JP2000179506A - Solenoid valve having function of fluid pressure vibration detecting sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To markedly simplify a system and to reduce a cost, by providing a vibration detecting element for receiving a fluid pressure in a flow path through a valve element, when the flow path is opened, and converting the fluid pressure into an electric signal. SOLUTION: A valve element 4d always abuts to a piezoelectric element 11 by a spring 4f in a housing 4c, and the valve element 4d is moved leftward to close an inflow port 4a when a current flows in a solenoid 4g in the periphery of the housing 4c. When vibration is generated in a brake fluid when the inflow port 4a is opened, the valve element 4d is vibrated to detect the vibration by the piezoelectric element 11. When antilock control is started, and a current flows in the solenoid 4g, the valve element 4d and the piezoelectric element 11 are separated and the piezoelectric element 11 stops detecting vibration of the valve element 4d. Accordingly, necessity for providing in each wheel a vibration sensor used for impeding judder and creep grown is eliminated, so that a system can be markedly simplified.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solenoid valve having a function of detecting a hydraulic vibration in a hydraulic circuit, and more particularly to a solenoid valve having a function of actively detecting and damping the vibration of a disc brake. The hydraulic vibration detection sensor function is suitable for detecting unpleasant vibrations (judder, brake squeal) that occur at the same time, or detecting creep groan (so-called goo noise) generated when a vehicle with an automatic transmission creeps. The present invention relates to a solenoid valve having the same.

[0002]

2. Description of the Related Art When a braking force is generated by a brake device, the sliding surface of a disk rotor may vary in thickness (uneven thickness) due to frictional heat or the like during braking, and this variation in thickness may occur during braking. It causes abnormal vibration (judder) and brake squeal. This is because, when the disk rotor is uneven in thickness, a brake torque fluctuation that is directly proportional to the rotation speed of the disk rotor occurs during braking, and a brake hydraulic pressure fluctuation occurs accordingly. on the other hand,
The vehicle body and the steering system have eigenvalues (resonant frequencies). For this reason, when the frequency of the above-mentioned brake fluid pressure fluctuation matches the eigenvalue (resonance frequency) of the vehicle body and the steering diameter due to a change in vehicle speed, a resonance phenomenon occurs,
The vibration is amplified and becomes abnormal vibration (judder).

In addition, separately from the above, in an automatic transmission type vehicle equipped with a brake device for operating the master cylinder by boosting using the fluid pressure of a fluid pressure source, the traveling range of the automatic transmission (the creep traveling state) When the vehicle is stopped and held in step (1), the driver often unconsciously loosens the pedal effort. In such a case, if the pedal force is loosened and the balance between the driving torque and the braking torque is almost at a limit, a stick-slip phenomenon occurs between the pad and the disk rotor, and a so-called goo noise (creep groon) is generated, and the driver is instructed. There is a problem of giving discomfort.

[0004] Judder and brake squeals as described above,
Alternatively, a technique disclosed in Japanese Patent Application Laid-Open No. 9-22103 is disclosed as a technique for preventing vibration that causes a creep groon or the like. However, since this device uses a microphone provided on each wheel or a vibration sensor attached to a brake pad as a judder or brake noise detecting means, for example, in the case of detection by a microphone, the problem of S / N ( In practice, it is difficult to accurately detect the location and level of the occurrence of the brake noise from the separation from background noise and disturbance noise (brake noise of another vehicle, external noise (sound equivalent to brake noise)). In the vibration detection by the sensor, when the pad needs to be replaced due to wear or the like, the sensor must be replaced every time the pad is replaced, which is expensive, and since the pad becomes hot during braking, high temperature compensation is required. Type of vibration sensor is required, which increases the cost. Kicking for, only the sensor or the like are required number of wheels, increasing the number of parts, leading to increase in cost.

