JPS58110349A - Liquid pressure control device for rear wheel brake - Google Patents

Abstract

PURPOSE:To idealize brake force for rear wheels, by controlling liquid pressure for rear wheel brakes by means of a solenoid valve with the use of a master liquid pressure sensor, a rear wheel liquid pressure sensor and front and rear wheel load sensors. CONSTITUTION:A solenoid valve 22 is arranged between a master cylinder 10 and wheel cylinders 20 for rear wheel brakes, and is controlled by a control circuit 32 provided with a microcomputer. A master liquid pressure sensor 30, a rear wheel liquid pressure sensor 26, a front wheel load sensor 28 and a rear wheel load sensor 30 are connected to the control circuit 32. The control circuit 32 calculates ideal rear wheel brake force in accordance with signals from these sensors, for controlling the solenoid valve 22. Rear wheel brake force may be idealized suitably in accordance with load and liquid pressure, since rear wheel liquid pressure is controlled by the solenoid valve.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hydraulic pressure control device for rear wheel brakes, and in particular,
The present invention relates to a hydraulic control device that can accurately obtain rear wheel braking force in accordance with ideal distribution characteristics between front wheel braking force and rear wheel braking force.

When the vehicle is braking, the rear wheels may lock due to the load shift, which may impair the stability of the vehicle during braking. Therefore, in order to obtain as large a braking force as possible on the left rear wheel while preventing the rear wheel from locking, the rear wheel braking force is adjusted so that the rear wheel braking force can be obtained in accordance with the ideal distribution characteristics between the front wheel braking force and the rear wheel braking force. It is desirable that the brake fluid pressure supplied to the wheel brakes be suppressed.

However, conventional hydraulic pressure control devices prevent the brake hydraulic pressure from being supplied to the rear wheel brakes in a predetermined braking state r or above, or prevent the brake hydraulic pressure from being supplied to the mask cylinder at a certain level. Since the pressure is reduced at a certain rate, it is difficult to accurately match the rear wheel braking force to the ideal distribution characteristic, and there is the disadvantage that suitable rear wheel braking force cannot necessarily be obtained in all braking conditions. Ta. That is, according to such a conventional hydraulic pressure control device, the relationship between the front wheel braking force and the rear wheel braking force can generally only be expressed by two straight lines with a break point in the middle. This is because the ideal distribution characteristic is represented by a smooth curve.

The present invention was made against the background of the following two circumstances, and its purpose is to obtain rear wheel braking force that more accurately matches the ideal distribution characteristics between front wheel braking force and rear wheel braking force. An object of the present invention is to provide a hydraulic pressure control device for rear wheel brakes.

In order to achieve such an object, the rear wheel brake hydraulic pressure control device of the present invention reduces the braking force supplied to the rear wheel brakes from the mask cylinder, thereby reducing the front wheel braking force and the rear wheel braking force of the vehicle. This is a rear wheel brake hydraulic pressure control device that adjusts the ratio of: (1) Detects the brake hydraulic pressure generated in the mask cylinder described in 1'11■ and outputs a mask hydraulic pressure signal representing the brake hydraulic pressure.
(2) a rear fluid pressure sensor that detects the brake fluid pressure supplied to the rear wheel brake and outputs a rear fluid pressure signal representing the brake fluid pressure; (3) the front wheel brake; The mask hydraulic pressure signal is determined from a predetermined fixed functional relationship between the brake hydraulic pressure generated in the mask cylinder and the target brake hydraulic pressure of the rear wheel brake in order to obtain an ideal distribution between the braking force and the rear wheel braking force. (4) a control device that sequentially calculates a target brake fluid pressure according to changes in the mask cylinder and the rear fluid pressure signal, and outputs a suppression signal when the brake fluid pressure represented by the rear fluid pressure signal exceeds the target brake fluid pressure; A fluid that is inserted into a fluid passage connecting the rear wheel brake, opens and closes between the mask cylinder and the rear wheel brake according to the suppression signal, and causes the brake fluid pressure of the rear wheel brake to follow the target brake fluid pressure. and a pressure control valve.

