JPH08104217A - Brake system - Google Patents

Abstract

PURPOSE: To quickly detect a brake operation so as to quickly finish traction control, in the case of performing the brake operation during executing the traction control of form such as actuating a brake with a pump serving as the pressure source. CONSTITUTION: During traction control, not by continuing the first solenoid valve 30 as a closed condition but by providing the timing of obtaining an opening condition, when stepped in a brake pedal 14 during the traction control, it is performed so as to discharge a brake fluid from a master cylinder 10 to a front wheel brake cylinder 22. Thus by increasing a step-in stroke of the brake pedal 14 during the traction control, a brake operation is quickly detected by a brake switch 260, and the traction control is quickly ended by a controller 300, so as to quickly restore the first solenoid valve 30 to the opening condition.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brake system for a vehicle, and more particularly to a brake system for executing traction control by operating a brake using a pump as a pressure source.

[0002]

2. Description of the Related Art Japanese Unexamined Patent Publication (Kokai) No. 5-116607 discloses a brake system which executes traction control by operating a brake using a pump as a pressure source. Specifically, this brake system includes (a) a master cylinder that generates hydraulic pressure by operating a brake operating member by a driver, and (b) a brake cylinder of a drive wheel connected to the master cylinder by a main passage,
(c) A normally open solenoid valve provided in the main passage, and (d)
A reservoir connected to the master cylinder by an auxiliary passage, wherein a reservoir piston is substantially airtightly and slidably fitted in the housing to form a reservoir chamber for containing a reservoir liquid in the housing. When the volume of the chamber increases from the normal value, the reservoir piston is displaced from the normal position to the volume increase position, and when the volume decreases from the normal value to the normal position to the volume decrease position, and (e) is provided in the auxiliary passage, In the seated state, the valve seat and valve seat prevent the inflow of brake fluid from the master cylinder to the reservoir. When the valve seat is seated on the valve and the valve is separated from the valve seat when the volume is reduced and hydraulic pressure is generated in the master cylinder, The valve is installed in the pump passage that connects the inflow control valve where the valve seats on the valve seat, (f) the reservoir, and the part of the main passage between the electromagnetic on-off valve and the brake cylinder, and pumps the brake fluid from the reservoir. A pump,
(g) Brake operation detecting means for detecting a brake operation by the driver, and (h) controlling the hydraulic pressure of the brake cylinder via the electromagnetic hydraulic pressure control device including the electromagnetic opening / closing valve while operating the pump when the vehicle is driven. Thus, the controller includes a controller that executes traction control for preventing the drive wheels from idling, and terminates the traction control when the brake operation detecting means detects the brake operation.

[0003]

Traction control is generally designed to be terminated by detecting the end of the idle tendency of the drive wheels. Here, the detection of the end of the idling tendency is performed based on, for example, detecting that the operation of the acceleration operation member such as the accelerator pedal has been released, or the traction control enables stable and stable slipping of the driving wheels with a small amount. It is performed based on detecting that the state has been changed to the existing state. However, if the end of the idling tendency cannot be detected for some reason or if it takes a long time to detect the end, the brake operation may be started before the traction control is completed. Traction control is also generally designed to end with the detection of the start of actuation of a brake actuation member, such as a brake pedal. Here, in order to detect the brake operation, a displacement amount of a certain amount or more of the brake operation member is generally required. Therefore, in order to detect the brake operation during the traction control, it is necessary to secure a constant displacement amount of the brake operation member during the traction control.

However, when the brake system described in the above publication is used, a constant displacement amount of the brake operating member is not always secured quickly during the traction control, and the brake operation is not performed during the traction control. The traction control may not end immediately even if it is started.
Hereinafter, a specific description will be given.

In the brake system described in that publication, the electromagnetic opening / closing valve is kept closed during the traction control to prevent the flow of the brake fluid in the direction from the master cylinder to the brake cylinder. Further, during the traction control, the valve element is separated from the valve seat in the inflow control valve, and the inflow of the brake fluid from the master cylinder into the reservoir is allowed. However, in a situation where the viscosity of the brake fluid is low and the brake fluid easily passes through the gap between the valve element and the valve seat, a sufficient flow rate of the brake fluid can be secured even in a narrow gap, so that the brake fluid in the reservoir chamber is The tendency of shortage is weak, the reservoir piston is not largely displaced to the volume reduction position side, and the valve element is not sufficiently separated from the valve seat. Therefore, if a brake operation is performed during traction control, the brake cylinder is discharged from the master cylinder through the inflow control valve to the reservoir between the time when the brake operation is started and the time when the valve seats on the valve seat due to hydraulic pressure generation in the master cylinder. There is a case where the amount of the brake fluid to be applied is small, the constant displacement amount of the brake operating member cannot be secured quickly, and the brake operation cannot be detected promptly. For these reasons, the brake system described in the publication has a problem that if the brake operation is performed during the traction control, the braking effectiveness may be delayed.

Therefore, the invention of claim 1 increases the displacement of the brake operating member during the traction control by allowing the flow of the brake fluid in the direction from the master cylinder to the brake cylinder at least once during the traction control. Has been made to solve the problem of delayed braking.

Further, the invention of claim 2 increases the amount of brake fluid that can be discharged from the master cylinder to the reservoir through the inflow control valve during traction control to increase the displacement amount of the brake operating member during traction control. Therefore, the problem was to solve the problem of delayed braking.

[0008]

In order to solve each of the problems, the invention of claim 1 provides the above-mentioned (a) master cylinder, (b) brake cylinder, (c) solenoid on-off valve, (d). In a brake system including a reservoir, (e) inflow control valve, (f) pump, (g) brake operation detection means, and (h) controller, the controller is an electromagnetic fluid including an electromagnetic on-off valve while operating the pump when the vehicle is driven. It is characterized in that the traction control is executed by controlling the pressure control device including the time when the electromagnetic on-off valve is opened.

