JP2006103547A - Hydraulic brake control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hydraulic brake control device capable of realizing a desired brake performance while effectively preventing heat generation of a normally open valve without the need for increasing the size of a normally open valve coil. .
The hydraulic brake control apparatus according to the present invention includes normally open valves 78 and 80, which are normally open and connected upstream to a wheel cylinder 16 and connected downstream to a low pressure source 18, as pressure reducing valves for the wheel cylinder. And the pressure difference reduction means 90 which reduces the pressure difference between the downstream of the said normally open valve and an upstream is characterized by the above-mentioned. The pressure difference reducing means may be a normally open solenoid valve provided in a pressure reducing passage 94 between the normally open valve and a low pressure source.
[Selection] Figure 1

Description

  The present invention relates to a hydraulic brake control device, and more particularly to a hydraulic brake control device having a normally open valve that is normally open as a pressure reducing valve for a wheel cylinder.

Conventionally, this kind of hydraulic brake control device is known (for example, refer to patent documents 1). Thus, when a normally open valve is used as the pressure reducing valve for the wheel cylinder, the wheel cylinder pressure can be released to the reservoir via the normally open valve when the system is abnormal, so that the fail-safe function is improved.
JP 2000-85567 A

  However, when a normally open valve is used as a pressure reducing valve for a wheel cylinder as in the above-described prior art, a holding current is required to keep the normally open valve closed when maintaining the desired wheel cylinder pressure. Since this holding current causes heat generation in the normally-open valve coil, it is necessary to provide an upper limit value for the wheel cylinder pressure that can be held in order to prevent failure of the normally-open valve due to the heat generation. For this reason, in the above-described configuration of the related art, if the upper limit value required from the viewpoint of improving the brake performance is increased, the normally open coil must be enlarged to prevent the normally open valve from generating heat while corresponding to this. Therefore, it has a disadvantageous aspect in terms of mounting space and cost.

  SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a hydraulic brake control device that can realize desired braking performance while effectively preventing heat generation of a normally open valve without requiring an increase in the size of a normally open coil.

In order to solve the above-described problem, according to one aspect of the present invention, a hydraulic pressure having a normally open valve whose upstream side is connected to a wheel cylinder and whose downstream side is connected to a low pressure source is open as a pressure reducing valve of the wheel cylinder. A brake control device,
There is provided a hydraulic brake control device comprising pressure difference reducing means for reducing a pressure difference between a downstream side and an upstream side of the normally open valve.

  In this aspect, the pressure difference reducing means may be a normally open solenoid valve provided between the normally open valve and the low pressure source. In the case of a hydraulic brake control device mounted on a vehicle having four wheels, a wheel cylinder related to a wheel that does not use the normally open valve as a pressure reducing valve has a normally closed valve that is normally closed as the pressure reducing valve. The downstream side of the normally closed valve may be connected to the low pressure source without the normally opened solenoid valve.

  According to the present invention, it is not necessary to enlarge the coil of the normally open valve, and a hydraulic brake control device that can achieve desired brake performance while effectively preventing heat generation of the normally open valve can be obtained.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  FIG. 1 is a system configuration diagram of a hydraulic brake control device according to an embodiment (first embodiment) of the present invention.

  The hydraulic brake control device of this embodiment is controlled by an electronic control unit (hereinafter referred to as ECU) 10. The ECU 10 is configured by a microcomputer and includes a CPU, a ROM, a RAM, an I / O, and the like.

  A stroke sensor 14 is disposed in the vicinity of the brake pedal 12 provided in the passenger compartment. The stroke sensor 14 outputs a signal corresponding to the pedal stroke amount of the brake pedal 12 to the ECU 10.

  A master cylinder 16 is connected to the brake pedal 12. The master cylinder 16 includes two hydraulic chambers 16a and 16b. A master cylinder pressure PM / C corresponding to the brake depression force is generated in the hydraulic chambers 16a and 16b. A reservoir tank 18 is disposed above the master cylinder 16. Brake fluid is stored in the reservoir tank 18. The hydraulic chambers 16a and 16b of the master cylinder 16 and the reservoir tank 18 are in a conductive state when the depression of the brake pedal 12 is released.