In this way, the target braking fluid pressure is successively calculated from the predetermined constant functional relationship according to changes in the braking fluid pressure of the mask cylinder, and the braking fluid pressure supplied to the rear wheel brakes is Since the control is performed to follow the target braking hydraulic pressure, a suitable rear wheel braking force can be obtained that accurately follows the ideal BH distribution characteristic between the front wheel braking force and the rear wheel braking force.

Another aspect of the rear wheel brake hydraulic pressure control device is as follows: (1) A mask hydraulic pressure control device that detects the brake hydraulic pressure generated in the mask cylinder and outputs a mask hydraulic pressure signal representing the brake V hydraulic pressure. a sensor; (2) a rear fluid pressure sensor that detects brake fluid pressure supplied to the rear wheel brake and outputs a rear fluid pressure signal representing the brake fluid pressure; and (3) a load applied to the front wheels of the vehicle. (4) A rear wheel load sensor that detects a load applied to the rear wheels of a vehicle and outputs a rear wheel load signal representing the load. (5) In order to obtain the ideal distribution of the front wheel braking force and the rear wheel braking force of the vehicle, the brake fluid pressure generated in the mask cylinder and the target brake fluid pressure of the rear wheel brake, including the transfer load and rear wheel load as variables. Based on a predetermined fixed functional relationship between (6) a control device that sequentially calculates the brake fluid pressure of the rear wheel brake represented by the rear fluid pressure signal and outputs a suppression signal when the brake fluid pressure of the rear wheel brake represented by the rear fluid pressure signal exceeds the target brake fluid pressure; (6) the mask cylinder and the rear brake fluid; a hydraulic pressure control valve that is inserted in a fluid passage connecting the mask cylinder and the rear wheel brake according to the suppression signal, and causes the brake hydraulic pressure of the rear wheel brake to follow the target brake hydraulic pressure. It is characterized by including.

In this way, the target braking hydraulic pressure is successively calculated from the predetermined constant functional relationship based on the front wheel load signal, the rear wheel load signal, and the mask hydraulic pressure signal according to the change in the mask hydraulic pressure signal. At the same time, the brake fluid pressure supplied to the rear wheel brakes is controlled to follow the target brake fluid pressure. The wheel braking force is obtained depending on the vehicle load and its loading position.

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below based on the drawings.

In FIG. 1, the mask cylinder 10 is equipped with a first hydraulic pressure chamber 14 and a second hydraulic pressure chamber 16 in which equal braking hydraulic pressure is generated in accordance with the operation of the brake pedal 12.
1. The pressure chamber 14 is connected to the wheel cylinder 18 of the front wheel brake, and the second hydraulic pressure chamber 16 is connected to the wheel cylinder 20 of the rear wheel brake with an electromagnetic on-off valve 2 which is a hydraulic pressure control valve.
Connected via 2. The vehicle has a second hydraulic pressure chamber 16
a master hydraulic pressure sensor 24 that is connected to detect the brake hydraulic pressure generated in the mask cylinder 10 and outputs a mask hydraulic pressure signal MP representing the brake hydraulic pressure, and the wheel cylinder 20.
A rear fluid pressure sensor 26 is connected to the rear fluid pressure sensor 26, which detects the brake fluid pressure supplied to the rear wheel brakes, and outputs a rear fluid pressure signal 1 (, P) representing the brake fluid pressure, and a rear fluid pressure sensor 26 that outputs a rear fluid pressure signal 1 (, P) representing the brake fluid pressure, and a rear fluid pressure sensor 26 that detects the brake fluid pressure supplied to the rear wheel brakes. A front wheel load sensor 28 and a rear wheel load sensor 30 are provided which detect the front wheel load and output a front wheel load signal FW and a rear wheel load signal RW representing the front wheel load and the rear wheel load, respectively.

These mask hydraulic pressure signal MP, post-infusion pressure signal]
2, the suppression signal SL is output to the electromagnetic on-off valve.

The control circuit 32 is configured with a digital circuit as shown in FIG. 2, and receives the mask hydraulic pressure signal MP and the post-infusion pressure signal 1 (P A, /D converter 3 respectively
4. Similarly, the front wheel load signal FW and the rear wheel load signal RW output from the front wheel load sensor 28 and the rear wheel load sensor 30 are each filtered through a low-pass filter 86.
The signal is supplied to the A/D converter 34 via 88. The low-pass filters 36 and 38 are noise-removing low-pass power filters composed of operational amplifiers, capacitors, resistors, and the like.