Therefore, the present invention focuses on a hold valve for antilock control, which is standard equipment in recent vehicles, and improves this hold valve so that a valve element in the valve is opened when a flow path is open. It is an object of the present invention to solve the above-mentioned problem by making it possible to detect the hydraulic vibration of the flow path via the flow path. The electromagnetic valve according to the present invention is configured such that the vibration of the valve element can be detected by the vibration sensor in contact with the valve element, so that the system can be compared with a case where a vibration sensor is provided for each wheel. Can be greatly simplified, and the cost can be significantly reduced.

[0006]

For this reason, the technical solution adopted by the present invention is an electromagnetic valve which is disposed in a fluid circuit and closes the flow passage by moving a valve element. An electromagnetic valve having a hydraulic vibration detection sensor function, comprising: a vibration detection element that receives a liquid pressure in a flow path via a valve element and converts it into an electric signal.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is an overall configuration diagram relating to a brake fluid pressure control device employing this solenoid valve, and FIG. 2 is an electromagnetic device incorporating a vibration sensor. FIG. 3 is a cross-sectional view of a solenoid valve incorporating a vibration sensor and a detected vibration waveform diagram, and FIG. 4 (a) and (b) are judder prevention diagrams. Control flowchart for FIG. 5,
(A) and (b) are a flowchart for detecting a creep grown generation start fluid pressure and a creep grone disappearing fluid pressure, and a flowchart for releasing the brake fluid pressure from the creep grown occurrence start fluid pressure to the creep grone disappearing fluid pressure.
FIG. 6 is a hysteresis diagram showing how the creep grone disappears. Although the figure shows a brake piping diagram for one wheel in the case of independent four wheels, it is needless to say that the present invention can be applied to two systems and three systems of brake piping.

In FIG. 1, 1 is a brake pedal as a brake operating member, 2 is a vacuum booster as a brake booster, 3 is a master cylinder (M / C),
Reference numeral 4 denotes a valve using the electromagnetic valve according to the present invention as a hold valve (hereinafter referred to as a hold valve), 5 is a decay valve, 6 is a wheel cylinder (W / C), 7 is a hydraulic oscillation device, 8 is a reservoir, and 9 is a reservoir. The pump, 10 is a wheel speed sensor for detecting wheel speed, 11 is a vibration sensor integrated with a hold valve, 12 is a stroke sensor for the piston in the reservoir 8, and 13 is an electronic control unit (ECU).
And a pump driving motor (not shown), a hold valve 4, a decay valve 5, a hydraulic oscillating device 7, a wheel speed sensor 10, a vibration sensor 11, and a stroke sensor 12.
Is an electronic control unit (ECU) using the electric signal path shown in the figure.
13 is electrically connected. The brake booster and the master cylinder have the same configuration as the conventionally known ones,
Members other than a hold valve 4, a hydraulic oscillating device 7, and a reservoir 8, which will be described later, have the same configuration as a conventionally known one, and a description of these configurations and operations will be omitted.

Next, the structure of the hold valve 4 will be described with reference to FIG. 2. The hold valve has a housing 4c having an inflow port 4a and an outflow port 4b.
In the housing 4c, a valve element 4d for opening and closing the inflow port 4a is slidably disposed in a liquid-tight state. A vibration sensor (piezoelectric element in this example) 11 for detecting the vibration of the valve element 4d is disposed on the housing 4c opposite to the inflow port 4a so as to face the valve element 4d, and the valve element 4d is always in the housing 4c. It is urged by the stored spring 4f so as to contact the piezoelectric element 11. A solenoid 4g is arranged around the housing 4c, and when a current flows through the solenoid 4g, the valve element 4d moves leftward in the drawing to close the inflow port 4a.
In the hold valve 4, when vibration occurs in the brake fluid pressure in the state of FIG. 2A in which the inflow port 4 a is open, the vibration causes the valve element 4 d to vibrate, and the vibration is detected by the piezoelectric element 11. Then, vibration can be detected as shown in (b). When the antilock control is started and a current flows through the solenoid, the valve element 4d moves to the left in the figure against the urging force of the spring 4f to close the inflow port 4a as shown in FIG. , The valve element 4d and the piezoelectric element 11 are separated from each other. In this state, the piezoelectric element 1
No. 1 does not detect the vibration of the valve element 4d as shown in (b).

