JP2006080183A - Driving device for solenoid valve - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To eliminate an exclusive means for detecting the disconnection failure of a reflow diode different from the detecting means for detecting the disconnection failure of an electric field effect transistor, and to permit the detection of the disconnection failure of the reflow diode while permitting the reduction of cost, in the driving device for solenoid valve which is equipped with: the electric field effect transistor connected in series to the coil of the solenoid valve permitting even half opening control under a current having an intermediate value between ON/OFF; the reflow diode connected in parallel to the coil; and a conduction control means for controlling the conduction/interception condition of the electric field effect transistor through duty control upon the half-open control. <P>SOLUTION: The disconnection failure detecting means 52 for detecting the disconnection failure of the electric field effect transistor 46 is comprised, and the electric field effect transistor 46 is set so as to cause thermal runaway in accordance with the duty control upon the disconnection failure of the reflow diode 47. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention provides a field effect transistor connected in series to a coil of a solenoid valve that can be switched on / off and can also be controlled half-open with an intermediate current between on and off, and in parallel with the coil. And an energization control means for controlling the energization state of the field effect transistor by performing duty control on the energization / interruption state of the field effect transistor with a pulse width modulation signal during the half-opening control. The present invention relates to a valve drive device.

A field effect transistor is connected in series to the coil of the solenoid valve, and the freewheeling diode that stabilizes the intermediate current value at the time of half-open control by slowly reducing the current flowing through the coil when the energization to the coil is stopped An electromagnetic valve drive device configured to be connected in parallel to a coil is known, for example, from Patent Document 1.
Japanese National Patent Publication No. 10-504259

  In such a drive device, when a disconnection failure of the field effect transistor occurs, it becomes difficult to control the operation of the solenoid valve. Therefore, it is necessary to have a configuration that can detect the disconnection failure of the field effect transistor. Generally, a means for detecting a disconnection failure is provided. On the other hand, there is a possibility that the free-wheeling diode connected in parallel to the coil may also break, and in order to detect such a free-wheeling diode breakage, the free-wheeling diode is disconnected separately from the means for detecting the open-circuit failure of the field effect transistor. Providing a special means for detecting a failure causes an increase in cost.

  The present invention has been made in view of such circumstances, and it is not necessary to provide a dedicated means for detecting a disconnection failure of a freewheeling diode separately from a means for detecting a disconnection failure of a field effect transistor, thereby enabling cost reduction. An object of the present invention is to provide a solenoid valve drive device that can detect a disconnection failure of a return diode.

  In order to achieve the above object, the present invention provides an electric field connected in series to a coil of an electromagnetic valve that can be switched on and off and can be controlled half-open with an intermediate current between on and off. An effect transistor, a free-wheeling diode connected in parallel to the coil, and an energization control means for controlling the energization state of the field effect transistor by duty controlling the energization / cutoff state of the field effect transistor during the half-opening control. In the electromagnetic valve drive device, comprising: a disconnection failure detecting means for detecting a disconnection failure of the field effect transistor, wherein the field effect transistor is heated according to duty control of the field effect transistor when the disconnection failure of the reflux diode occurs. It is set to be destroyed.

  According to the above configuration of the present invention, when the duty control of the field effect transistor is performed in a state where the freewheeling diode is broken, the field effect transistor is thermally destroyed, so that it can be detected by the breakage failure detection means. It is not necessary to provide a disconnection failure detection means dedicated to the return diode, and it is possible to detect a disconnection failure of the return diode while enabling cost reduction.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below based on one embodiment of the present invention shown in the accompanying drawings.

  1 to 7 show an embodiment of the present invention. FIG. 1 is a brake hydraulic circuit diagram of a brake device for a passenger vehicle. FIG. 2 is a longitudinal sectional view of a normally open solenoid valve. FIG. FIG. 4 is a diagram showing a configuration of a drive device for a normally open solenoid valve, FIG. 5 is a diagram showing an example of a command signal to the normally open solenoid valve, and FIG. FIG. 7 is a diagram showing an example of the time lapse of the drive signal, voltage, operating current and temperature of the field effect transistor, and FIG. 7 is a diagram showing the guaranteed operating range of the field effect transistor.