The A/D converter 34 converts analog signals into digital code signals, and converts the input mask hydraulic pressure signal MP, rear infusion pressure signal RP, front wheel load signal FW, and rear wheel load signal RW into digital codes. Convert each to a signal,
CPU 40. RAM42. R
Supplies OM44 and I10 port 46.

CP [J40 is an arithmetic and control unit, and ROM4
In addition to executing arithmetic control using the storage function of RAM 42 according to a program stored in advance in I1.
It outputs a signal to the outside through the 0 port 46 and receives an external signal.

The I10 port 46 is connected to a brake switch 48 which is activated when the brake pedal 12 is operated, and is supplied with a pedal operation signal SP indicating that the brake pedal/L'12 has been operated. . and,
A suppression signal SL (drive current) is supplied from the I10 port 46 to the electromagnetic on-off valve 22 via the driver 50.

The electromagnetic on-off valve 22 closes the fluid passage from the second hydraulic pressure chamber 16 of the mask cylinder 10 to the wheel cylinder 20 in accordance with the suppression signal SL, so that the braking hydraulic pressure supplied to the wheel cylinder 20 is suppressed. That is, the third
As shown in the figure, a first port 72 communicating with the second hydraulic pressure chamber 16 and a second port 74 communicating with the wheel cylinder 20 are formed in a housing 76, and a valve cover 78 is formed in the housing 76. By being screwed together, a valve chamber 80 connecting the first port 72 and the second port 74 is formed. A poppet valve 86 urged toward a valve seat 84 by a spring 82 is accommodated in the valve chamber 80, and when the poppet valve 86 is seated on the valve seat 84, the second port 74 and the valve chamber 80 are connected. It seems like the communication between the two is being cut off.

Inside the housing 76, there is a cylindrical solenoid 90 fixed by a lower cover 88 screwed to the bottom of the housing 76, and a non-magnetic solenoid fixed liquid-tightly to the lower cover 88 and inserted into the solenoid 90. sleeve 92 and sleeve 9
A cylindrical core 94 is provided which is fitted within the poppet valve 2 for axial movement and abuts against the poppet valve 86. A spring 8 is provided between the core 94 and the lower lid 88.
A spring 96 is inserted to move the poppet valve 86 and the core 94 against the biasing force of 2.

Therefore, in the electromagnetic on-off valve 22, when the solenoid 90 is not energized, the poppet valve 86 is separated from the valve seat 84, and the first port 72 and the second port 74 are communicated with each other.
When the solenoid 90 is energized via the lead wire 92, the core 94 is attracted against the urging force of the spring 96, and the poppet valve 86 is seated on the valve seat 84, and the first port 72 and the second port 74 are connected to each other. The gap is now cut off. Note that when the pressure in the second port 74 becomes higher than the pressure in the valve chamber 80, the poppet valve 86 is separated from its seat against the biasing force of the spring 82, so the electromagnetic on-off valve 22 also functions as a check valve. We are prepared. Furthermore, a through hole 98 is formed in the core 94 to pass through it in the axial direction in order to equalize the pressure on both end faces of the core 94, so that the operation of the core 94 is not inhibited by the brake fluid pressure.

The operation of this embodiment will be explained below.

With the operation of the brake pedal/L'12, the control circuit 32
operates according to the flowchart shown in FIG.

The first step S1 is executed, and the operating state of the brake clutch 48 is determined. If the brake pedal 12 is not operated and the pedal operation signal SP has not yet been generated, step S1 is repeated.

Brake pedal/L'12 is operated and pedal operation signal S
Once P is provided to CP [J 40 via I/Q port 46, steps S2 to S5 are performed.

In step S2, the front wheel load Wf and the rear wheel load Wr represented by the front wheel load signal FW and the rear wheel load signals B and W are
is read, and in step S3, the actual braking fluid pressure (hereinafter referred to as mask fluid pressure) M generated in the mask cylinder 10 represented by the mask fluid pressure signal MP and the actual braking fluid pressure of the wheel cylinder 20 represented by the post-transfusion fluid pressure signal RP are calculated. The braking hydraulic pressure (hereinafter referred to as rear wheel hydraulic pressure) R is read. 14- Then, in step S4, the front wheel load Wr is determined.