As shown in FIG. 1, the hydraulic pressure oscillating device 7 includes a cylindrical main body 7a, a piston 7b slidably provided in the main body 7a in a liquid-tight manner, and a piezoelectric element for applying vibration to the piston 7b. 7c, and a hydraulic chamber 7e partitioned by a piston 7b and communicating with the wheel cylinder 6. The frequency of the brake fluid pressure fluctuation currently occurring in the brake fluid pressure is determined by a specific value of the vehicle body and the steering. When the relationship becomes, the piston 7b is operated by the piezoelectric element 7c by a signal from the electronic control unit 13,
The brake fluid pressure is forcibly excited at values other than the characteristic values of the vehicle body and the steering to suppress occurrence of abnormal vibration. The vibration hydraulic pressure generation mechanism is not limited to the piezoelectric element,
Of course, other vibration mechanisms can be used.

The reservoir 8 has a function of allowing the brake fluid from the wheel cylinder 6 to flow when the decay valve 5 is opened. When the pump 9 operates, the brake fluid in the reservoir 8 is transferred to the master cylinder. Pumped up. A piston 8b urged upward in the figure by a spring 8a is slidably disposed in a liquid-tight manner in a cylinder constituting the reservoir 8, and a liquid chamber 8c is defined in the cylinder by the piston 8b. ing. The liquid chamber 8c is connected to the pump 9 and the decay valve 5. The piston 8b is provided with a stroke sensor 12 for detecting the stroke of the piston 8b. When the stroke sensor 12 detects that the stroke of the piston 8b has become maximum, the pump 9 is operated by a signal from the electronic control unit 13 to pump the brake fluid in the fluid chamber 8c to the master cylinder. The pump 9 also operates during the anti-lock control, and has the function of pumping up the brake fluid in the reservoir.

The operation of the brake fluid pressure control device having the above configuration will be described. In this brake fluid pressure control device, when the brake pedal 1 is depressed, the fluid pressure generated in the master cylinder 3 flows into the wheel cylinder 6 via the open hold valve 4 to operate the brake. When the brake pedal 1 is released, the brake fluid in the wheel cylinder 6 returns to the master cylinder via the hold valve 4, and the brake is released. Further, when the wheels tend to lock during the operation of the brake, the hold valve 4 and the decay valve 5 are opened and closed by a known method to execute anti-lock control such as reduction, holding, and re-pressurization of the brake fluid pressure. When the antilock control is started, the valve element 4d in the hold valve 4 is separated from the vibration sensor 11 as shown in FIG. It is possible to prevent interference with control for suppressing judder and creep grown, which will be described later.

Further, judder generated during the operation of the brake is suppressed as follows. That is, the brake fluid pressure vibration generated during the braking operation is detected by the vibration sensor 11, and the wheel speed is detected by the wheel speed sensor 10 and output to the electronic control unit 13. The electronic control unit 13 operates the piezoelectric element 7c and oscillates the piston 7b according to a control flow described later when judder occurs to cause a frequency of the currently occurring brake fluid pressure fluctuation and a characteristic value of the vehicle body and the steering. The piezoelectric element 7 is controlled by a signal from the electronic control unit 13 so that the predetermined relationship is not established.
The piston 7b is actuated by c to actively suppress the vibration generated in the brake fluid pressure.

[0014] Further, the creep groon generated during the creep running is suppressed as follows. That is, when the brake pedal is operated and the speed detected by the wheel speed sensor 10 becomes equal to or lower than a predetermined speed and the vibration level detected by the vibration sensor 11 becomes equal to or higher than a predetermined value, the hold valve 4 is closed and the decay valve 5 is simultaneously opened. It opens to rapidly reduce the pressure of the brake fluid in the wheel cylinder 6. Further, when the vibration level detected by the vibration sensor 11 becomes equal to or less than a predetermined value, the hold valve 4 is opened and at the same time the decay valve 5 is opened.
To close to the normal braking state. By this action,
Even if the pedal force is slightly loosened while the vehicle is stopped and held in the traveling range (creep running) of the automatic transmission, the generation of creep grown (so-called goo noise) is prevented. The depressurized brake fluid amount is absorbed by the reservoir 8, but when the brake fluid amount exceeds a certain amount, the pump operation signal is input to the electronic control unit 13 by a signal from the stroke sensor 12 and returned to the master cylinder by the pump 9. .