  A first master passage 20 and a second master passage 21 communicate with the hydraulic chambers 16a and 16b of the master cylinder 16, respectively. The first master passage 20 is provided with a master pressure sensor 22 for outputting a signal corresponding to the internal hydraulic pressure, that is, the master cylinder pressure PM / C generated in the hydraulic pressure chamber 16a. Similarly, the second master passage 21 is provided with a master pressure sensor 24 for outputting a signal corresponding to the internal fluid pressure, that is, the master cylinder pressure PM / C generated in the fluid pressure chamber 16b. Output signals from the master pressure sensors 22 and 24 are supplied to the ECU 10.

  The ECU 10 is supplied with a signal indicating the pedal stroke from the stroke sensor 14, and is also supplied with signals indicating the master cylinder pressure PM / C from the master pressure sensors 22 and 24.

  The first master passage 20 is connected to the left front wheel cylinder passage 28 via a master cut valve 26. The master cut valve 26 is a normally open electromagnetic on-off valve that normally connects the first master passage 20 and the left front wheel cylinder passage 28, and is supplied with an ON signal from the ECU 10, thereby shutting off these passages. It is. The left front wheel cylinder passage 28 communicates with the wheel cylinder 30 of the left front wheel FL. The left front wheel cylinder passage 28 is provided with a wheel cylinder pressure sensor 32 that outputs a signal corresponding to the internal hydraulic pressure, that is, the wheel cylinder pressure PW / C of the left front wheel.

  Similarly, the second master passage 21 is connected to the right front wheel cylinder passage 36 via the master cut valve 34. The master cut valve 34 is a normally open electromagnetic on-off valve that normally brings the second master passage 21 and the right front wheel cylinder passage 36 into a conducting state and is supplied with an ON signal from the ECU 10 to shut off these passages. It is. The right front wheel cylinder passage 36 communicates with the wheel cylinder 38 of the right front wheel FR. The right front wheel cylinder passage 36 is provided with a wheel cylinder pressure sensor 40 that outputs a signal corresponding to the internal hydraulic pressure, that is, the wheel cylinder pressure PW / C of the right front wheel FR.

  A stroke simulator 44 is also connected to the second master passage 21 via a simulator cut valve 42. The simulator cut valve 42 is a normally closed electromagnetic on-off valve that normally shuts off the second master passage 21 and the stroke simulator 44 and supplies them with an ON signal from the ECU 10. The stroke simulator 44 causes the brake fluid of an amount corresponding to the master cylinder pressure PM / C generated in the hydraulic pressure chamber 16b of the master cylinder 16 to flow into the interior of the master cylinder 16 under the condition that the simulator cut valve 42 is opened. It is configured.

  As long as no abnormality is detected in the system, the ECU 10 turns on the first master cut valve 26 and the second master cut valve 34 when the brake operation is performed. Under such circumstances, by turning the simulator cut valve 42 on (opened), an amount of brake fluid corresponding to the master cylinder pressure PM / C flows into the stroke simulator 44 from the hydraulic chamber 16b. Accordingly, a pedal stroke corresponding to the brake depression force is generated in a state where the first master cut valve 26 and the second master cut valve 34 are closed.

  A reservoir passage 45 communicates with the reservoir tank 18. The reservoir passage 45 communicates with the suction side of the pump device 46. The pump device 46 includes a pump 47 driven by a pump motor 47 a and an accumulator 48 that stores high-pressure brake fluid discharged from the pump 47. In addition, a relief valve 49 is provided, and the relief valve 49 functions to release excessive fluid pressure in the high-pressure passage 50 to the reservoir tank 18 via the reservoir passage 45.

  The discharge side of the pump device 46 communicates with the high pressure passage 50. The high pressure passage 50 is provided with a pump pressure sensor 52 that outputs a signal corresponding to the internal fluid pressure, that is, the pump pressure Pacc. The ECU 10 detects the pump pressure Pacc based on the output signal of the pump pressure sensor 52.

  The high pressure passage 50 is connected to the left front wheel cylinder passage 28 and the right front wheel cylinder passage 36 through a linear pressure increasing valve 54 and a linear pressure increasing valve 56, respectively. Further, the high pressure passage 50 is connected to the left rear wheel cylinder passage 62 and the right rear wheel cylinder passage 64 via the linear pressure increasing valve 58 and the linear pressure increasing valve 60, respectively. The left rear wheel cylinder passage 62 and the right rear wheel cylinder passage 64 communicate with the wheel cylinders 66 and 68 of the left rear wheel RL and the right rear wheel RR, respectively. The above-described linear pressure increasing valves 54 to 60 are all linear control valves that are normally closed and increase the opening according to the magnitude of the drive signal when a drive signal is supplied from the ECU 10. . Therefore, based on the drive current supplied to the linear pressure increasing valves 54-60, the left front wheel cylinder passage 28, the right front wheel cylinder passage 36, the left rear wheel cylinder passage 62, and the right rear wheel cylinder passage from the high pressure passage 50 side, respectively. The amount of brake fluid flowing into the 64 side can be controlled linearly.