Further, the invention of claim 2 is the above-mentioned (a) master cylinder, (b) brake cylinder, (c) electromagnetic on-off valve, (d) reservoir, (e) inflow control valve, (f) pump. ， (G)
In a traction type braking system that includes a brake operation detection means and (h) a controller, the brake in the direction from the master cylinder to the reservoir when the valve element is close to the valve seat in the position where the valve element is separated from the valve seat in the inflow control valve. It is characterized in that a flow path resistance control mechanism for increasing the flow path resistance of the liquid and decreasing it in the state at a distant position is provided.

Here, the "flow passage resistance control mechanism" may be, for example, a mode of controlling the flow passage resistance in the portion of the auxiliary passage between the inflow control valve and the reservoir, or the master passage of the auxiliary passage with the master cylinder. In a mode in which the flow path resistance in the portion between the control valve and the control valve is controlled, or in the portion between the master cylinder and the connection position of the auxiliary passage in the main passage when the auxiliary passage is connected in the middle of the main passage. When the flow path resistance is controlled or when a relief valve is provided in the middle of the auxiliary passage and the relief passage extending from the discharge port of the pump is connected, the connection position between the master cylinder and the relief passage in the auxiliary passage It is possible to adopt a mode in which the flow path resistance in the portion between the two is controlled.

[0011]

In the brake system according to the first aspect of the present invention, the controller controls the electromagnetic hydraulic pressure control device so as to include the time when the electromagnetic opening / closing valve of the controller is opened during the traction control. That is, when the electromagnetic on-off valve is kept closed during traction control, the flow of the brake fluid in the direction from the master cylinder to the brake cylinder is continuously blocked, but in the device of the present invention, during the traction control. There is a time when the electromagnetic opening / closing valve is opened, that is, a time when the flow of the brake fluid in the direction from the master cylinder to the brake cylinder is allowed. Therefore, in the device of the present invention,
Even during traction control, the discharge of brake fluid from the master cylinder to the brake cylinder is allowed, and as a result, the amount of displacement of the brake operating member increases, which facilitates quick detection of brake operation and reduces brake operation. The brake cylinder quickly increases its pressure without waiting for detection.

In the brake system according to the second aspect of the present invention, the flow path resistance control mechanism is directed from the master cylinder to the reservoir when the valve element is located near the valve seat out of the positions separated from the valve seat. The flow resistance of the brake fluid is increased, and it is reduced at a distant position.

Therefore, in the inflow control valve, the resistance of the brake fluid from the master cylinder to the reservoir increases as the valve position is closer to the valve seat. Therefore, even if the viscosity of the brake fluid is low, the brake fluid flows from the master cylinder to the reservoir. The tendency of insufficient supply of brake fluid has increased, and as a result,
The reservoir piston is further displaced from the normal position toward the volume reduction position, and the position of the valve element is further moved from the valve seat to reduce the flow path resistance. Further displacement of the reservoir piston from the normal position toward the volume reduction position means that the reservoir piston is displaced from the volume reduction position to the normal position side when the valve element that is separated from the valve seat is seated on the valve seat by the brake operation. It means that the amount of increase in the volume of the reservoir chamber increases, which means that when the braking operation is started with the valve element separated from the valve seat, the reservoir can absorb the master cylinder. Means that the amount of brake fluid is increased. Therefore, in the device of the present invention, if the brake operation is performed during traction control, the amount of brake fluid that the master cylinder can discharge into the reservoir chamber after the brake operation is started until the valve seat is seated on the valve seat. As a result, the amount of displacement of the brake operating member increases, which facilitates quick detection of brake operation.

[0014]

As is apparent from the above description, according to the invention of claim 1 or 2, the displacement amount of the brake operating member during the traction control is increased to facilitate the quick detection of the brake operation, and the brake operation is facilitated. Since it becomes easy to end the traction control immediately after the operation, it is possible to obtain an effect that a delay in braking effectiveness is avoided.

In particular, according to the first aspect of the invention, since the flow of the brake fluid in the direction from the master cylinder to the brake cylinder is secured at least once during the traction control, the brake operation should be detected. Is not possible or takes a long time to detect it, the master cylinder quickly increases the pressure of the brake cylinder,
It is possible to obtain the effect that the driver's intention is reliably and promptly reflected in the traveling state of the vehicle.

[0016]

