Electromagnetic Actuator Drive System

Abstract

To provide an electromagnetic actuator capable of improving responsiveness by promoting a fall of current stored in a coil.SOLUTION: An actuator drive system 100 has a configuration including an electromagnetic actuator 200 and a drive circuit 110 for driving the electromagnetic actuator 200. The electromagnetic actuator comprises: a housing 202; a cylindrical drive coil 210 disposed inside the housing; a drive plunger 220 disposed inside the drive coil; a shaft 10 inserted in the drive plunger; and a lock mechanism for engaging the drive plunger with the shaft when the drive coil is excited. The drive circuit comprises: a switch (drive switch 122) for sending pulse current to the drive coil; and a Zener diode (drive side Zener diode 124) for forming a closed loop between the drive coil and the ground.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to an electromagnetic actuator drive system including an electromagnetic actuator and a drive circuit that drives the electromagnetic actuator. [Background technology]

[0002] Electromagnetic actuators are used in vehicles for parking lock mechanisms and the like. For example, the actuator disclosed in Patent Document 1 includes a driven member, a drive mechanism, a locking device, and a release mechanism. The driven member reciprocates to switch between a parking lock state in which the output shaft of the transmission is locked and an unlocked state in which the output shaft is unlocked. Patent Document 1 claims to provide an actuator that can increase the travel distance of the driven member without increasing the size of the device. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6610843 Summary of the Invention [Problem to be solved by the invention]

[0004] In the electromagnetic actuator described in Patent Document 1, a current is applied intermittently to the coil (pulse current), which causes the movable core and shaft to repeatedly engage and disengage in step with the movement of the movable core (stepping actuator).This allows the shaft to be advanced little by little, resulting in a large travel distance.

[0005] However, when current is passed through the coil and then stopped, the current remains stored in the coil, causing the falling waveform to become dull. While the stored current remains, an attractive force is generated in the movable core due to the residual magnetic field, preventing the movable core from returning to its original position. Therefore, it is necessary to wait for the stored current to be released before starting the next pulse. However, waiting for the current stored in the coil to be released makes it difficult to shorten the timing between pulses, resulting in a problem of reduced responsiveness of the electromagnetic actuator's operation.

[0006] In view of the above problems, the present invention has an object to provide an electromagnetic actuator capable of improving responsiveness by promoting the fall of the current accumulated in the coil. [Means for solving the problem]

[0007] In order to solve the above problems, a representative configuration of an actuator drive system according to the present invention is an electromagnetic actuator drive system including an electromagnetic actuator and a drive circuit that drives the electromagnetic actuator, wherein the electromagnetic actuator includes a housing, a cylindrical drive coil arranged inside the housing, a drive plunger arranged inside the drive coil, a shaft inserted into the drive plunger, and a locking mechanism that engages the drive plunger and the shaft when the drive coil is excited, and the drive circuit includes a switch that sends a pulse current to the drive coil, and a Zener diode that forms a closed loop between the drive coil and ground.

[0008] The electromagnetic actuator may further include a cylindrical release coil arranged inside the housing, a release plunger arranged inside the release coil and having a shaft inserted therethrough, and a release mechanism that releases the locking mechanism by the operation of the release plunger, and the drive circuit may include a switch that sends a pulse current to the release coil and a Zener diode that forms a closed loop between the release coil and ground.

[0009] It is preferable to provide a control circuit for controlling the operation of the drive circuit, and the control circuit gradually returns the shaft to its initial position by repeatedly turning on and off a switch that sends a pulse current to the release coil. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide an electromagnetic actuator capable of improving responsiveness by promoting the fall of the current accumulated in the coil. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a diagram illustrating the overall configuration of an electromagnetic actuator in an electromagnetic actuator drive system according to an embodiment of the present invention. [Figure 2] 5A to 5C are diagrams illustrating the operation of the electromagnetic actuator of the present embodiment. [Figure 3] 1 is a block diagram illustrating the overall configuration of a drive system according to an embodiment of the present invention. [Figure 4] FIG. 2 is a diagram illustrating the waveform of a current in a coil. [Figure 5] FIG. 10 is a diagram showing measurement data when the drive coil is operated. [Figure 6] FIG. 10 is a diagram showing measurement data when the release coil is operated. DETAILED DESCRIPTION OF THE INVENTION

[0012] Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Dimensions, materials, and other specific values ​​shown in the embodiments are merely examples for facilitating understanding of the invention and, unless otherwise specified, do not limit the present invention. In this specification and drawings, elements having substantially the same functions and configurations are designated by the same reference numerals to avoid redundant explanation, and elements not directly related to the present invention are not shown.

