JPH0344021B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention generates a braking assist force for a vehicle, thereby increasing the braking force to obtain a vehicle braking force greater than the vehicle braking force obtained from the pedal force applied by the driver. Relating to power devices.

(Prior art) Conventionally, as a brake booster, the
184056 (and others such as Utility Model Application Publication No. 120157/1983) is known, and is generally called a booster or vacuum booster.

To explain its action briefly, when the brake pedal is depressed, the valve plunger connected to the valve operating rod moves forward, and this forward movement closes the vent hole drilled in the power piston with the vacuum valve, and the valve plunger is connected to the valve operating rod. A negative pressure chamber and an atmospheric pressure chamber are defined within the cylinder.
Then, when you press the pedal further, the air valve opens while the vacuum valve remains closed.
Atmospheric air is sent into the atmospheric pressure chamber, and the power piston moves forward due to the pressure difference between the atmospheric pressure chamber and the negative pressure chamber, and a push rod attached to the power piston pushes the piston of the master cylinder.

In other words, it is a device that can increase braking force by assisting the force that pushes the piston of the master cylinder before the master cylinder.

However, in such conventional brake boosters, the ratio between the magnitude of the pedal force input to the brake pedal and the magnitude of the output transmitted from the push rod to the master cylinder is always constant; The problem was that the feeling of brake effectiveness was poor at the initial stage of depression, and the brake feeling was poor due to the poor feeling of brake bite, especially when driving at low speeds.

Moreover, the problem of poor brake effectiveness during initial braking is that the input/output characteristics between the input applied to the brake pedal and the output transmitted to the master cylinder do not appear linear due to mechanical reasons. The output was extremely unstable with respect to the input, which became even more noticeable because the output was not sufficient.

Therefore, in order to improve the feeling of brake effectiveness at the initial stage of depression of the brake pedal, a proposal was made to provide the brake booster with a jump-up characteristic (a characteristic in which the output suddenly rises in response to the input) during the initial braking. There is.

However, if the amount of jump-up is constant regardless of the vehicle speed, it will certainly have a good initial feeling when braking from low speeds, but conversely, it will have a good feeling when braking from high speeds. When braking, the wheels lock, making it difficult to control the vehicle, resulting in a brake feeling that gives a sense of danger.

(Objective of the Invention) The present invention has been made to solve the above-mentioned problems, and its purpose is to increase the jump-up amount at low speeds and to reduce the jump-up amount at high speeds. To provide a brake booster capable of changing a jump-up amount according to vehicle speed and obtaining ideal brake feeling regardless of vehicle speed.

(Structure of the Invention) That is, in order to achieve the above-mentioned object, the present invention includes a booster having a variable pressure chamber and a constant pressure chamber and interposed between a master cylinder and a brake pedal;
A brake booster comprising: a fluid pressure supply source communicated with a variable pressure chamber of the booster; and a valve device disposed in a communication pipeline between the fluid pressure supply source and the variable pressure chamber, and operated by a valve drive signal. , a pedal force detection means for detecting a pedal force applied to a brake pedal and outputting a pedal force signal; a vehicle speed detection means for detecting a vehicle speed and outputting a vehicle speed signal; calculates an ideal jump-up amount such that the jump-up amount of the braking force is large during initial braking and becomes smaller as the vehicle speed signal increases, and outputs an ideal braking-force signal when the pedal force signal is input. an ideal braking force signal generating means for detecting an actual vehicle braking force, and a braking force detecting means for detecting an actual vehicle braking force and outputting a braking force signal;
a comparator that inputs the ideal braking force signal and the braking force signal, outputs a valve drive signal so that the braking force signal matches the ideal braking force signal, and causes the valve device to perform a valve opening/closing operation; It was configured with the following.

(Effects of the Invention) Therefore, since the brake booster of the present invention is configured as described above, the jump up amount is large at low speeds and small at high speeds. In addition, the amount of jump-up can be changed according to the vehicle speed, and the brake effect feeling at the initial stage of depression of the brake pedal can be improved regardless of the vehicle speed, and the brake feeling that gives a sense of danger can be eliminated.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.
In describing this embodiment, a brake booster for an automobile will be taken as an example.

First, the configuration of the first embodiment of the present invention shown in FIG. 1 will be explained.

1 is a booster, and in its shell 101 there is a power piston 103 which is biased by a return spring 102 and can freely slide back and forth, an input rod 104 provided on the end surface of the power piston 103 on the inside side of the passenger compartment, and a power piston. A push rod 105 provided on the outer side end surface of the vehicle interior, a diaphragm 108 interposed between the power piston 103 and the shell 101 and partitioned into a variable pressure chamber 106 and a constant pressure chamber 107, and a diaphragm 108 opened to the variable pressure chamber 106. It includes a fluid pressure communication port 109 and a negative pressure communication port 110 that opens into the constant pressure chamber 107.

And this booster 1 is push rod 1
The brake pedal 3 is interposed between a master cylinder 2 provided at the end of the input rod 104 and a brake pedal 3 provided at the end of the input rod 104.

Note that from the master cylinder 2 there are fluid pressure pipes 4,
5 is piped to the wheel cylinders 61, 7 of the front and rear wheel brake units 6, 7, 8, 9.
1, 81, and 91 so that hydraulic pressure is transmitted to them.

10 and 11 are a high pressure source and a negative pressure source as fluid pressure supply sources, and this high pressure source 10 and negative pressure source 11
The fluid pressure from the pressure chamber 10 passes through a valve device 12 (described later), passes through communication pipes 13, 14, and 15, and reaches the variable pressure chamber 10.
6.