  First, in FIG. 1, a tandem master cylinder M includes first and second output ports 1 and 2 that generate brake fluid pressure in accordance with a pedaling force applied to a brake pedal P by a vehicle driver. Fluid pressure control valve means VA and VB are interposed between the first output hydraulic pressure path 3 connected to the port 1 and the left front wheel brake BA and the right rear wheel brake BB, respectively. Hydraulic pressure control valve means VC and VD are interposed between the second output hydraulic pressure path 4 connected to the port 2 and the right front wheel brake BC and the left rear wheel brake BD, respectively.

  The hydraulic control valve means VA to VD are normally open solenoid valves individually corresponding to the left front wheel brake BA, right rear wheel brake BB, right front wheel brake BC and left rear wheel brake BD. 5A to 5D, check valves 7A to 7D connected in parallel to the normally open solenoid valves 5A to 5D, respectively, and normally closed solenoid valves 6A to 6D individually corresponding to the wheel brakes BA to BD Prepare.

  The normally open solenoid valves 5A and 5B corresponding to the first output hydraulic pressure path 3 are interposed between the first output hydraulic pressure path 3 and the left front wheel brake BA and the right rear wheel brake BB. The The normally closed solenoid valves 6A and 6B corresponding to the first output hydraulic pressure path 3 include a single first reservoir 8A corresponding to the first output hydraulic pressure path 3, a left front wheel brake BA and a right rear wheel. It is interposed between the wheel brakes BB. The first reservoir 8A is connected to the suction side of the first pump 10A through which the brake fluid can be pumped from the first reservoir 8A via the first suction valve 9A, and the discharge side of the first pump 10A is connected to the first discharge valve 11A and the first discharge valve 11A. The first output hydraulic pressure path 3 is connected to the first damper 12A.

  The normally open solenoid valves 5C and 5D corresponding to the second output hydraulic pressure path 4 are interposed between the second output hydraulic pressure path 4 and the right front wheel brake BC and the left rear wheel brake BD. Is done. The normally closed solenoid valves 6C and 6D corresponding to the second output hydraulic pressure path 4 include a single second reservoir 8B corresponding to the second output hydraulic pressure path 4, a right front wheel brake BC and a left rear wheel. It is interposed between the vehicle wheel brakes BD. A suction side of a second pump 10B capable of pumping brake fluid from the second reservoir 8B is connected to the second reservoir 8B via a second suction valve 9B, and a discharge side of the second pump 10B is connected to the second discharge valve 11B and the second reservoir 8B. It is connected to the second output hydraulic pressure path 4 via the 2 damper 12B.

  The check valves 7A to 7D are connected in parallel to the normally open solenoid valves 5A to 5D so as to allow the flow of brake fluid from the corresponding wheel brakes BA to BD to the master cylinder M.

  The operations of the hydraulic pressure control valve means VA to VD, that is, the operations of the normally open solenoid valves 5A to 5D and the normally closed solenoid valves 6A to 6D, and the operations of the first and second pumps 10A and 10B, Controlled by controller C.

  Each of the hydraulic control valve means VA to VD communicates between the master cylinder M and the wheel brakes BA to BD by the controller C and the wheel brakes BA to BD and the wheel brakes at the time of normal braking in which each wheel is not likely to be locked. Control is performed so that the reservoirs 8A and 8B are disconnected. That is, the normally closed solenoid valves 6A to 6A are closed by non-energization, and the normally open solenoid valves 5A to 5A are opened by non-energization, so that the first output port 1 of the master cylinder M The brake fluid pressure output from the valve acts on the left front wheel wheel brake BA via the normally open solenoid valve 5A and acts on the right rear wheel wheel brake BB via the normally open solenoid valve 5B. The brake hydraulic pressure output from the second output port 2 of the master cylinder M acts on the right front wheel wheel brake BC via the normally open solenoid valve 5C, and the left rear via the normally open solenoid valve 5D. It acts on the wheel brake BD for wheels.