Based on the rear wheel load Wr and the master hydraulic pressure M, a target braking hydraulic pressure 'P-X' is calculated. In other words, front wheel braking force B
Basic formula expressing the ideal distribution relationship between r and rear wheel braking force Br; Here, h is the height of the center of gravity of the vehicle, and l is the wheel base, both of which are constants.

and the relational expression showing the braking force and braking fluid pressure; % formula % (2) (8) Here, a and b are constants.

The front wheel load wf and the rear wheel load Wr obtained from the above are used as variables, and the mask hydraulic pressure M and the target braking hydraulic pressure R are calculated.

A calculation program that calculates a predetermined constant function equation representing the relationship between Target brake fluid pressure R based on pressure M
x is calculated.

Then, in step S5, it is determined whether the post-infusion fluid pressure B1 is greater than the target braking fluid pressure Rx.

If the post-infusion pressure R is smaller than the target braking fluid pressure Rx,
Steps S6 and S7 are executed, the output of the suppression signal SL is blocked and the electromagnetic on-off valve 22 is maintained in an open state, and in the case of a brake switch, the electromagnetic on-off valve 22 is
The process is executed again from step s1 via step S8 in which the brake valve/L'12 is maintained in an open state, but if the operation of the brake pedal/L'12 is continued and the brake operation signal SP is continuously generated, the process is executed again from step S3. executed.

Then, when the rear wheel, nv n, exceeds the target brake fluid pressure R, steps S9 and S7 are executed. That is, in step S9, the suppression signal SL is supplied from the I10 port 46 to the electromagnetic on-off valve 22 via the driver 50, so that the space between the second hydraulic chamber 16 and the wheel cylinder 20 is closed, and the rear wheel brake is activated. The brake fluid pressure supplied to the mask fluid pressure M is immediately made equal to the target brake fluid pressure R, regardless of the increase in the mask fluid pressure M, and the operations from step S7 onwards are repeated in the same manner as described above.

In the above control cycle, in step S5, the target braking fluid pressure Rx corresponding to the change in the mask fluid pressure M is calculated continuously and sequentially, so that the post-infusion fluid pressure R is made to immediately follow the target braking fluid pressure R,. , as shown by the solid line in Figure 5,
A distribution characteristic between the front wheel braking force and the rear wheel braking force that matches the ideal distribution line can be obtained according to the front wheel load and the rear wheel load of the vehicle. Strictly speaking, the distribution characteristics shown in FIG. 5 obtained by this example change in stages for each control cycle, but since the control cycle time is an extremely small value (high speed), the distribution characteristics shown in FIG. It becomes a curve.

Therefore, the conventional load sensing type hydraulic control valve (LSPV)
According to the above, as shown by the broken line in FIG. 5, the distribution characteristic = 17- is formed by two straight lines connecting at the break points, whereas the distribution characteristic of this example corresponds to the ideal distribution characteristic. Since the rear wheel braking force is constructed from a curved line, rear wheel braking force that more accurately follows the ideal distribution characteristic can be obtained depending on the loaded load and its loading position. That is, the above (
Since Equation 4) incorporates the front wheel load and the rear wheel load as variables, it is possible to obtain a rear wheel braking force that corresponds to changes in the loading position of the load.

As described above, according to the present embodiment, the front wheel load Wf1 is
Rear wheel load Wr 1Target braking fluid pressure 1 (x) is calculated continuously and sequentially based on the master fluid pressure M, so that the braking fluid pressure supplied to the rear wheel brakes follows the target braking fluid pressure R, As a result, a rear wheel braking force that more accurately follows the ideal distribution characteristic can be obtained depending on the load and its position.

Further, since the electromagnetic on-off valve 22 is configured to open when the power is not energized, operation of the rear wheel brake is ensured even in the event of a failure of the control circuit 32, the solenoid 90, etc., and there is an advantage of high safety.