An example of a control flow for preventing judder will be described with reference to FIGS. The program of (a) is started, and it is determined in step S1 whether or not the hydraulic vibration level detected from the vibration sensor 11 is equal to or higher than a reference value.
In step 2, the wheel speed at that time is detected, and the wheel speed and 1/2 of the wheel speed are calculated. Then, the frequency of torque fluctuation corresponding to those wheel speeds is estimated by the following equation. ft = V / (3.6 × π × D) (1) where ft: brake torque fluctuation frequency (Hz) V: vehicle speed (km / h) D: tire diameter (m) The frequency of the fluid pressure fluctuation is obtained by the following equation. fp = V / (3.6 × π × D) (2) where fp: brake fluid pressure fluctuation frequency (Hz) V: vehicle speed (km / h) D: tire diameter (m) and the obtained brake torque fluctuation The wheel speed at which the frequency ft and the brake fluid pressure fluctuation frequency fp coincide with the vehicle body and steering characteristic values or あ る い は thereof is obtained, and then the process proceeds to step S3, where the wheel speed obtained at step S2 is stored. Keep it.

When the program (b) is started, it is determined in step SS1 whether or not the brake switch is ON. The brake switch may be any type as long as it can detect whether the brake operating member is operated or not. When the brake operating member is operated (that is, the brake is operated), the switch is turned on. Become. If the switch is ON, the process proceeds to step SS2, where it is determined whether the hydraulic vibration level is equal to or higher than the reference value. If the hydraulic vibration level detected from the vibration sensor 11 is equal to or higher than the reference value, the process proceeds to step SS3 and the above-described ( The wheel speed (that is, the brake fluid pressure fluctuation frequency fp) stored in step S3 of the flowchart in FIG.
The actual wheel speeds are compared with the actual wheel speeds, and when they match, the process proceeds to step SS4, where the hold valve 4 is closed, and at the same time, the hydraulic pressure oscillation device 7 is turned to the steering system eigenvalue (resonance). By vibrating at a frequency greater than (frequency) f _R , the brake fluid pressure is forcibly vibrated. In this way, the vibration of the brake fluid pressure and the natural value (resonance frequency) f _{R of the} vehicle body and the steering system do not coincide or become equal to 、, and the occurrence of judder can be reliably suppressed.

Next, a control flowchart for preventing the occurrence of creep grown will be described with reference to FIG. In FIG. 5, when the creep-glow occurrence prevention control is started, in step S1, the vehicle speed is fetched from the wheel speed sensor 10, and it is determined whether or not this vehicle speed is equal to or lower than a reference speed (for example, V = 5 km / h or lower). When the speed is equal to or lower than the reference speed, the process proceeds to step S2, in which the output from the vibration sensor 11 is fetched to determine whether or not the vibration level at that time is equal to or higher than the reference.

When the vibration level from the vibration sensor 11 is equal to or higher than the reference, it is determined that a creep loss has occurred, and the flow advances to step S3 to close the hold valve 4, open the decay valve 5, and discharge the brake fluid in the wheel cylinder 6. It returns to the reservoir 8 to reduce the brake fluid pressure. Next, in step S4, when the vibration level from the vibration sensor 11 falls below the reference, it is determined that the creep grown has disappeared,
Open the hold valve 4, close the decay valve 5,
Return to normal braking. In this way, the state in which the balance between the driving torque and the braking torque is barely reduced by loosening the pedaling force, that is, by avoiding the hydraulic pressure at which the creep grone is generated, the generation of the creep grone can be prevented.