[0013] 1 is a diagram illustrating the overall configuration of an electromagnetic actuator 200 in an electromagnetic actuator drive system according to this embodiment (hereinafter referred to as drive system 100). The electromagnetic actuator 200, which is a component of the drive system 100 in this embodiment, delivers and retracts a shaft 10.

[0014] 1, the electromagnetic actuator 200 has a cylindrical housing 202 and housing covers 204a and 204b attached to both sides of the housing 202. The shaft 10 is inserted inside the housing 202, and a return spring 206 is housed inside the housing cover 204a.

[0015] A cylindrical drive coil 210 is disposed inside the housing 202. A drive plunger 220 for advancing the shaft 10 is disposed inside the drive coil 210. The shaft 10 is inserted into the drive plunger 220. The electromagnetic actuator 200 is also provided with a locking mechanism that engages the drive plunger 220 with the shaft 10 when the drive coil 210 is excited.

[0016] The locking mechanism includes a first tapered ring 222 and a first rolling element 224. Including It is composed. The electromagnetic actuator 200 also includes a second tapered ring 252 and a second rolling element 254 that engage with the drive plunger 220 to prevent the shaft 10 from returning when the drive plunger 220 returns. The first tapered ring 222 is disposed on the inner peripheral side of the drive plunger 220 and has a tapered shape with a diameter increasing toward the feed side of the shaft. A first rolling element 224 is disposed between the first tapered ring 222 and the shaft 10 and engages with the first tapered ring 222 and the shaft 10.

[0017] The second tapered ring 252 is disposed on the inner circumferential side of the fixed core 250 and has a tapered shape whose diameter increases toward the feed side of the shaft. and shaft 10 The first rolling element 224 and the second rolling element 254 are arranged to be engaged with the axis of the shaft 10. OrthogonalThe rollers or balls are arranged in a direction that

[0018] A cylindrical release coil 230 is disposed inside the housing 202. A release plunger 240 is disposed inside the release coil 230. The shaft 10 is also inserted through the release plunger 240. The electromagnetic actuator 200 is also provided with a release mechanism that releases the locking mechanism by the operation of the release plunger 240, and the operation of the release plunger 240 causes the shaft 10, which has been advanced by the drive plunger 220, to return to its initial position.

[0019] The release mechanism includes a third tapered ring 242 and a third rolling element 244. The third tapered ring 242 is disposed on the inner circumferential side of the release plunger 240, and has a tapered shape whose diameter increases toward the opposite side of the shaft feed side. Between the third tapered ring 242 and the shaft 10, and shaft 10 An engaging third rolling element 244 is arranged.

[0020] 2A and 2B are diagrams illustrating the operation of the electromagnetic actuator 200 of this embodiment. Fig. 2A illustrates an example of the state of the electromagnetic actuator 200 when the shaft 10 is being sent out, and Fig. 2B illustrates an example of the state of the electromagnetic actuator 200 when the shaft 10 is being returned.

[0021] In a non-excited state where no power flows through either the drive coil 210 or the release coil 230, the shaft 10 is biased in the opposite direction to the shaft feed direction by the biasing force of the return spring 206, as shown in Figure 1. In this state, the first tapered ring 222 and the first rolling element 224, the second tapered ring 252 and the second rolling element 254, and the third tapered ring and the third rolling element are all contact It is in this state. The "contact state" does not mean that the two are engaged or bitten into each other, but rather that they are lightly touching each other.

[0022] When the shaft 10 is to be fed, first, power is applied to the drive coil 210. Then, the drive plunger 220 is attracted to the fixed core 250 and moves toward the shaft feed side. Then, the first rolling element 224 is attracted to the first tapered ring 222 and the shaft 10. Engage 2(a), the shaft 10 is advanced by one step in order to suppress the relative movement of these elements by the wedge effect. When the shaft 10 is moving, the second rolling element 254 is separated from the second tapered ring 252. However, when the drive plunger 220 returns, the shaft 10 also tries to return, and the second rolling element 254 moves between the second tapered ring 252 and the shaft 10. Engage Therefore, the shaft 10 cannot return and remains at that position. Then, by supplying power intermittently to the drive coil 210 (pulse current), the shaft 10 can be advanced by any number of steps.