  The left rear wheel cylinder passage 62 and the right rear wheel cylinder passage 64 are provided with wheel cylinder pressure sensors 70 and 72 for outputting signals corresponding to the wheel cylinder pressure PW / C of the left rear wheel RL and the right rear wheel RR, respectively. It is installed. The output signals of the wheel cylinder pressure sensors 32, 40, 70, 72 are all supplied to the ECU 10. The ECU 10 detects the wheel cylinder pressure PW / C of each wheel based on these output signals.

  The left front wheel cylinder passage 28, the right front wheel cylinder passage 36, the left rear wheel cylinder passage 62, and the right rear wheel cylinder passage 64 are respectively a linear pressure reducing valve 74, a linear pressure reducing valve 76, a linear pressure reducing valve 78, and a linear pressure reducing valve 80. Is connected to the decompression passage 94. A fluid pressure sensor 92 that outputs a signal corresponding to the fluid pressure inside the decompression passage 94 is disposed. The ECU 10 detects the hydraulic pressure in the decompression passage 94 based on the output signal of the hydraulic pressure sensor 92.

  The decompression passage 94 is connected to the reservoir passage 45 via the decompression cut valve 90. The decompression cut valve 90 is a normally-open electromagnetic on-off valve that normally places the decompression passage 94 and the reservoir passage 45 in a conducting state and is supplied with an ON signal from the ECU 10 to shut off these passages.

  When the linear pressure reducing valves 74 and 76 on the front wheel side are normally closed and the linear pressure reducing valves 78 and 80 on the rear wheel side are normally opened and a drive signal is supplied from the ECU 10, the magnitude of the drive signal is increased. It is a linear control valve that changes the opening according to the height. Therefore, based on the drive current supplied to the linear pressure reducing valves 74 to 80, the left front wheel cylinder passage 28, the right front wheel cylinder passage 36, the left rear wheel cylinder passage 62, and the right rear wheel cylinder passage 64 from the side of the reservoir passage, respectively. The amount of brake fluid flowing out to the 45 side can be controlled linearly.

  For example, the ECU 10 may generate a braking force from a request such as behavior control of the vehicle although (1) the brake pedal 12 is depressed and (2) the depression of the brake pedal 12 is released. When required, increase wheel cylinder pressure PW / C for each wheel. Hereinafter, the control executed in the case of (1) is called normal brake control, and the control executed in the case of (2) is called automatic brake control.

  In the hydraulic brake control device, when neither normal brake control nor automatic brake control is executed, the pump device 46 is stopped, and the master cut valves 26 and 34 are both turned off (opened). In addition, all the linear pressure increasing valves 54 to 60 and the linear pressure reducing valves 74 and 76 are closed, and the linear pressure reducing valves 78 and 80 are opened. In this case, the wheel cylinders 30, 38, 66 and 68 are disconnected from the high-pressure passage 50, and the state where the wheel cylinders 30 and 38 on the front wheel side communicate with the master cylinder 16 is formed. Hereinafter, this state is referred to as a static pressure supply state. In the hydraulic brake control of the present embodiment, the static pressure supply state is realized even when the ignition switch is turned off.

  Further, when an abnormality occurs in the system (for example, when abnormality occurs in the pump 47, the linear pressure increasing valves 54 to 60, or the linear pressure reducing valves 74 to 80, etc.), the linear pressure increasing valves 54 to 60 and the linear pressure reducing valve 74 are used. By controlling ˜80, the wheel cylinder pressure PW / C of each wheel cannot be properly controlled. The ECU 10 realizes a static pressure supply state even when these abnormalities are detected. As described above, the wheel cylinders 30 and 38 communicate with the master cylinder 16 in the static pressure supply state. Therefore, according to the hydraulic brake control device of the present embodiment, even when a system abnormality occurs, the wheel cylinder pressure PW / C equal to the master cylinder pressure PM / C is applied to the wheel cylinders 30 and 38 on the front wheel side. Can be generated. As described above, the hydraulic brake control device according to the present embodiment has an excellent fail-safe capability against system abnormality.