  When the wheel is about to enter the locked state during the braking, the hydraulic control valve means corresponding to the wheel that is about to enter the locked state among the hydraulic pressure control valve means VA to VD is controlled by the controller C. The master cylinder M and the wheel brakes BA to BD are shut off, and the wheel brakes BA to BD and the reservoirs 8A and 8B are connected to each other. That is, among the normally open solenoid valves 5A to 5D, the normally open solenoid valves corresponding to the wheels that are about to enter the locked state are closed by energization, and the normally closed solenoid valves 6A to 6D are closed. Of these, the normally closed solenoid valve corresponding to the wheel is opened by energization. Thereby, a part of the brake fluid pressure of the wheel that is about to enter the locked state is absorbed by the first reservoir 8A or the second reservoir 8B, and the brake fluid pressure of the wheel that is about to enter the locked state is reduced. It will be.

  Further, when the brake fluid pressure is kept constant, each of the fluid pressure control valve means VA to VD is controlled by the controller C so that the wheel brakes BA to BD are disconnected from the master cylinder M and the reservoirs 8A and 8B. . That is, the normally open solenoid valves 5A to 5D are closed by energization, and the normally closed solenoid valves 6A to 6D are closed by deenergization. When the brake fluid pressure is further increased, the normally closed solenoid valves 6A to 6D are closed by deenergization, and the normally open solenoid valves 5A to 5D are normally opened solenoid valves 5A to 5D. By controlling the application current, the hydraulic pressure downstream of these normally open solenoid valves 5A to 5D is linearly controlled according to the application current.

  Incidentally, the first and second pumps 10A and 10B are controlled by the controller C so as to operate during the antilock brake control, and the brake fluid in the first and second reservoirs 8A and 8B is the first and second pumps. The two pumps 10A and 10B are refluxed to the master cylinder M side. Such recirculation of the brake fluid can prevent an increase in the amount of depression of the brake pedal P due to the absorption of the brake fluid into the first and second reservoirs 8A and 8B. Moreover, since the pulsations of the discharge pressures of the first and second pumps 10A and 10B are absorbed by the first and second dampers 12A and 12B, the operation feeling of the brake pedal P is not hindered by the reflux.

  Thus, during the anti-lock brake control, the normally closed solenoid valves 6A to 6D are on / off controlled by the controller C, whereas the normally open solenoid valves 5A to 5D are on / off controlled. It is also controlled by an intermediate value current between on and off, and is a normally open type configured to linearly change the hydraulic pressure on each wheel brake BA to BD side in accordance with such an intermediate value applied current. The configuration of the normally open solenoid valve 5A among the solenoid valves 5A to 5D will be described below with reference to FIG.

  In FIG. 2, the normally open electromagnetic valve 5 </ b> A includes a solenoid portion 14 that exhibits electromagnetic force and a valve portion 15 that is driven by the solenoid portion 14, and one surface 16 a of a fixed support block 16. The valve portion 15 is accommodated in the mounting hole 17 provided in the support block 16 so as to open, and the solenoid portion 14 protrudes from one surface 16 a of the support block 16.

  The valve portion 15 includes a valve housing 18 formed of a magnetic metal into a stepped cylindrical shape. The valve housing 18 is fitted into the mounting hole 17 of the support block 16. A retaining ring 19 that engages with the valve housing 18 and prevents the valve housing 18 from being detached from the mounting hole 17 is fitted to the inner surface of the mounting hole 17 near the opening end. In addition, annular seal members 20 and 21 are mounted at two positions on the outer surface of the valve housing 18 that are spaced apart in the axial direction, and between the seal members 20 and 21 between the support block 16 and the valve housing 18. An annular chamber 22 is formed.