[0023] On the other hand, when returning the shaft 10 to its initial position, power is applied to the release coil 230. The release plunger 240 is then attracted to the fixed core 270 and moves toward the shaft feed side. When the retainer 260 is moved toward the shaft feed side together with the release plunger 240, the retainer 260 separates the first rolling element 224 from the first tapered ring 222 and separates the second rolling element 254 from the second tapered ring 252. The third rolling element 244 does not engage in the direction in which the shaft 10 returns. As a result, as shown in FIG. 2( b ), the first rolling element 224, the second rolling element 254, and the third rolling element are all disengaged. Then, the shaft 10 moves toward the opposite side of the shaft feed side due to the biasing force of the return spring 206, returning to its initial position.

[0024] Fig. 3 is a block diagram illustrating the overall configuration of the drive system 100 of this embodiment. As shown in Fig. 3, the drive system 100 of this embodiment is configured to include the electromagnetic actuator 200 described using Fig. 1 and Fig. 2, a drive circuit 110 that drives the electromagnetic actuator 200, and a control circuit 140 that controls the operation of the drive circuit 110.

[0025] 3, in the drive system 100 of this embodiment, the drive circuit 110 has a drive power circuit 120 that supplies power from the power source 102 to the drive coil 210 of the electromagnetic actuator 200. The drive power circuit 120 is provided with a drive switch 122. When a drive signal (pulse current) is sent from the control circuit 140, the drive switch 122 is in the ON state, and power is supplied from the power source 102 to the drive coil 210. When a drive signal (pulse current) is not sent from the control circuit 140, the drive switch 122 is in the OFF state.

[0026] The drive circuit 110 is also provided with a release power circuit 130 that supplies power from the power source 102 to a release coil 230 of the electromagnetic actuator 200. The release power circuit 130 is provided with a release switch 132. When a release signal (pulse current) is being sent from the control circuit 140, the release switch 132 is in an ON state, and power is supplied from the power source 102 to the release coil 230. When a release signal (pulse current) is not being sent from the control circuit 140, the release switch 132 is in an OFF state.

[0027] A feature of the driving system 100 of this embodiment is that the driving circuit 110 is provided with a free wheel diode 123 and a driving side Zener diode 124 that form a closed loop between the driving coil 210 and the ground.

[0028] The drive coil 210 and the freewheeling diode 123 are connected in parallel, and when power is supplied from the power supply 102 to the drive coil 210, no current flows through the freewheeling diode 123. The freewheeling diode 123 and the drive-side Zener diode 124 are arranged back to back. When the switch is turned off, current generated by electromagnetic induction in the drive coil 210 flows back to the drive coil 210 via the ground and is consumed in the drive-side Zener diode 124.

[0029] Similarly, a freewheeling diode 133 and a release side Zener diode 134 are provided to form a closed loop between the release coil 230 and ground.

[0030] The release coil 230 and the freewheeling diode 133 are connected in parallel, and when power is supplied to the release coil 230 from the power supply 102, no current flows through the freewheeling diode 133. The freewheeling diode 133 and the release-side Zener diode 134 are arranged back to back. When the switch is turned off, current generated by electromagnetic induction in the release coil 230 flows back to the release coil 230 via the ground and is consumed in the release-side Zener diode 134.

[0031] Figure 4 is a diagram illustrating the waveform of the current in the coil. When the drive switch 122 or the release switch 132 is turned ON, power is supplied to the drive coil 210 or the release coil 230. When the switch is turned ON, the current rises gradually with a predetermined time constant. Then, when the drive switch 122 or the release switch 132 is turned OFF, the current falls gradually as shown by the dashed curve in Figure 4.

[0032] However, if the current falls slowly as shown by the dashed curve in Figure 4, the next drive signal or release signal will not be sent until time t1 when the current has finished falling. This means that the period of the pulse current cannot be shortened, and the responsiveness of the operation of feeding or returning the shaft 10 cannot be improved.

[0033] However, as described above, the freewheeling diode 123 and the driving-side Zener diode 124 are provided to form a closed loop between the driving coil 210 and the ground, and the freewheeling diode 133 and the releasing-side Zener diode 134 are provided to form a closed loop between the release coil 230 and the ground (see FIG. 3). As a result, the current accumulated in the driving coil 210 or the releasing coil 230 when the switch is turned OFF flows back to the driving coil 210 or the releasing coil 230 and is consumed in the driving-side Zener diode 124 or the releasing-side Zener diode 134.

[0034] With the above configuration, after the switch is turned off, the current drops sharply and finishes dropping at time t2, as shown by the solid curve in Figure 4. Therefore, with the drive system 100 of this embodiment, the next drive signal or release signal can be sent at an earlier timing than with conventional electromagnetic actuators, making it possible to improve the responsiveness of the operation of sending or returning the shaft 10.