  On the other hand, at the time of normal brake control or automatic brake control, the pump device 46 is in an operating state, the master cut valves 26 and 34 are both turned on (closed), and the linear pressure-increasing valves 54 to 60 and the linear pressure-reducing valve. The valves 74 to 80 are controlled so that the required wheel cylinder pressure PW / C is generated in each wheel. Hereinafter, this state is referred to as a dynamic pressure supply state. In the dynamic pressure supply state, the wheel cylinders 30, 38, 66, and 68 generate wheel cylinder pressures PW / C corresponding to the opening degrees of the linear pressure increasing valves 54 to 60 and the linear pressure reducing valves 74 to 80, respectively. .

  Thus, in the dynamic pressure supply state, the wheel cylinder pressure PW / C of each wheel can be controlled to an arbitrary hydraulic pressure by adjusting the opening degree of the linear pressure increasing valves 54-60 and the linear pressure reducing valves 74-80. it can. Therefore, according to the hydraulic brake control apparatus of the present embodiment, the normal brake control can be realized by generating the wheel cylinder pressure PW / C corresponding to the brake operation amount. In addition, when a tendency of wheel lock occurs during normal brake control, the wheel cylinder pressure PW / C of each wheel is increased / decreased so that the slip ratio of the wheel does not exceed a predetermined value. ) Function can be realized. Furthermore, the wheel cylinder pressure PW / C of each wheel is appropriately controlled according to the demands of automatic brake control, thereby realizing traction control (TRC) function, vehicle attitude control (VSC), and other known automatic brake control. can do.

  By the way, in the present embodiment, as described above, the rear wheel side linear pressure reducing valves 78 and 80 are constituted by normally open valves (normally open valves). This is a configuration necessary for releasing the wheel cylinder pressure PW / C, which can be high when the system is abnormal, to the reservoir tank 18 via the reservoir passage 45. Therefore, in such a configuration, it is necessary to apply a current continuously to the linear pressure reducing valves 78 and 80 during braking and to close the linear pressure reducing valves 78 and 80.

  FIG. 2 is a graph showing the relationship between the differential pressure of the normally open valve and the holding current. As shown in FIG. 2, the current to be supplied to the linear pressure reducing valves 78 and 80 depends on the differential pressure before and after that, and the smaller the differential pressure, the smaller the current for holding the differential pressure.

  In this embodiment, the difference between the hydraulic pressure on the downstream side of the linear pressure reducing valve 78, that is, the hydraulic pressure in the pressure reducing passage 94, and the hydraulic pressure on the upstream side of the linear pressure reducing valve 78, that is, the hydraulic pressure in the left rear wheel cylinder passage 62 is different. The smaller the current, the smaller the current to be applied to the linear pressure reducing valve 78 in order to maintain the differential pressure. Similarly, the smaller the difference between the hydraulic pressure on the downstream side of the linear pressure reducing valve 80, that is, the hydraulic pressure in the pressure reducing passage 94, and the hydraulic pressure on the upstream side of the linear pressure reducing valve 80, that is, the hydraulic pressure in the right rear wheel cylinder passage 64. In order to maintain the differential pressure, the current to be applied to the linear pressure reducing valve 80 may be small.

  Here, in the present embodiment, as described above, since the pressure reducing passage 94 is connected to the reservoir passage 45 via the pressure reducing cut valve 90, the pressure reducing passage 94 is larger than zero by closing the pressure reducing cut valve 90. A hydraulic pressure can be generated. For example, the hydraulic pressure in the pressure reducing passage 94 can be increased by closing the pressure reducing cut valve 90 and introducing the accumulator pressure from the linear pressure increasing valve 54 (and / or the linear pressure increasing valve 56) on the front wheel side. Further, at this time, the hydraulic pressure in the pressure reducing passage 94 is desired by controlling the linear pressure increasing valve 54 (and / or the linear pressure increasing valve 56) and the pressure reducing cut valve 90 on the front wheel side based on the output signal of the hydraulic pressure sensor 92. It is also possible to change to the value of.