Preferred Embodiments of the Invention Below, some preferred embodiments of the invention of each claim will be described. (1) The invention according to claim 1, wherein the left and right front wheels are provided on a four-wheel vehicle in which the driving wheels and the left and right rear wheels are non-driving wheels, and are independent from each other of the two pressurizing chambers of the master cylinder. The two brake systems extending diagonally are diagonally configured, and the rear wheel brake passage branches from the middle of the front wheel brake passage that connects each pressurizing chamber of the master cylinder and the front wheel brake cylinder for each brake system. It reaches the brake cylinder, and in the part between the master cylinder and the connection position of the rear wheel brake passage in the front wheel brake passage,
A first solenoid valve, which is a normally open solenoid on-off valve, is provided, a second solenoid valve, which is a normally open solenoid on-off valve, is provided in the rear wheel brake passage, and the reservoir piston and the reservoir are provided by an auxiliary passage in the master cylinder. A reservoir including a chamber is connected, and the pump is provided in a pump passage extending from the reservoir to reach a portion of the rear wheel brake passage between the connection position of the front wheel brake passage and the second electromagnetic valve, and the auxiliary passage is provided. , Has a valve element and valve seat that prevent the brake fluid from flowing from the master cylinder to the reservoir in the seated state, and when the hydraulic pressure does not occur in the master cylinder, the valve element opens when the reservoir piston is in the volume increasing position. When the valve is seated on the seat and the volume is reduced, the valve element separates from the valve seat, and when hydraulic pressure is generated in the master cylinder, the valve element is seated on the valve seat. The check valve is provided in a return passage extending from a portion of the rear wheel brake passage between the second solenoid valve and the rear wheel brake cylinder to reach the master cylinder, and a brake for detecting a brake operation by a driver is provided. The operation detecting means is provided, and the controller controls at least one of the first solenoid valve and the second solenoid valve at a timing when the first solenoid valve is in an open state while operating the pump when the vehicle is driven. A brake system that executes traction control to prevent the front wheels from idling, and terminates the traction control in response to the brake operation detecting means detecting a brake operation. Here, the "front wheel brake cylinder" corresponds to the "brake cylinder" in the invention of claim 1, the "first electromagnetic valve" corresponds to the "electromagnetic on-off valve" in the invention of claim 1, and The "first solenoid valve and the second solenoid valve" correspond to the "electromagnetic hydraulic pressure control device" in the first aspect of the invention. (2) In the invention of (1), the controller is a front wheel open-rear wheel closed state in which the first solenoid valve is in the open state and the second solenoid valve is in the closed state, and the first solenoid valve is in the closed state. (2) A brake system for performing solenoid valve control including duty control for increasing / decreasing the hydraulic pressure of the front wheel brake cylinder by alternately repeating a front wheel closed state and a rear wheel opened state in which the solenoid valve is opened. (3) The invention of claim 2, wherein the flow path resistance control mechanism is provided between a large diameter partial passage and a small diameter partial passage which are a part of the auxiliary passage and are adjacent to each other, and And a small-diameter portion which has a rod-shaped displacement member which is displaced by the reservoir piston, and the large-diameter portion of the displacement member has a small-diameter partial passage when the reservoir piston is in a position close to the normal position among the volume reduction positions. The large diameter portion of the displacement member moves into the large diameter portion passage to reduce the small diameter portion of the displacement member in a state in which the effective flow passage area is reduced and the volume reduction position is located away from the normal position. A brake system that is a stroke response type variable throttle mechanism that is located in a small diameter partial passage to increase the effective flow passage area.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention of each claim will be specifically described below based on the illustrated embodiments. In FIG. 1, reference numeral 10 indicates a master cylinder. The master cylinder 10 is a tandem type in which two independent pressurizing chambers are arranged in series.
The master cylinder 10 is linked to a brake pedal 14 as a brake operating member via a booster (not shown), and liquids of the same height are provided in the two pressurizing chambers according to the depression of the brake pedal 14 by the driver. Each pressure is mechanically generated.

In one pressurizing chamber of the master cylinder 10,
The left front wheel brake cylinder, which is a driving wheel, and the right rear wheel brake cylinder, which is a non-driving wheel, are respectively connected, and the other pressurizing chamber is a right front wheel brake cylinder, which is a driving wheel, and a non-driving wheel. The left rear wheel brake cylinder is connected to each. The two brake systems extending from each pressurizing chamber of the master cylinder 10 are diagonally configured independently of each other. The left and right front wheels are subject to both antilock control and traction control, and the left and right rear wheels are subject to antilock control only.
Hereinafter, only one brake system will be described in detail, and the other brake systems have the same configuration in common, and thus the description thereof will be omitted.

One pressurizing chamber of the master cylinder 10 is connected to a front wheel brake cylinder 22 by a front wheel brake passage 20. A rear wheel brake passage 24 is branched from the middle of the front wheel brake passage 20, and a rear wheel brake cylinder 26 is connected to the tip thereof.

A first solenoid valve 30 is provided in a portion of the front wheel brake passage 20 closer to the master cylinder 10 than the connecting position of the rear wheel brake passage 24. The first solenoid valve 30 is a normally open solenoid valve. Rear wheel brake passage 24
Is provided with a second solenoid valve 60 which is a normally open solenoid valve. Further, the second part of the rear wheel brake passage 24
A reservoir passage 62 is connected to a portion between the solenoid valve 60 and the rear wheel brake cylinder 26. Reservoir passage 6
Reference numeral 2 extends from the reservoir 70, and a third electromagnetic valve 72, which is a normally closed electromagnetic opening / closing valve, is provided in the middle thereof.

From the reservoir 70 is also a pump passage 74.
Is also extended. A reservoir 70 is provided in the middle of the pump passage 74.
A pump 76 for pumping the brake fluid from is provided. Reference numeral 78 is a suction valve, and 80 is a discharge valve. The pump 76 is a plunger type which is an example of a type in which the brake fluid is intermittently discharged, and is driven by a motor (not shown). The brake fluid discharge port of the pump passage 74 is connected to a portion of the rear wheel brake passage 24 on the master cylinder 10 side of the second solenoid valve 60.

A portion of the reservoir passage 62 between the connection position of the rear wheel brake passage 24 and the third solenoid valve 72 is formed by the return passage 82 so that the master cylinder 10 and the first solenoid valve 30 of the front wheel brake passage 20 are connected. It is connected to the part between. A check valve 84 is provided in the return passage 82. The check valve 84 blocks the flow of the brake fluid in the direction from the master cylinder 10 to the reservoir passage 62, but allows the flow in the opposite direction.

A proportioning valve (hereinafter simply referred to as "P valve") 85 is provided in a portion of the rear wheel brake passage 24 between the connection position of the reservoir passage 62 and the rear wheel brake cylinder 26. . P valve 85
As is well known, before the input pressure (master cylinder pressure or pump discharge pressure) reaches the break point pressure, the input pressure is output as it is as the output pressure, and the rear wheel brake cylinder 26
However, after the input pressure reaches the break point pressure, in order to avoid the rear wheel lock caused by the load movement to the front of the vehicle, the hydraulic pressure obtained by reducing the input pressure at a constant ratio is used as the output pressure. It is transmitted to the brake cylinder 26.

