined to form a set of position detecting sensors 20. On the other hand, the two reed switches 19a and 19b are arranged so as to be displaced from each other.

However, it is not always necessary to do so, and for example, two permanent magnets 18 and two reed switches 19 a and 19 b, which are the same as each other, constitute one set of position detection sensors 20, and each of them is provided with a position detection sensor 20. Even if the reed switches 19a and 19b are arranged so that their relative positions are displaced from each other with respect to the permanent magnet 18, it is apparent that the position detection accuracy can be remarkably improved in the same manner.

Further, as described above, instead of detecting the operating position of the rotor 15 by a set of position detecting sensors 20, a plurality of sets of permanent magnets 18 and reed switches 19a, 19b are provided and detected by them. Needless to say, multi-position control can be performed with high accuracy in the same manner by sequentially outputting signals.

[0046]

[Effect of device]

 As described above, according to this invention, the position detection accuracy can be remarkably improved as compared with the conventional one by the extremely simple structure.

Further, since it becomes possible to detect the angle in one step or less in the stepping motor, it becomes possible to correct the operating angle of the output shaft in the step motor using this detection signal.

[Brief description of drawings]

FIG. 1 is a vertical sectional front view showing an embodiment of a damping force adjusting actuator having a position detecting device according to the present invention.

FIG. 2 is a schematic diagram showing a configuration example of a position detection device.

FIG. 3 is a circuit diagram showing an example of a detection circuit.

FIG. 4 is an explanatory diagram showing an operating state of the position detection device.

[Explanation of symbols]

 2 case 15 rotor 18 permanent magnet 19a, 19b reed switch

Claims (1)

[Scope of utility model registration request] 1. A position detecting sensor comprising a permanent magnet and a reed switch opened and closed by the permanent magnet, wherein at least two reed switches are connected in series, and both reed switches are permanently connected. A position detecting device, which is arranged so as to be displaced in the moving direction of the permanent magnet so as to be sequentially opened and closed within a range of being closed by the magnets.