  Therefore, according to the present embodiment, it is the same as the conventional configuration in which the downstream side of the linear pressure reducing valves 78 and 80 directly communicates with the reservoir passage 45 (that is, the configuration in which the downstream side is 0 [MPa]). The wheel cylinder pressure PW / C can be maintained at a smaller current. In other words, when the pressure on the downstream side of the linear pressure reducing valves 78 and 80 is higher than zero by X [MPa], the wheel cylinder pressure PW / is higher by X [MPa] at the same current than the conventional configuration. C can be held.

  As described above, according to this embodiment, it is possible to maintain a high wheel cylinder pressure PW / C with a small current compared to the above-described conventional configuration, and it is possible to improve vehicle performance and save power. .

  Moreover, since the differential pressure between the upstream side and the downstream side of the linear pressure reducing valves 78 and 80 can be arbitrarily adjusted and maintained as described above, the linear pressure reducing valves 78 and 80 generate heat due to continuous energization. It can prevent adverse effects (such as melting of enameled wire due to heat generation in the coil section). For this reason, in order to increase the upper limit of the wheel cylinder pressure PW / C that can be maintained by continuous energization, the coil is undesirably enlarged from the viewpoint of the mounting space, and the heat radiation performance of the linear pressure reducing valves 78 and 80 is increased. No countermeasure is required.

  Therefore, according to the hydraulic brake control device of the present embodiment, in contrast to the conventional configuration in which the downstream side of the linear pressure reducing valves 78, 80 communicates directly with the reservoir passage 45, the wheel brake pressure can be maintained. The upper limit value can be increased or eliminated, and the durability of the linear pressure reducing valves 78 and 80 can be improved as well as the braking performance. Increasing the upper limit of the wheel cylinder pressure is advantageous for a vehicle having a particularly large mass that requires a large braking force when stopping on a slope.

  FIG. 3 is a flowchart showing a hydraulic pressure control method by the hydraulic brake control device of the present embodiment.

  In step 100, in the wheel cylinder normal hydraulic pressure control state in the dynamic pressure supply state described above, the ECU 10 determines the required braking force intended by the driver based on the signals from the stroke sensor 14 and the master pressure sensors 22 and 24. A target wheel cylinder pressure corresponding to the required braking force is determined for each wheel. Then, the ECU 10 detects that the wheel cylinder pressure PW / C detected by the wheel cylinder pressure sensors 32, 40, 70, 72 is the corresponding target wheel cylinder pressure, and the linear pressure increasing valves 54-60, and The linear pressure reducing valves 74 to 80 are controlled. In this wheel cylinder normal hydraulic pressure control state, no current is supplied to the decompression cut valve 90, and therefore the decompression cut valve 90 remains open.

  As step 110, the ECU 10 constantly monitors whether or not the target wheel cylinder pressure exceeds a predetermined threshold A when the vehicle is stopped in such a wheel cylinder normal hydraulic pressure control state. Here, the predetermined threshold A may be an upper limit value provided to prevent a failure due to heat generation due to continuous energization of the linear pressure reducing valves 78 and 80 as described above (see FIG. 2). That is, when a current is continuously applied to the linear pressure reducing valves 78 and 80, the coil portions of the linear pressure reducing valves 78 and 80 generate heat, so that the linear pressure reducing valve 78 is not heated beyond the allowable temperature. , 80 must be limited to the current value that can be energized continuously. The predetermined threshold A is set for such restriction.

  As long as the target wheel cylinder pressure does not exceed the predetermined threshold A in step 110, the ECU 10 determines that the heat generation prevention processing of the linear pressure reducing valves 78, 80 is unnecessary, and maintains the wheel cylinder normal hydraulic pressure control state. to continue.

  On the other hand, when the target foil cylinder pressure exceeds the predetermined threshold A in step 110, processing for preventing the heat generation of the linear pressure reducing valves 78 and 80 while realizing the target foil cylinder pressure is started (steps 120 and 130).

  In the present embodiment, the current applied to the linear pressure reducing valves 78 and 80 is limited particularly in the processing of step 120, but it is characteristic that the target wheel cylinder pressure exceeding the threshold A can be realized while adding such limitation. is there.

  Specifically, as step 120, while maintaining the current applied to the linear pressure reducing valves 78 and 80, the pressure reducing cut valve 90 is closed and the pressure reducing passage 94 is increased in pressure. The pressure increase in the pressure reducing passage 94 may be realized, for example, by introducing the accumulator pressure from the front wheel side linear pressure increasing valve 54 (and / or the linear pressure increasing valve 56).