The pump passage 7 of the rear wheel brake passage 24
A pressure reducing device 86 is provided in a portion closer to the master cylinder 10 than the connection position of No. 4 is. The reason for providing the decompression device 86 is as follows. That is, in the conventional braking system, even if a load-sensing proportioning valve is used, especially in a loaded vehicle, the front wheel braking force and the rear wheel braking force are close to 0 (for example, a brake operation). Initially, when braking on a road surface with a low friction coefficient, etc., and the area before the break point of the load-sensitive proportioning valve, etc.) corresponds to the actual distribution line of the braking force with respect to the ideal distribution line. The rear wheel braking force deviates slightly to the side where it decreases, and it becomes impossible to sufficiently increase the rear wheel braking force in a region where the rear wheel is not locked. Such a situation is constant at least in the light braking area regardless of whether the actual distribution line is empty or loaded, and the gradient of the actual distribution line in the light braking area is equal to that when the vehicle is empty. It is caused by the fact that the wheel leading lock is set so as not to occur. Therefore, in order to solve such a situation, it is necessary to prepare a plurality of braking force distributions having different characteristics at least in the light braking region and selectively realize them. Therefore, the applicant of the present invention, in the anti-lock control state, the pump 7
The discharge pressure of 6 is reduced and transmitted to the front wheel brake cylinder 22, the rear wheel brake pressure is relatively increased compared to that in the normal braking state, and the rear wheel braking force is sufficiently increased in the light braking region to shorten the braking distance. Decompression device 8
6 is provided.

The decompression device 86 has a structure in which a first check valve 88 whose valve opening pressure is not substantially 0 and a second check valve 90 whose valve opening pressure is substantially 0 are opposite to each other and arranged in parallel. It is connected. In this embodiment, since the pump 76 is the pressure source in the antilock control state, the first check valve 88 is used.
Functions as a check valve that allows the flow of the brake fluid in the direction from the pump 76 toward the front wheel brake cylinder 22 at a set valve opening pressure or higher.

Here, the master cylinder 10 and the pump 7
6, the flow of the brake fluid between the front wheel brake cylinder 22 and the rear wheel brake cylinder 26 will be described. In the normal braking state, the first solenoid valve 30 is in the demagnetized state, that is, in the open state. Therefore, the brake fluid from the master cylinder 10 is supplied to the front wheel brake cylinder 22 via the first solenoid valve 30, and the first solenoid valve 30 is also supplied. And the second check valve 9
It is also supplied to the rear wheel brake cylinder 26 via 0. Since the valve opening pressure of the second check valve 90 is substantially 0, in the end,
Front wheel brake cylinder 22 and rear wheel brake cylinder 26
Brake pressures of the same height are generated at and.

On the other hand, in the antilock control state,
While the first solenoid valve 30 is in the excited state, that is, the closed state, the brake fluid discharged from the pump 76 is supplied to the front wheel brake cylinder 22 via the first check valve 88, while the rear wheel brake cylinder 26 (P valve 85) is supplied as it is. Since the valve opening pressure of the first check valve 88 is not substantially 0, the pressure that is lower than the rear wheel brake pressure by the valve opening pressure of the first check valve 88 is eventually supplied to the front wheel brake cylinder 22. Become.

That is, in the normal braking state, the master cylinder 10 functions as a pressure source to generate equal brake pressures in the front wheel brake cylinder 22 and the rear wheel brake cylinder 26, respectively, while in the antilock control state. The pump 76 functions as a pressure source to generate a brake pressure in the front wheel brake cylinder 22 and the rear wheel brake cylinder 26 such that the front wheel brake pressure is lower than the rear wheel brake pressure. As a result, the front-rear braking force distribution of the vehicle is optimized, and in the loaded state, the rear-wheel braking pressure, that is, the rear-wheel braking force can be effectively increased from the light braking region which is the region below the break point of the P valve 85. , The braking distance is shortened.

The reservoir 70 and the master cylinder 10 are connected to each other by an auxiliary passage 92. An inflow control valve 94 is provided in the auxiliary passage 92. The inflow control valve 94 is a pilot type that operates a reservoir piston in the reservoir 70 as a pilot piston.

The reservoir 70 and the inflow control valve 94 are shown in FIG.
As shown in the enlarged view of FIG. A large diameter hole 202 and a small diameter hole 204, both of which have a bottom, are coaxially formed in the housing 200.
The small diameter hole 204 is opened on the bottom surface of the large diameter hole 202. The large diameter hole 202 and the small diameter hole 204 are separated from each other by a partition member 206. Partition member 20
6 is airtightly fixed to the small diameter hole 204 by caulking.

A reservoir chamber 212 is formed in a portion between the reservoir piston 210 and the partition member 206 by fitting the reservoir piston 210 into the large-diameter hole 202 in a substantially airtight and slidable manner. The pump passage 74 and the reservoir passage 62 are connected to the passage 213 communicating with the reservoir chamber 212. In the figure, reference numeral 214 indicates an O-ring as a bidirectional seal member. The open end of the large diameter hole 202 is closed by a plug 215, and a spring 216 as an urging means is arranged between the plug 215 and the reservoir piston 210.

The spring 216 is provided with a reservoir piston 210 via a retainer 218 having a cylindrical shape with a bottom and a bottom.
Is engaged with. Retainer 218 has a large diameter hole 202
Is fitted to the flange of the housing 200.
The limit of access to the reservoir chamber 212 is defined by the contact with the stepped portion of. Therefore, the original position of the retainer 218 defines the normal position of the reservoir piston 210, and when the volume of the reservoir chamber 212 increases, the reservoir piston 210 together with the retainer 218 causes the spring 2 to move.
While compressing 16, 16 is moved from the normal position to the retracted position (volume increasing position). However, since the reservoir piston 210 is loosely fitted to the retainer 218, the reservoir piston 210 can advance independently while leaving the retainer 218 in the original position, and the reservoir chamber 212 can be moved forward.
When the volume of is reduced, only the reservoir piston 210 moves from the normal position to the forward position (volume reduced position).

At the center of the partition member 206, a through hole 220 is formed which connects the reservoir chamber 212 and the space inside the small diameter hole 204 to each other. A tapered and annular valve seat 222 is formed on the end surface of the partition member 206 on the side of the small-diameter hole 204 among the end surfaces of the partition member 206. The through hole 220 is opened in the center of the valve seat 222. Valve seat 222
A spherical valve 224 is seated on the seat.