  A cylindrical valve seat member 23 is press-fitted and fixed to the valve housing 18. A valve shaft 24 made of a non-magnetic material is slidably fitted in the valve housing 18, and an output chamber 25 is formed between one end of the valve shaft 24 and the valve seat member 23, and faces the output chamber 25. Thus, a spherical valve body 26 that can be seated on the valve seat 23 a formed on the valve seat member 23 is fixed to one end of the valve shaft 24. In addition, a return spring 27 is provided between one end of the valve shaft 24 and the valve seat member 23 to urge the valve shaft 24, that is, the valve body 26 in a direction away from the valve seat member 23.

  A filter 29 is attached to the valve housing 18 so as to be interposed between the hydraulic pressure path 28 provided in the support block 16 and connected to the first output hydraulic pressure path 3 and the valve seat member 23. A filter 30 is mounted on the outer periphery of the valve housing 18 at a portion facing the annular chamber 22, and a passage 31 for allowing the output chamber 25 to communicate with the annular chamber 22 through the filter 30 is provided in the valve housing 18. . The annular chamber 22 communicates with the wheel brake BA, and the support block 16 is provided with a hydraulic pressure path 32 that communicates the annular chamber 22 with the wheel brake BA. Further, the valve housing 18 is opened between the valve seat member 23 and the filter 29 when the pressure in the hydraulic pressure passage 28 is lower than that in the annular chamber 22, and the brake fluid in the annular chamber 22 is returned to the hydraulic pressure passage 28 side. A check valve 7A is provided.

  The solenoid unit 14 guides the movement of the armature 36 toward and away from the fixed core 35, the armature 36 that is coaxially connected to the other end of the valve shaft 24 in the valve unit 15 and faces the fixed core 35. Guide cylinder 37, a bobbin 38 surrounding the guide cylinder 37, a coil 39 wound around the bobbin 38, a magnetic path frame 40 surrounding the coil 39, and the magnetic path frame 40 and the bobbin 38. The coiled spring 41 is provided.

  The fixed core 35 is formed in a cylindrical shape, and is coaxially and integrally connected to the central portion of one end of the valve housing 18. The guide cylinder 37 is formed in a thin bottomed cylindrical shape with a hemispherical closed end at one end made of a nonmagnetic material such as stainless steel, and the distal end of the fixed core 35 is connected to the other end of the guide cylinder 37. And the other end of the guide tube 37 is fixed to the fixed core 35 by welding, for example. In addition, the guide cylinder 37 protrudes from the one surface 16 a of the support block 16 in the mounting state of the valve housing 18 in the mounting hole 17.

  The bobbin 38 has a center hole 38a through which the guide cylinder 37 is inserted and is formed of synthetic resin. A coil 39 is wound around the bobbin 38.

  The magnetic path frame 40 includes a magnetic path cylinder 42 that surrounds the bobbin 38 and the coil 39. A ring plate-like magnetic path plate 43 that abuts on the bobbin 38 is caulked and engaged with one end of the magnetic path tube 42 so that the closed end of the guide tube 37 protrudes from the center.

  On the other hand, the other end of the magnetic path cylinder 42 is integrally provided with a ring plate-like contact plate portion 42a that contacts the one end of the valve housing 18 around the fixed core 35, and this contact plate portion 42a. The base portion of the fixed core 35 is fitted to the inner periphery of the fixed core 35. The other end of the coiled spring 41 having one end abutted against the abutting plate portion 42 a is abutted against the bobbin 38.

  An armature 36 that can move toward and away from the fixed core 35 is housed in the guide cylinder 37, and one end of the valve shaft 24 that movably penetrates the fixed core 35 is coaxial with the armature 36. Abutted. By the way, the valve shaft 24 is biased in a direction away from the valve seat member 23 by the spring force of the return spring 27, and the other end of the valve shaft 24 is always in contact with the armature 36. In response to the axial movement of the armature 36, the valve shaft 24, that is, the valve body 26 also moves in the axial direction.

  That is, in a state where the magnetic attractive force toward the fixed core 35 is not acting on the armature 36, the armature 36 is in a retracted position by the spring force of the return spring 27 until it is received at one end closed portion of the guide cylinder 37. At this time, the valve body 26 is separated from the valve seat member 23, and the normally open electromagnetic valve 5A is in the valve open state. When the armature 36 is magnetically attracted to the fixed core 35 until the valve body 26 is seated on the valve seat member 23, the normally open solenoid valve 5A is closed.