  At this time, the ECU 10 compensates the hydraulic pressure in the pressure reducing passage 94 by an amount exceeding the hydraulic pressure that can be held by the linear pressure reducing valves 78 and 80. That is, the ECU 10 sets the linear pressure increasing valves 54 and 56 and the linear pressure reducing valves 74 and 76 so that the hydraulic pressure in the pressure reducing passage 94 detected by the hydraulic pressure sensor 92 becomes a target value (= target wheel cylinder pressure−threshold A). In addition, the decompression cut valve 90 is appropriately controlled.

  At the same time, as step 130, the ECU 10 increases linearly so that the wheel cylinder pressure PW / C of each wheel detected by the wheel cylinder pressure sensors 32, 40, 70, 72 becomes the corresponding target wheel cylinder pressure. The pressure valves 54 to 60 and the linear pressure reducing valves 74 to 80 are controlled.

  The processing of steps 120 and 130 is continuously executed until the target wheel cylinder pressure falls below a predetermined threshold A (step 140), for example, when the driver releases the brake pedal.

  As described above, according to this embodiment, it is not necessary to apply a high current exceeding the allowable limit to the linear pressure reducing valves 78 and 80 in order to realize a desired wheel cylinder pressure. The durability of the pressure reducing valves 78 and 80 can be improved.

  In this embodiment, in step 120, the current applied to the linear pressure reducing valve 78 and the linear pressure reducing valve 80 may be reduced. In this case, the pressure reducing passage 94 is increased so as to further compensate for the decrease, and a differential pressure is achieved so that the linear pressure reducing valve 78 and the linear pressure reducing valve 80 can maintain the target wheel cylinder pressure with the reduced holding current. To do.

  Similarly, in step 120, the current supplied to the linear pressure reducing valve 78 and the linear pressure reducing valve 80 may be zero. In this case, the pressure in the pressure reducing passage 94 is increased so that the hydraulic pressure in the pressure reducing passage 94 becomes the target wheel cylinder pressure. In this case, the target wheel cylinder pressure can be realized without energizing the linear pressure reducing valve 78 and the linear pressure reducing valve 80.

  Further, in step 110 described above, even in the wheel cylinder normal hydraulic pressure control state (that is, even when the target wheel cylinder pressure is lower than the predetermined threshold A), the pressure reducing cut valve 90 is closed and the predetermined pressure in the pressure reducing passage 94 is set. Pressure (non-zero fluid pressure) may be maintained. In this case, since the holding current for maintaining the same wheel cylinder pressure may be smaller than that when the hydraulic pressure in the pressure reducing passage 94 is zero, power saving can be achieved without impairing necessary brake performance. be able to.

  Next, a second embodiment of the hydraulic brake control device according to the present invention will be described with reference to FIG. The same components as those in the above-described embodiment are designated by the same reference numerals, and description thereof is omitted.

  This embodiment differs from the first embodiment described above in that the pressure reducing cut valve 90 (and the pressure reducing passage 94) is set only for the linear pressure reducing valves 78, 80 on the rear wheel side. That is, the left rear wheel cylinder passage 62 and the right rear wheel cylinder passage 64 are connected to the pressure reducing passage 94 via the linear pressure reducing valves 78 and 80, respectively, and thus communicate with the reservoir passage 45 via the pressure reducing cut valve 90. become. On the other hand, the left front wheel cylinder passage 28 and the right front wheel cylinder passage 36 communicate with the reservoir passage 45 without passing through the pressure reducing cut valve 90.

  According to this embodiment, since the pressure reducing cut valve 90 does not exist between the left front wheel cylinder passage 28 and the right front wheel cylinder passage 36 and the reservoir passage 45, the front series (front wheel side series) is the orifice of the pressure reducing cut valve 90. It is possible to prevent the performance degradation of the front-line decompression characteristics without being affected by the pressure loss due to.