A cylindrical holding member 230 is coaxially fixed to the same end surface of the partition member 206 in an annular portion located outside the valve seat 222. This holding member 23
0 is a cylindrical valve seat member 2 on the outer peripheral surface thereof.
32 is held airtight and non-separable. Valve seat member 23
2 is also in close contact with the partition member 206. Of the both end surfaces of the valve seat member 232, the end surface opposite to the partition member 206 side is a valve seat 234. The bottomed cylindrical plunger 236 is loosely fitted in the small diameter hole 204,
The bottom of the plunger 236 is made to function as a valve element 238, which is seated on the valve seat 234. An approach limit of the plunger 236 to the valve seat 222 is defined by engagement of the plunger 236 and the holding member 230. Of the space inside the small diameter hole 204, the space partitioned by the bottom of the small diameter hole 204 and the bottom of the plunger 236 is the valve chamber 239, and the housing 200
It is connected to the master cylinder 10 via a passage 240 formed in the above and the auxiliary passage 92.

A spring 242 as an urging means is arranged between the bottom of the plunger 236 and the valve element 224 to prevent the valve element 224 from moving unintentionally. Further, a spring 244 as an urging means is disposed between the bottom of the plunger 236 and the bottom of the small diameter hole 204, and presses the plunger 236 against the valve seat member 232. An engaging portion 246 is formed at the bottom of the plunger 236 so as to project toward the valve element 224 and engage with the valve element 224. The engagement portion 246 allows the plunger 236 to move the valve element 224 to the valve seat 222 in a state where the plunger 236 engages with the valve seat member 232 (approach limit state to the valve seat 222).
The valve element 224 has a height facing the valve seat 222 with an appropriate gap in a state where the valve element 224 and a pin 250 described later are engaged with the engaging portion 246. .

That is, the valve element 224, the valve seat 222 and the spring 242 constitute the first valve assembly 248, and the plunger 236, the valve seat member 232 and the spring 244 constitute the second valve assembly 249. Of. A holder 251 having a bottomed cylindrical shape is fitted inside the small diameter hole 204.
The holding member 232 is held at 1. Holder 25
1 allows the first valve assembly 248 to be fitted into the small-diameter hole 204 in a sub-assembled state (a state where the first valve assembly 248 is assembled prior to the main assembly for assembling the inflow control valve 92). Assembly of the valve assembly 249 is facilitated. A through hole is provided at the bottom of the holder 251, and the liquid passage 240 and the valve chamber 23 are provided.
Communication with 9 is secured.

When the seal between the plunger 236 and the valve seat member 232 is no longer achieved for some reason, the brake fluid from the master cylinder 10 first flows into the reservoir chamber 212 through the following route. . That is, the passage 240, the valve chamber 239, the cylindrical gap between the holder 251 and the plunger 236, the gap between the plunger 236 and the valve seat member 232, the plunger 236 and the valve seat 22.
2 is a space between the valve chamber 252, the valve 224 and the valve seat 2
Then, it flows into the reservoir chamber 212 through the gap between it and the through hole 220 and the through hole 220 in order. Due to this inflow, the reservoir piston 210 is retracted against the spring 216, and the pin 250 is also retracted accordingly, so that the valve element 224 is seated on the valve seat 222, whereby the master cylinder 10 moves to the reservoir chamber. Inflow of brake fluid to 212 is blocked, and pressurization of master cylinder 10 is ensured.

That is, the first valve assembly 248 and the second valve assembly 249 move from the master cylinder 10 to the reservoir 70.
Normal braking conditions as long as they are arranged in series with each other along the flow of the brake fluid in the direction toward and the seal of the second valve assembly 249 is achieved even if the seal of the first valve assembly 248 is not achieved. Since the master cylinder 10 can be boosted in pressure, the reliability of the brake system is improved despite the use of the inflow control valve 94.

The valve element 224 and the reservoir piston 210 are engaged with each other via a pin 250 as a linking member. The pin 250 engages the valve 224 with the reservoir piston 210 in the normal position shown, thereby
The pin 250, the valve element 224, and the plunger 236 are brought into a state of engaging with each other. When the reservoir piston 210 advances from its normal position, the pin 250 also advances, causing the pin 250 to move the plunger 236 against the spring 244 and away from the valve seat member 232.

Therefore, in the normal braking state, the elastic force of the spring 244 causes the plunger 23 to move.
6 is in close contact with the valve seat member 232, and blocks inflow of brake fluid from the master cylinder 10 to the reservoir 70. Therefore, the master cylinder 10 is in a state in which the pressure can be raised, and when the driver depresses the brake pedal 14, hydraulic pressure is generated in the master cylinder 10, and the hydraulic pressure is transmitted to both brake cylinders 22 and 26 to operate the brake. .

On the other hand, when the traction control is started and the pump 76 is operated, the brake fluid in the reservoir chamber 212 is pumped up by the pump 76, so that the reservoir chamber 212 becomes negative pressure and the reservoir piston 210. Moves (forward) from the normal position to the volume reduction position. Along with this, the pin 250 moves the plunger 236 via the valve element 224 in the direction in which the spring 242 is compressed. As a result, the plunger 236 separates from the valve seat member 232, and the master cylinder 10 moves to the reservoir 7 side.
Brake fluid can flow to zero. Therefore, even if the brake fluid is insufficient in the reservoir chamber 212, the brake fluid from the master cylinder 10 is replenished in the reservoir chamber 212, so that the pressure increase of the front wheel brake cylinder 22 is ensured.

The end portion of the pin 250 on the side closer to the valve 224 is a large diameter portion 250a, and the other portion is a small diameter portion 250b. Since the through holes 220 have the same cross section, the gap between the outer peripheral surface of the large diameter portion 250a of the pin 250 and the inner peripheral surface of the through hole 220 is closer to the outer peripheral surface of the small diameter portion 250b and the through hole 220. It is smaller than the gap between the inner surface of the. The reservoir piston 210 moves slightly forward from the normal position, and the plunger 236 moves the valve seat member 23.
2 is slightly separated from the large diameter portion 250a
Is located in the through hole 220 and increases the flow resistance of the brake fluid in the direction from the master cylinder 10 to the reservoir chamber 212. On the other hand, in the state in which the reservoir piston 210 has greatly advanced from the normal position and the plunger 236 has been largely separated from the valve seat member 232, the large diameter portion 250
a is disengaged from the through hole 220 and enters the valve chamber 252 having a diameter larger than that of the through hole 220, and only the small diameter portion 250b is penetrated through the through hole 2
20 inside the reservoir chamber 2 from the master cylinder 10.
The flow path resistance of the brake fluid in the direction toward 12 is reduced.