  By the way, a combined force of the hydraulic pressure and the spring force of the return spring 27 acts on one end of the valve shaft 24 due to the hydraulic pressure of the output chamber 25, while an armature 36 is fixed to the other end of the valve shaft 24. The magnetic attraction force attracted to the core 35 side acts, and the valve shaft 24 is stroke-operated so that the resultant force of the fluid pressure and the spring force is balanced with the magnetic attraction force. Therefore, the magnetic attraction force for attracting the armature 36 toward the fixed core 35 is changed by controlling the energization amount to the coil 39 by the controller C so as to be an intermediate value between on and off by duty control, for example.

  On the other hand, the opposed surfaces 35 a and 36 a of the fixed core 35 and the armature 36 are formed as tapered surfaces that increase in diameter as they move away from the output chamber 25.

  When the opposing surfaces 35a and 36a of the fixed core 35 and the armature 36 are formed in a tapered surface in this way, the opposing distance between the fixed core 35 and the armature 36 (in a direction perpendicular to the tapered surface) compared to the axial stroke amount of the armature 36. The change in the suction force generated between the opposed surfaces 35a and 36a is smaller than the change in the axial stroke. Moreover, the suction force that actually acts in the axial direction is the Sin component of the suction force generated between the opposing surfaces 35a and 36a, and with respect to the change in the suction force between the opposing surfaces 35a and 36a as the taper surface angle becomes acute. The change in the suction force in the axial direction is reduced.

  As a result, as shown by the solid line in FIG. 3, the suction force between the fixed core 35 and the armature 36 can be substantially flat in the practical range between the fully closed and fully opened states in the valve portion 15. On the other hand, when the opposing surfaces of the fixed core 35 and the armature 36 are flat surfaces perpendicular to the axial direction, the opposing distance between the fixed core 35 and the armature 36 changes in proportion to the axial stroke of the valve shaft 24. Therefore, as shown by the chain line in FIG. 3, the suction force between the fixed core 35 and the armature 36 changes greatly even in the practical range.

  In this way, the normally open solenoid valve 5A is on / off controlled and can be controlled by an intermediate current between on and off in order to linearly change the hydraulic pressure on the wheel brake BA side. The open solenoid valves 5B to 5D are also configured similarly to the normally open control valve 5A. On the other hand, the normally closed solenoid valves 6A to 6D are only on / off controlled.

  In FIG. 4, in order to drive the normally open electromagnetic valve 5A, one end of the coil 39 is connected to a power source 45, and a field effect transistor (hereinafter referred to as FET) is connected between the other end of the coil 39 and the ground. 46) is interposed. A free-wheeling diode 47 is connected in parallel to the coil 39, a diode 48 and a Zener diode 49 are connected in series between the drain and gate of the FET 46, and the gate of the FET 46 is grounded via a Zener diode 50. The

  The controller C includes an energization control unit 51 connected to the gate of the FET 46 and a disconnection failure detection unit 52 connected between the parallel circuit composed of the coil 39 and the reflux diode 47 and the power supply 45.

  The energization control means 51 is connected to the gate of the FET 46, and controls the ON / OFF of the normally open solenoid valve 5 </ b> A and performs the half-open control by the intermediate current between ON / OFF. Controls energization and shutoff. Thus, the command signal for opening and closing the normally open solenoid valve 5A during the antilock brake control changes as shown in FIG. 5, for example, and when the duty is held, a constant current lower than that in the ON state is applied to the coil 39. In order to apply a current lower than that in the on state to the coil 39 when the duty is increased, the energization control means 51 repeats the increase and decrease within the predetermined width. When the duty is increased, the energization / cutoff of the FET 46 is controlled by a pulse signal by pulse width modulation.

  The disconnection failure detection means 52 detects the voltage between the coil 39 and the power supply 45, and determines that the disconnection failure of the FET 46 has occurred due to the change in the detection voltage when the disconnection failure of the field transistor 46 occurs. is there.