  In this embodiment, as in the first embodiment, the pressure reducing cut valve 90 is closed, and the accumulator pressure is increased from the rear wheel side linear pressure increasing valve 58 (and / or the linear pressure increasing valve 60) via the high pressure passage 50. By introducing (in this introduction, the linear pressure reducing valve 78 and / or the linear pressure reducing valve 80 is temporarily opened), the hydraulic pressure in the pressure reducing passage 94 can be increased. Further, at this time, the hydraulic pressure in the pressure reducing passage 94 is controlled by controlling the linear pressure increasing valve 58 (and / or the linear pressure increasing valve 60) and the pressure reducing cut valve 90 on the rear wheel side based on the output signal of the hydraulic pressure sensor 92. It is also possible to change to a desired value.

  Therefore, according to the present embodiment, it is the same as the conventional configuration in which the downstream side of the linear pressure reducing valves 78 and 80 directly communicates with the reservoir passage 45 (that is, the configuration in which the downstream side is 0 [MPa]). The wheel cylinder pressure PW / C can be maintained at a smaller current. In other words, when the pressure on the downstream side of the linear pressure reducing valves 78 and 80 is higher than zero by X [MPa], the wheel cylinder pressure PW / is higher by X [MPa] at the same current than the conventional configuration. C can be held.

  As described above, according to this embodiment, it is possible to maintain a high wheel cylinder pressure PW / C with a small current compared to the above-described conventional configuration, and it is possible to improve vehicle performance and save power. .

  Further, since the differential pressure between the upstream side and the downstream side of the linear pressure reducing valves 78 and 80 can be arbitrarily adjusted as described above, adverse effects due to heat generated by the linear pressure reducing valves 78 and 80 due to continuous energization of the linear pressure reducing valves 78 and 80 ( The melting of the enamel wire due to the heat generated in the coil portion can be prevented. For this reason, in order to increase the upper limit of the wheel cylinder pressure PW / C that can be maintained by continuous energization, the coil is undesirably enlarged from the viewpoint of the mounting space, and the heat radiation performance of the linear pressure reducing valves 78 and 80 is increased. No countermeasure is required.

  Therefore, according to the hydraulic brake control device of the present embodiment, in contrast to the conventional configuration in which the downstream side of the linear pressure reducing valves 78, 80 communicates directly with the reservoir passage 45, the wheel brake pressure can be maintained. The upper limit value can be increased or eliminated, and the durability of the linear pressure reducing valves 78 and 80 can be improved as well as the braking performance. Increasing the upper limit of the wheel cylinder pressure is advantageous for a vehicle having a particularly large mass that requires a large braking force when stopping on a slope.

  The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above-described embodiments, and various modifications and substitutions can be made to the above-described embodiments without departing from the scope of the present invention. Can be added.

  For example, in the second embodiment described above, the decompression cut valve 90 and the decompression passage 94 can be set only for one of the linear decompression valves 78 and 80.

  In the above-described embodiment, each valve does not necessarily have to be a linear valve, and may be realized by a duty-controlled on-off valve.

1 is a system configuration diagram of a hydraulic brake control device according to a first embodiment of the present invention. FIG. It is a graph which shows the relationship between the differential pressure | voltage of a normally open valve, and holding current. It is a flowchart which shows the hydraulic pressure control method by the hydraulic brake control apparatus of a present Example. It is a system block diagram of the hydraulic brake control apparatus by 2nd Example of this invention.

Explanation of symbols

16 Master cylinder 18 Reservoir tank 26, 34 Master cut valve 30, 38, 66, 68 Wheel cylinder 46 Pump device 54, 56, 58, 60 Linear pressure increasing valve 74, 76, 78, 80 Linear pressure reducing valve Pressure reducing cut valve 90
Hydraulic pressure sensor 92

Claims (3)

A hydraulic brake control device having a normally open valve that is connected to a wheel cylinder on the upstream side and connected to a low pressure source on the downstream side as a pressure reducing valve for the wheel cylinder,
A hydraulic brake control device comprising pressure difference reducing means for reducing a pressure difference between a downstream side and an upstream side of the normally open valve.   2. The hydraulic brake control device according to claim 1, wherein the pressure difference reducing means is a normally open electromagnetic valve provided between the normally open valve and a low pressure source. The hydraulic brake control device according to claim 2, which is mounted on a vehicle having four wheels.
The wheel cylinder related to the wheel which does not use the normally open valve as a pressure reducing valve has a normally closed normally closed valve as a pressure reducing valve, and the downstream side of the normally closed valve is not connected to the low pressure source via the normally open electromagnetic valve. The hydraulic brake control device according to claim 2, wherein the hydraulic brake control device is connected to the hydraulic brake.

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