During the traction control, the reservoir chamber 212 tends to have a negative pressure, so that the reservoir piston 210 advances from the normal position. At this time, since the large-diameter portion 250a of the pin 250 is located in the through hole 220 to increase the flow path resistance, the reservoir chamber 212 is maintained even if the viscosity of the brake fluid is low because the temperature of the brake fluid is high. A sufficient amount of inflow to the reservoir chamber 212 is not secured, and the negative pressure tendency of the reservoir chamber 212 increases. Therefore, the reservoir piston 210 further advances, the large diameter portion 250a enters the valve chamber 252 side, and the flow path resistance is reduced. Along with this, the valve element 224 and the plunger 236 move in a direction in which the spring 244 is compressed. As a result, the valve 224 and the plunger 236.
However, as compared with the case where the large diameter portion 250a does not exert the throttling action, the large diameter portion 250a moves to a position further away from the seated position. That is, the valve 22 during traction control
4 and the plunger 236 are lifted by the large diameter portion 250.
It is increased as compared with the case where the throttling action of a is not exhibited.

Therefore, in this state, the brake pedal 1
When 4 is depressed, the plunger 236 moves by the hydraulic pressure generated in the master cylinder 10 until it is seated on the valve seat member 232.
As compared with the case where there is no diaphragm action of a, it moves with a longer stroke. The long stroke of the plunger 236 means that the stroke of the reservoir piston 210 is long, which means that the amount of brake fluid that can be discharged from the master cylinder 10 to the reservoir chamber 212 is large. Therefore, the brake switch 260 is in the OFF state when the brake pedal 14 is in the non-acting position, and is in the ON state when the brake pedal 14 is in the acting position (stepping position).
The stroke of the brake pedal 14 required to switch the output signal (see FIG. 1) from the OFF state to the ON state can be easily secured, the brake operation can be detected quickly, and the traction control can be ended quickly. To be

That is, in this embodiment, the pin 25
0 in cooperation with the valve chamber 252 and the through hole 220.
It constitutes an example of the "flow path resistance control mechanism" in the invention.

In addition, when the traction control is switched to the anti-lock control, the third solenoid valve 72 is opened at the beginning of the anti-lock control so that the front wheel brake cylinder 22 and the rear wheel brake cylinder 26 are depressurized. At this time, not only the brake fluid in the front wheel brake cylinder 22 and the rear wheel brake cylinder 26 but also the brake fluid in the reservoir chamber 212 is returned to the master cylinder 10 via the third solenoid valve 72. In the present embodiment, during the previous traction control, the reservoir piston 210
Is kept in the advanced position as much as possible to keep the volume of the reservoir chamber 212 as small as possible, and the brake fluid accumulated in the reservoir chamber 212 at the end of the traction control is made as small as possible. Therefore, in this embodiment, a small amount of the brake fluid is returned to the master cylinder 10 at the beginning of the antilock control after the transition from the traction control.

The first solenoid valve 30, the second solenoid valve 60, the third solenoid valve 72, and the pump 76 described above are connected to the controller 300. The controller 300 is mainly composed of a computer. Various programs for executing antilock control and traction control are stored in the ROM thereof, and the CPU executes the various programs while utilizing the RAM to execute antilock control and traction control.

The anti-lock control is a control for preventing each wheel from locking when the vehicle is braked, and each brake cylinder is monitored while monitoring the rotation speed of each wheel and the traveling speed of the vehicle body via a speed sensor (not shown). The hydraulic pressure of 22, 26 is controlled.

During the antilock control, the first solenoid valve 30 is kept closed and the pump 76 is kept operating. Therefore, during the anti-lock control, it is possible to increase and decrease the pressure of the brake cylinders 22 and 26 by the pump 76 irrespective of the master cylinder 10.
Kickback to the driver is avoided.

The pressure increase / decrease of the brake cylinders 22 and 26 is
This is performed by controlling the second solenoid valve 60 and the third solenoid valve 72. There are four combinations of switching states of the second solenoid valve 60 and the third solenoid valve 72, as shown in the following table.

[0051]

[Table 1]

Therefore, in this embodiment, both the second solenoid valve 60 and the third solenoid valve 72 are kept open (indicated by "O" in the drawing) to reduce the pressure of the front wheel brake cylinder 22 and to brake the rear wheel brakes. The cylinder 26 is decompressed, and the second solenoid valve 60 is kept open and the third solenoid valve 72 is kept closed (represented by "C" in the figure) to increase the pressure of the front wheel brake cylinder 22 and the rear wheels. The pressure of the brake cylinder 26 is increased, and the pressure of the front wheel brake cylinder 22 is increased and the rear wheel brake cylinder 26 is held by keeping both the second electromagnetic valve 60 and the third electromagnetic valve 72 in the closed state. Further, the second solenoid valve 60 is kept closed and the third solenoid valve 72 is kept open to increase the pressure of the front wheel brake cylinder 22 and the rear wheel brake cylinder 26. Decompression is performed.

Further, in the present embodiment, the duty control of the second solenoid valve 60 is performed with the third solenoid valve 72 kept closed, whereby the pressure increase gradient of the front wheel brake cylinder 22 and the pressure increase of the rear wheel brake cylinder 26 are increased. The slope is controlled. The second solenoid valve 60 with the first solenoid valve 30 kept closed
Is opened, the brake fluid discharged from the pump 76 is supplied to both the front wheel brake cylinder 22 and the rear wheel brake cylinder 26, and the front wheel brake cylinder 22 and the rear wheel brake cylinder 26 are gradually increased in pressure. By contrast, closing the second solenoid valve 60 while keeping the first solenoid valve 30 closed means that the brake fluid discharged from the pump 76 is supplied only to the front wheel brake cylinder 22. It means that the front wheel brake cylinder 22 is suddenly increased in pressure and the rear wheel brake cylinder 26 is maintained. Therefore, by controlling the duty of the second solenoid valve 60, the pressure increasing gradient of the front wheel brake cylinder 22 and the pressure increasing gradient of the rear wheel brake cylinder 26 can be freely controlled.