Furthermore, according to this embodiment, the load sensor 28930 and the electromagnetic on-off valve 22, which is a hydraulic pressure control valve, have no mechanical relationship with each other and can be installed at their own locations.
Unlike conventional load-sensing hydraulic control valves, there is no need to attach it to the suspension part that senses the load.

Therefore, there is an advantage that a single type of hydraulic pressure control valve can be used in common for most vehicle types without having to have various shapes for each vehicle type.

Although the embodiment of the present invention has been described above based on the drawings, the present invention can also be applied to other embodiments.

For example, the brake fluid pressure generated in the mask cylinder 10 is
For example, it is configured to be transmitted to the wheel cylinders 18 and 20 of each wheel through a so-called two-system X-shaped pipe consisting of a pipe that connects the right front wheel and the left rear wheel, and a pipe that connects the left front wheel and the right rear wheel. Of course, it is good to do so. In such a case, it is necessary to connect a hydraulic pressure control valve to each wheel cylinder 20, but if the post-infusion pressure is controlled for each wheel cylinder 20 by the hydraulic pressure control device of the present invention, extremely high precision can be achieved. Since the hydraulic pressure control operation can be obtained evenly on the left and right sides, there is an advantage that the braking force on the left and right rear wheels can be obtained more evenly.

The electromagnetic opening/closing valve 22 may be one that can control the brake fluid pressure supplied to the wheel cylinder of the rear brake according to the suppression signal sL, so even if it has no check valve function but a simple opening/closing function. No problem.

The aforementioned control circuit 32 may be partially or entirely constituted by a so-called microcomputer,
The microcomputer can also be used for other purposes at the same time.

The load sensors 28 and 3o described above detect the relative movement between the vehicle body and the unsprung member by utilizing the deformation of the front and rear wheel suspension systems, respectively, and detect the fluid pressure of the pneumatic suspension system and the vehicle height adjustment system. It may be configured to detect each of the front wheels and the rear wheels.

In the flowchart of FIG. 4, reading of the front wheel load and rear wheel load in steps S1 and S2 may be done in advance by other timing signals generated in a stable state of the vehicle, or the post-infusion pressure in step S3 Reading of R may be executed after step S5.

In equation (4) for calculating the target brake fluid pressure RX in the above-mentioned embodiment, the height h of the center of gravity is set as a constant, and the relationship between the braking force of the brake and the brake fluid pressure supplied to it is expressed simply. Although a proportional formula was used, the height of the center of gravity h was determined by a linear function of the rear wheel load Wr (h = KWr +
p+q-However, Ill.

q is a constant), and the relationship between braking force and brake fluid pressure is expressed as a linear function equation (for example, Br=axM+b, where a and b are constants) or a quadratic function equation (for example, Br-a xM2+b).
XM-1-C (where a, b, and c are constants) may also be used. In this case, there is an advantage that the calculation accuracy of the target brake hydraulic pressure R is further improved.

In the above-mentioned embodiment, in the case of a vehicle in which the carrying load of the vehicle does not change that much, the calculation program of equation (4) with the front wheel load 21-wr and the rear wheel load wr as constants is stored in advance, and from that equation It is also good as a control device that calculates the target braking fluid pressure It according to the mask fluid pressure M. In this case, there is an advantage that the load sensors 28 and 30 are not required and the calculation program is simple.

It should be noted that the above is just one embodiment of the present invention,
The present invention can be modified in various ways without departing from its spirit.

As described in detail above, according to the rear wheel brake hydraulic pressure control device of the present invention, the target brake fluid is adjusted according to changes in the brake fluid pressure of the mask cylinder based on a predetermined constant functional relationship for obtaining the ideal distribution. The pressure is calculated sequentially, and the brake fluid pressure supplied to the rear wheel brakes is controlled to follow the target brake fluid pressure, so the ideal distribution of front wheel braking force and rear wheel braking force is accurately achieved. Thus, a suitable rear wheel braking force can be obtained.