[0035] FIG. 5 shows an example of measurement data when the drive coil 210 is operated. As shown in FIG. 5(a), when the drive switch is turned on, the current rises gradually (A1 in the figure). Then, in the case where the drive circuit 110 is provided with the freewheeling diode 123 and the drive-side Zener diode 124, when the drive switch 122 is turned off, the current falls sharply (B1 in the figure). From this, it can be seen that providing the drive-side Zener diode 124 can accelerate the fall of the current. This makes it possible to shorten the period T1 of the pulse current. Note that the waveforms shown in FIG. 5 are merely examples, and both the ON time and OFF time can be further shortened, as long as they are long enough to ensure this.

[0036] 5(b), when drive switch 122 is turned ON and power is supplied to drive coil 210, drive plunger 220 moves. When drive switch 122 is turned OFF and power supply to drive coil 210 stops, drive plunger 220 stops moving and returns to its initial position (housing cover 204b side). Then, by repeatedly turning drive switch 122 ON and OFF intermittently as shown in FIG. 5(a), shaft 10 is gradually advanced as shown in FIG. 5(c).

[0037] 6A and 6B show measurement data obtained when the release coil 230 is operated, with Fig. 6A showing an example and Fig. 6B showing a comparative example. The comparative example in Fig. 6B is an example in which a single release pulse is applied to return the shaft 10 to its initial position in one go.

[0038] As shown in FIG. 6(a), when the release switch 132 is turned on, the current rises gently (A2 in the figure). Then, in the case where the drive circuit 110 is provided with the freewheeling diode 133 and the release-side Zener diode 134, when the release switch 132 is turned off, the current falls sharply (B2 in the figure). From this, it can be seen that by providing the release-side Zener diode 134, it is possible to accelerate the fall of the current even when the shaft 10 is released. This makes it possible to shorten the period T2 of the pulse current.

[0039] In addition, in FIG. 6(a), the release switch 132 is repeatedly turned on and off to gradually return the shaft 10 to its initial position. The peak value of the noise at this time was 101.3 dB. In contrast, in the comparative example shown in FIG. 6(b), in which the shaft 10 was returned to its initial position in one go, the peak value of the noise was 110.1 dB. In this way, according to the present invention, it is possible to average out the noise when returning the shaft 10, and to reduce the energy generated when the returned shaft 10 collides with the housing 202. Therefore, it is possible to reduce the collision sound (noise).

[0040] While the preferred embodiments of the present invention have been described above with reference to the accompanying drawings, it goes without saying that the present invention is not limited to such examples. It is clear that those skilled in the art can conceive of various modifications and alterations within the scope of the claims, and it is understood that such modifications and alterations also fall within the technical scope of the present invention. [Industrial Applicability]

[0041] The present invention can be used in an electromagnetic actuator drive system including an electromagnetic actuator and a drive circuit that drives the electromagnetic actuator. [Explanation of symbols]

[0042] 10... shaft, 100... drive system, 102... power supply, 110... drive circuit, 120... drive power circuit, 122... drive switch, 123... freewheeling diode, 124... drive side Zener diode, 130... release power circuit, 132... release switch, 133... freewheeling diode, 134... release side Zener diode, 140... control circuit, 200... electromagnetic actuator, 202... housing, 204a... Housing cover, 204b...housing cover, 206...return spring, 210...drive coil, 220...drive plunger, 222...first tapered ring, 224...first rolling element, 230...release coil, 240...release plunger, 242...third tapered ring, 244...third rolling element, 250...stationary core, 252...second tapered ring, 254...second rolling element, 260...retainer, 270...stationary core

Claims

[Claim 1] An electromagnetic actuator drive system including an electromagnetic actuator and a drive circuit that drives the electromagnetic actuator, The electromagnetic actuator Housing and a cylindrical drive coil disposed inside the housing; a drive plunger disposed inside the drive coil; a shaft inserted through the drive plunger; a locking mechanism that engages the drive plunger with the shaft when the drive coil is excited; a cylindrical release coil disposed inside the housing; a release plunger disposed inside the release coil and having the shaft inserted therethrough; a release mechanism that releases the lock mechanism by the operation of the release plunger; Equipped with The drive circuit a drive switch that sends a pulse current to the drive coil; a drive-side Zener diode that forms a closed loop between the drive coil and ground; a release switch that sends a pulse current to the release coil; a release side Zener diode that forms a closed loop between the release coil and ground; Equipped with The electromagnetic actuator drive system includes a control circuit that controls the operation of the drive circuit, The electromagnetic actuator drive system is characterized in that the control circuit repeatedly turns the release switch on and off intermittently, thereby gradually returning the shaft to its initial position.

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