On the other hand, the traction control is a control for suppressing the left and right front wheels, which are the drive wheels, from idling when the vehicle is driven. The pump 76 is operated and the rotational speeds of the left and right front wheels, which are the drive wheels, are transmitted via a speed sensor. Also, the hydraulic pressure of the front wheel brake cylinder 22 is controlled while monitoring the traveling speed of the vehicle body.

The traction control ends when any of the following conditions is satisfied. Release of the accelerator pedal (not shown) as an acceleration operation member. The brake switch 260 detects the depression of the brake pedal 14. It is judged that the anti-lock control should be started for the rear wheels belonging to the same brake system as the brake system to which the front wheel currently being subjected to traction control belongs, out of the two brake systems. The state that the slip amount of the left and right front wheels is less than the set value must continue for the set time or longer.

Each solenoid valve 30 in the traction control,
There are four combinations of switching states of 60 and 72, as shown in the following table.

[0057]

[Table 2]

In the initial stage of traction control, the first
The solenoid valve 30 is closed, the second solenoid valve 60 is also closed, and the third solenoid valve 72 is also closed. As a result, the front wheel brake cylinder 22 is boosted by the pump 76, and the brake is operated to cause an excessive amount. The drive torque is reduced.

In the latter half of the traction control, the third
By controlling the duty of both the first solenoid valve 30 and the second solenoid valve 60 while keeping the solenoid valve 72 closed, the pressure increase gradient of the front wheel brake cylinder 22 is controlled. However, in the present embodiment, when the first solenoid valve 30 is in the open state, the second solenoid valve 60 is in the closed state, and when the first solenoid valve 30 is in the closed state, the second solenoid valve 60 is in the open state. Thus, the duty control of these solenoid valves 30 and 60 is performed.

The first solenoid valve 30 is open, the second solenoid valve 60
In the front wheel open-rear wheel closed state, the brake fluid discharged from the pump 76 is the front wheel brake cylinder 22.
Since there is both a tendency to flow into the master cylinder 10 that is at atmospheric pressure and a tendency to flow into the master cylinder 10 at atmospheric pressure, the front wheel brake cylinder 22 shows a tendency of pressure reduction or pressure retention.

On the other hand, when the first solenoid valve 30 is in the closed state and the second solenoid valve 60 is in the open state, with the front wheels closed and the rear wheels open, the brake fluid discharged from the pump 76 tends to flow into the front wheel brake cylinder 22. And the tendency to flow into the rear wheel brake cylinder 26. On the other hand, the rear wheel brake cylinder 26 is connected to the master cylinder 10 by the return passage 82.
Is equal to the hydraulic pressure of the master cylinder 10, that is, the atmospheric pressure, but the flow passage resistance when the brake fluid from the pump 76 is supplied to the rear wheel brake cylinder 26 is increased by the second solenoid valve 60. Therefore, most of the brake fluid from the pump 76 is supplied to the front wheel brake cylinder 22. Therefore, in the front wheel closed-rear wheel open state, the front wheel brake cylinder 22 tends to increase pressure.

Therefore, in this embodiment, the front wheel brake cylinder 22 is gradually increased in pressure by alternately repeating the front wheel open-rear wheel closed state and the front wheel closed-rear wheel open state, and the front wheel The duty ratio, which is the ratio of the time occupied by the front wheel open-rear wheel closed state or the front wheel closed-rear wheel open state, is changed in the control cycle in which the open-rear wheel closed state and the front wheel closed-rear wheel open state are performed once. As a result, the gradually increasing pressure gradient of the front wheel brake cylinder 22 is appropriately controlled in relation to the slip ratios of the left and right front wheels.

When the brake operation is performed during the traction control, the brake fluid from the master cylinder 10 passes through the first electromagnetic valve 30 and the front wheel brake cylinder each time the front wheel is opened and the rear wheel is closed. 22 only. Therefore, while the traction control is being performed, the front wheel brake cylinder 22 is pressure-increased according to the driver's intention, and the front wheel braking force is increased. Further, since the brake fluid from the master cylinder 10 is consumed by the front wheel brake cylinder 22, the depression stroke of the brake pedal 14 increases, and the depression of the brake pedal 14 can be quickly detected by the brake switch 260.
As a result, the traction control can be quickly ended in response to the start of the brake operation.

When the brake operation is performed during the traction control, the brake fluid from the pump 76 is supplied only to the rear wheel brake cylinder 26 each time the front wheel is closed and the rear wheel is opened. Since the discharge pressure of the pump 76 matches the hydraulic pressure of the master cylinder 10, the front wheels are closed-
The brake fluid in the master cylinder 10 is not supplied to the rear wheel brake cylinder 26 each time the rear wheel open state is entered, but the rear wheel brake cylinder 26 is pressurized. Therefore, while the traction control is being performed, the rear wheel brake cylinder 26 is increased in pressure according to the driver's intention, and the rear wheel braking force is increased. On the other hand, as described above, the traction control ends even when it is determined that the anti-lock control should be started for the rear wheels, so that the brake operation during the traction control causes the relationship between the rear wheel brake pressure and the friction coefficient of the road surface. If the value becomes excessively large, the traction control will be ended with this as a trigger.

That is, in the present embodiment, during traction control, duty control is performed so that the first electromagnetic valve 30 and the second electromagnetic valve 60 are in opposite states, so that even during traction control. The vehicle braking is ensured according to the driver's intention, and the traction control is terminated as early as possible in response to the braking operation.