The state in which the hysteresis of the brake booster is changed will be described with reference to FIG. 6. When the reference speed of the vehicle is equal to or lower than a predetermined speed, the brake fluid pressure becomes P1.
When it decreases to below, a creep groon occurs and the vibration level exceeds the standard. Therefore, in this state, the hold valve and the decay valve are switched to reduce the brake fluid pressure. After that, the creep groon disappears and when the vibration level falls below the standard, the hold valve 4 and the decay valve 5
Is returned to the normal brake operation state. FIG. 6 shows the hysteresis for preventing the occurrence of the creep grown (that is, the brake booster during the creep-glow occurrence prevention control has the hysteresis indicated by a, b, c, d, e, f, and g in the figure). . As described above, in the above embodiment, the occurrence of creep can be suppressed in a wide range, and when the driver stops and holds the vehicle in the traveling range (creep traveling) of the automatic transmission, the pedal force is unknowingly unknowingly. Even if it is loosened, it is possible to reliably prevent the occurrence of creep grown. Although the solenoid valve according to the above embodiment has been described as an example in which the solenoid valve is used as a brake noise for detecting hydraulic vibration in the brake circuit and a hydraulic pressure sensor for abnormal vibration control, the hydraulic pressure according to the present invention is described. The electromagnetic valve having the vibration detection sensor function is not limited to the brake circuit, but can be applied to various hydraulic circuits to detect the hydraulic vibration in the hydraulic circuit.

[0020]

As described in detail above, according to the present invention,
By installing a vibration sensor on the anti-lock control hold valve that is standard equipment in recent vehicles, it is necessary to provide a vibration sensor for each wheel to detect the vibration used to prevent the occurrence of judder and creep gron And the system can be greatly simplified.
When the frequency of the brake fluid pressure fluctuation has a predetermined relationship with the vehicle body and the steering characteristic value by using the above-described vibration sensor, the brake fluid pressure is forcibly excited by the oscillation device at a value other than the vehicle body and the steering characteristic value. Thereby, the resonance phenomenon can be avoided, and abnormal vibration such as judder can be reliably suppressed. Further, the vibration of the brake fluid pressure is detected during creep running, and when the vibration level is equal to or more than a predetermined value, it is determined that a creep grown (so-called goo noise) is occurring, and the brake fluid pressure is reduced to thereby provide a creep grone (so-called goo noise). Goo noise) can be eliminated, and excellent effects such as generation of creep grown can be reliably prevented.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram according to an embodiment of the present brake fluid pressure control device.

FIG. 2 is a sectional view of a solenoid valve incorporating a vibration sensor in a non-operating state and a detected vibration waveform diagram.

3A and 3B are a sectional view of an electromagnetic valve incorporating a vibration sensor in an operating state and a detected vibration waveform.

FIGS. 4A and 4B are control flowcharts for preventing judder.

FIG. 5 is a flow chart for preventing creep grown.

FIG. 6 is a hysteresis diagram showing how the creep grone disappears according to FIG. 5;

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 brake pedal 2 vacuum booster 3 master cylinder 4 solenoid valve (hold valve) 5 decay valve 6 wheel cylinder 7 hydraulic oscillating device 8 reservoir 9 pump 10 wheel speed sensor 11 vibration sensor 12 stroke sensor 13 electronic control unit (ECU)

Continued on the front page F term (reference) 3D046 BB07 CC02 HH00 LL14 LL15 LL23 3H002 BB08 BD01 BE02 3H082 AA24 BB01 CC02 DB26 DD01 DD12 DE05 EE14 3H106 DA07 DA23 DB02 DB12 DB23 DB32 DC02 DD02 EE20 HH10 KK22

Claims (1)

[Claims] An electromagnetic valve disposed in a fluid circuit and closing a flow passage by movement of a valve element receives liquid pressure in the flow path via the valve element when the flow path is open and converts it into an electric signal. An electromagnetic valve having a hydraulic vibration detection sensor function, comprising: a vibration detection element.