In another aspect, the front and rear wheel loads of the vehicle and the mask are determined from a predetermined functional relationship including the front wheel load and rear wheel load as variables to obtain the ideal distribution characteristic. The target brake fluid pressure is successively calculated based on the brake fluid pressure generated in the cylinder, and the brake fluid pressure supplied to the rear wheel brakes is controlled to follow the target brake fluid pressure. 1/i for rational distribution characteristics between braking force and rear wheel braking force! l) The rear wheel braking force is
It is obtained depending on the load of the vehicle and its loading position.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing the configuration of an embodiment of the present invention. FIG. 2 is a block diagram showing the electrical configuration of the embodiment of FIG. 1. FIG. 3 is a sectional view showing the hydraulic pressure control valve of the embodiment shown in FIG. FIG. 4 is a 70-chart illustrating the operation of the control device of the embodiment of FIG. FIG. 5 is a distribution characteristic diagram illustrating the operation of the embodiment shown in FIG. 10: Mask cylinder 22: Electromagnetic on-off valve (hydraulic pressure control valve) 24: Master hydraulic pressure sensor 26: Post-infusion pressure sensor 28: Front wheel load sensor 3o: Rear wheel load sensor 32: Control circuit (control device) Applicant Toyota Jidosha Kogyo Co., Ltd. 4-3] Figure 4

Claims (1)

[Claims] (1) A rear wheel brake hydraulic pressure control device that adjusts the ratio of front wheel braking force and rear wheel braking force of a vehicle by suppressing the brake fluid pressure supplied to the rear wheel brakes from a mask cylinder, comprising: a mask hydraulic pressure sensor that detects brake hydraulic pressure generated in the mask cylinder and outputs a mask armpit pressure signal representing the brake hydraulic pressure; and a mask hydraulic pressure sensor that detects the brake hydraulic pressure supplied to the rear wheel brake and outputs a mask armpit pressure signal representing the brake hydraulic pressure; A rear infusion pressure sensor that outputs a rear infusion pressure signal representing From a predetermined fixed functional relationship, a target brake fluid pressure is successively calculated according to changes in the mask armpit pressure signal, and when the brake fluid pressure represented by the rear@hydraulic pressure signal exceeds the target brake fluid pressure. a control device that outputs a suppression signal; and a control device that is inserted into a fluid passage connecting the mask cylinder and the rear wheel brake, and opens and closes between the mask cylinder and the rear wheel brake in accordance with the suppression signal, and controls the rear wheel brake. A hydraulic pressure control device for a rear wheel brake, comprising: a hydraulic pressure control valve that causes brake hydraulic pressure to follow the target brake hydraulic pressure. r2) A rear wheel brake hydraulic pressure control device that adjusts the ratio between the front wheel braking force and the rear wheel braking force of a vehicle by suppressing the brake fluid pressure supplied to the rear wheel brakes from a mask cylinder, wherein the mask a mask hydraulic pressure sensor that detects the brake fluid pressure generated in the cylinder and outputs a 77-ta hydraulic pressure signal representing the brake fluid pressure; and a mask fluid pressure sensor that detects the brake fluid pressure supplied to the rear wheel brake and outputs the brake fluid pressure. a rear infusion pressure sensor that outputs a rear infusion pressure signal representing the load; a front wheel load sensor that detects the load applied to the front wheels of the vehicle and outputs a front wheel load signal representing the load; A rear wheel load sensor that detects and outputs a rear wheel load signal representing the load, and a mask that includes the front wheel load and rear wheel load as variables to obtain the ideal distribution of the front wheel braking force and rear wheel braking force of the vehicle. From a predetermined fixed functional relationship between the brake fluid pressure generated in the cylinder and the target brake fluid pressure of the rear wheel brake, Jj (
Then, the target brake fluid pressure supplied to the rear wheel brakes is successively calculated in accordance with the change in the mask fluid pressure signal, and the brake fluid pressure of the @transfusion brake represented by the rear fluid pressure signal is equal to the target brake fluid. A control device that outputs a suppression signal when the pressure exceeds the pressure is inserted in a fluid passage connecting the mask cylinder and the rear wheel brake, and opens and closes between the mask cylinder and the rear wheel brake in accordance with the suppression signal. A hydraulic pressure control device for a rear wheel brake, comprising: a hydraulic pressure control valve that causes the brake hydraulic pressure of the rear wheel brake to follow the target brake hydraulic pressure.