  By the way, when the drive signal for energizing / interrupting the FET 46 changes as shown in FIG. 6A, the voltage, operating current, and temperature of the FET 46 are as shown in FIGS. 6B, 6C, and 6D. At times t1 and t2 when the FET 46 is cut off, the back electromotive voltage generated by the coil 39 is applied to the FET 46, and the temperature of the FET 46 rises due to heat generated by the back electromotive voltage. The counter electromotive voltage increases as the current flowing through the coil 39 rapidly decreases when energization is stopped. Therefore, the reflux diode 46 is connected in parallel to the coil 39 in order to gently reduce the current flowing through the coil 39 when the energization of the coil 39 is stopped. However, when a disconnection failure of the free wheel diode 46 occurs, the function of the free wheel diode 46 becomes invalid, and when the energization is stopped, the current flowing through the coil 39 rapidly decreases and heat generation due to the back electromotive voltage increases.

As shown in FIG. 7, the operation guarantee range of the FET 46 is limited by the on-resistance limit line L1, the limit line L2 based on current limit (heat generation due to current), the limit line L3 based on thermal breakdown (current × voltage), and the overvoltage. According to the present invention, the FET 46 is energized by the energization control means 51 in order to half-open the normally open solenoid valve 5A in a state where the function of the return diode 47 is lost due to disconnection failure. The other normally open solenoid valves 5B, 5C, and 5D that are set so as to be thermally destroyed are configured in the same manner as the normally open solenoid valve 5A.

  Next, the operation of this embodiment will be described. The disconnection failure of the FET 46 connected in series to the coils 39 of the normally open solenoid valves 5A to 5D is detected by the disconnection failure detection means 52. The FET 46 is connected in parallel. Is set so as to be thermally destroyed in accordance with duty control in the event of a disconnection failure of the return diode 47 connected to, so that the normally open solenoid valves 5A to 5D are half-open controlled in a state where the return diode 47 is disconnected. Therefore, when the duty control of the FET 46 is executed, the FET 46 is thermally destroyed.

  Since this is the same event as the disconnection failure of the FET 46 for the disconnection failure detection means 52, the disconnection failure detection means 52 can detect the thermal destruction of the FET 46 based on the disconnection failure of the reflux diode 47. Therefore, it is not necessary to provide a disconnection failure detection means dedicated to the return diode 47, and it is possible to detect a disconnection failure of the return diode 47 while enabling cost reduction.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various design changes can be made without departing from the present invention described in the claims. It is.

It is a brake fluid pressure circuit diagram of a brake device of a passenger vehicle. It is a longitudinal cross-sectional view of a normally open type solenoid valve. It is a figure which shows the suction force change with respect to the stroke change of a valve shaft. It is a figure which shows the structure of the drive device of a normally open type solenoid valve. It is a figure which shows an example of the command signal to a normally open type | mold solenoid valve. It is a figure which shows an example of the time passage of the drive signal, voltage, operating current, and temperature of a field effect transistor. It is a figure which shows the operation | movement guarantee range of a field effect transistor.

Explanation of symbols

5A to 5D ... Solenoid valve 39 ... Coil 46 ... Field-effect transistor 47 ... Freewheeling diode 51 ... Energization control means 52 ... Disconnection failure detection means

Claims (1)

  A field effect transistor (46) connected in series to the coil (39) of the solenoid valve (5A to 5D) which can be switched on and off and can also be controlled half-open with an intermediate current between on and off. ), A free-wheeling diode (47) connected in parallel to the coil (39), and the current-effect state of the field-effect transistor (46) during duty-opening control by duty control. And an energization control means (51) for controlling the energization state of the field effect transistor, including a disconnection fault detection means (52) for detecting a disconnection fault of the field effect transistor (46). (46) causes thermal breakdown in response to duty control of the field effect transistor (46) when the free-wheeling diode (47) is broken. Drive of the solenoid valve, characterized in that set.

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