The presence of the time when the first solenoid valve 30 is opened during the traction control also brings about the following effects. In the traction control, if the first solenoid valve 30 is kept closed and the second solenoid valve 60 is kept closed to increase the pressure of the front wheel brake cylinder 22 and the open state is used to reduce pressure, the second solenoid valve 60 should be opened. If a failure occurs in which the first solenoid valve 30 continues to be in the closed state without switching to the first solenoid valve 30, the first solenoid valve 30 is not opened during the traction control.
The brake fluid is filled under high pressure between the front wheel brake cylinder 22 and the second solenoid valve 60. In contrast,
In the present embodiment, the front wheel brake cylinder 22 is depressurized by opening the first solenoid valve 30 during the traction control. Therefore, even if the second solenoid valve 60 becomes inoperable when the second solenoid valve 60 is closed, the first solenoid valve 30 and the front wheels are opened by opening the first solenoid valve 30. Since the brake fluid existing between the brake cylinder 22 and the second solenoid valve 60 can return to the master cylinder 10 via the first solenoid valve 30,
Despite the failure of the second solenoid valve 60, the front wheel brake cylinder 22 is not kept at high pressure during traction control.

Further, in the present embodiment, in the traction control, by depressing both the first solenoid valve 30 and the second solenoid valve 60, the front wheel brake cylinder 22 is depressurized.

As is clear from the above description, in this embodiment, the front wheel brake cylinder 22 constitutes an example of the "brake cylinder" in the invention of each claim, and the first solenoid valve 30 is the "electromagnetic opening / closing". An example of a valve,
Further, the first solenoid valve 30 and the second solenoid valve 60 constitute an example of “electromagnetic hydraulic pressure control device”, the brake switch 260 constitutes an example of “brake operation detecting means”, and the controller 300 is It constitutes an example of a “controller”.

Although the invention of each claim has been specifically described based on the illustrated embodiments, various modifications, based on the knowledge of those skilled in the art, can be made without departing from the scope of the claims. It goes without saying that the inventions of the respective claims can be carried out in an improved mode.

[Brief description of drawings]

FIG. 1 is a system diagram showing a diagonal dual system anti-lock / traction type brake system which is an embodiment common to the inventions of claims 1 and 2. FIG.

2 is a reservoir 70 and an inflow control valve 9 in FIG.
It is sectional drawing which expands and shows 4.

[Explanation of symbols]

 10 Master Cylinder 22 Front Wheel Brake Cylinder 26 Rear Wheel Brake Cylinder 30 First Solenoid Valve 60 Second Solenoid Valve 70 Reservoir 76 Pump 94 Inflow Control Valve 300 Controller

Claims (2)

[Claims] 1. A master cylinder for generating hydraulic pressure by operating a brake operating member by a driver, a brake cylinder for driving wheels connected to the master cylinder by a main passage, and a normally open valve provided in the main passage. An electromagnetic on-off valve and a reservoir connected to the master cylinder by an auxiliary passage, and a reservoir chamber in which a reservoir piston is fitted in a housing in a substantially airtight and slidable manner to store a reservoir liquid in the housing. Is formed, the reservoir piston is displaced from the normal position to the volume increasing position when the volume of the reservoir chamber is increased from the normal value, and is displaced from the normal position to the volume decreasing position when the volume is decreased from the normal value; Valve that is installed in the seat and blocks the flow of brake fluid from the master cylinder to the reservoir when seated. In the state where the master cylinder has a valve seat and no hydraulic pressure is generated, the valve element is seated on the valve seat when the reservoir piston is in the volume increasing position, and the valve element is separated from the valve seat when the reservoir piston is in the volume decreasing position. In a state where hydraulic pressure is generated in the master cylinder, an inflow control valve having a valve seat seated on a valve seat, the reservoir, and a portion of the main passage between the electromagnetic opening / closing valve and the brake cylinder are connected. A pump provided in a pump passage for pumping brake fluid from a reservoir, a brake operation detecting means for detecting a brake operation by a driver, and an electromagnetic hydraulic pressure control device including the electromagnetic opening / closing valve while operating the pump when the vehicle is driven. Traction control for preventing the drive wheels from idling by controlling the hydraulic pressure of the brake cylinder via the brake operation. A brake system including a controller that terminates traction control in response to an output means detecting a brake operation, wherein the controller controls the electromagnetic hydraulic pressure control device while operating the pump when the vehicle is driven. The brake system is characterized in that the traction control is executed by performing control including a time when the vehicle is in an open state. 2. A master cylinder for generating hydraulic pressure by operating a brake operating member by a driver, a brake cylinder for driving wheels connected to the master cylinder by a main passage, and a normally open valve provided in the main passage. A solenoid chamber and a reservoir connected to the master cylinder by an auxiliary passage, and a reservoir chamber in which a reservoir piston is fitted in a housing in a substantially airtight and slidable manner to store a reservoir liquid in the housing. Is formed, the reservoir piston is displaced from the normal position to the volume increasing position when the volume of the reservoir chamber is increased from the normal value, and is displaced from the normal position to the volume decreasing position when the volume is decreased from the normal value; Valve that is installed in the seat and blocks the flow of brake fluid from the master cylinder to the reservoir when seated. In the state where the master cylinder has no hydraulic pressure and the valve seat, the valve element is seated on the valve seat when the reservoir piston is in the volume increasing position, and the valve element is separated from the valve seat when the reservoir piston is in the volume decreasing position. In a state where hydraulic pressure is generated in the master cylinder, an inflow control valve in which a valve seats on a valve seat, the reservoir, and a portion of the main passage between the electromagnetic opening / closing valve and the brake cylinder are connected. A pump provided in a pump passage for pumping brake fluid from a reservoir, a brake operation detecting means for detecting a brake operation by a driver, and an electromagnetic hydraulic pressure control device including the electromagnetic opening / closing valve while operating the pump when a vehicle is driven. Traction control for preventing the drive wheels from idling by controlling the hydraulic pressure of the brake cylinder via the brake operation. In a brake system including a controller that terminates traction control in response to an output means detecting a brake operation, a state in which a valve element of the inflow control valve is located near a valve seat out of a valve seat. Then, the brake system is provided with a flow path resistance control mechanism that increases the flow path resistance of the brake fluid in the direction from the master cylinder to the reservoir and decreases the flow path resistance at a distant position.