12 is a valve device, and a first solenoid valve 12a is formed in a normally closed state by a spring 121.
and a second solenoid valve 12b which is normally closed by a spring 122, one first solenoid valve 12a communicates with the high pressure source 10 through a through hole 123, and the other second solenoid valve 12a communicates with the high pressure source 10 through a through hole 123. 12b side is communicated with the negative pressure source 11 through a through hole 124, and an opening hole 126 is formed in a partition plate 125 that partitions both electromagnetic valves 12a and 12b.
6, the first solenoid valve 12a
is closed, and the second solenoid valve 12b is opened and the negative pressure source 1
Either the fluid pressure from the high pressure source 10 is introduced into the variable pressure chamber 106 by opening the first solenoid valve 12a and the second solenoid valve 12b is closed, or the fluid pressure from the high pressure source 10 is introduced into the variable pressure chamber 106 by opening the first solenoid valve 12a and closing the second solenoid valve 12b. 12a and 12b are closed to maintain the pressure in the variable pressure chamber 106.

Reference numeral 17 denotes a strain gauge as a pedal force detection means, which is attached to the surface of the input rod 104 and detects the pedal force applied to the brake pedal 3 based on axial strain, and generates an electrical signal having a certain relationship with the brake pedal force. is output as a pedal force signal a.

Reference numeral 18 denotes vehicle speed detection means, which detects the speed of the vehicle using a speedometer system or the like and outputs a vehicle speed signal b as an electrical signal corresponding to the vehicle speed.

Reference numeral 19 denotes an ideal differential pressure signal generating means, which stores in advance braking force characteristics in the form of a function or a numerical table in which characteristics of different jump-up amounts depending on the vehicle speed are selected or generated upon receiving the input of the vehicle speed signal b. The ideal jump-up amount is calculated by calculation. This ideal jump-up amount is set such that when the vehicle speed signal b is a low vehicle speed signal, the jump-up amount of the braking force during initial braking is large, and as the vehicle speed signal becomes a high vehicle speed signal, the jump-up amount becomes smaller. Specifically, as shown in Figures 2 and 3, the input/output ratio is set to be 1:1.2 or higher regardless of vehicle speed, and the jump-up feeling is maintained when braking even when driving at high speed. I'm trying to get a feel for it.

In this ideal differential pressure signal generating means 19, when the pedal force signal a is input, the second
As shown in Figure 3 and Figure 3, the input/output characteristics are as follows:
It jumps up at the initial stage of depression of the brake pedal 3 (section A in the figure), and then doubles the force in the brake pedal force range up to a predetermined level (section B in the figure).
Area where the brake pedal force is even greater (section C in the diagram)
When the brake is turned on, the input/output ratio is set to 1:1 and an ideal braking force signal is output in the form of an ideal differential pressure signal c to prevent brake locking and the like.

20 and 21 are pressure sensors as an example of braking force detection means, one first pressure sensor 20 is arranged in the communication pipe 15 and detects the pressure on the variable pressure chamber 106 side, and the other second pressure sensor Reference numeral 21 is arranged in the constant pressure chamber 107 of the booster 1 to detect the pressure in the constant pressure chamber 107.

A differential pressure signal d between the pressures measured by the pressure sensors 20 and 21 is output as a braking force signal to a comparator 16, which will be described later.

16 is a comparator which inputs the ideal differential pressure signal c as the ideal braking force signal and the differential pressure signal d as the actual braking force signal, and this differential pressure signal d is the ideal differential pressure signal c. The valve drive signal e is outputted so as to match the valve drive signal e, and the valve device 12 is caused to perform the valve opening/closing operation as described above.

Note that the ideal differential pressure signal generating means 19 and the comparator 16 are constituted by a microcomputer, and both 19 and 16 are formed by the control device 22.

Next, the effect will be explained.

To explain with reference to the flowchart of the first embodiment device shown in FIG. 4, the vehicle speed signal b detected by the vehicle speed detection means 18 and the pedal force signal a detected by the strain gauge 17 which is the pedal force detection means. In response to this, the brake operation is first checked depending on whether the pedal force signal a is zero or if a pedal force is being applied.If the pedal force is zero, the brake operation is simply checked by returning to vehicle speed detection.

However, the pedal force signal a indicates that pedal force is being applied.
If so, an ideal jump-up amount is calculated according to the vehicle speed, and an ideal differential pressure Pi for obtaining this ideal jump-up amount is calculated as a value according to the pedal force detected.

Incidentally, the above-mentioned functions except for vehicle speed detection and pedal force detection are performed by the ideal differential pressure signal generating means 19. Then, the above-mentioned ideal differential pressure Pi and actual differential pressure P are compared by the comparator 16, and if the ideal differential pressure Pi is large, high pressure fluid is introduced from the high pressure source 10 into the pressure transformation chamber 106, and the ideal differential pressure Pi and the actual differential pressure P are compared. If the actual differential pressure P is the same, the valve device maintains the fluid pressure in the variable pressure chamber 106, and if the ideal differential pressure Pi is low, the valve device introduces negative pressure fluid from the negative pressure source 11 into the variable pressure chamber 106. 12, the jump-up amount at the initial stage of braking corresponding to the target vehicle speed is realized by the first embodiment.

As mentioned above, in the brake booster of the first embodiment, as shown in FIG. 3, the amount of jump-up is large during braking operation from low-speed driving, and a good brake with a feeling of bite is obtained as a brake feeling. Feeling is obtained, and
As shown in FIG. 2, when braking from high-speed driving, the amount of jump-up is small, and a good brake feeling can be obtained without the feeling of danger due to the steering wheel locking up and being released.

Although not shown, since the jump-up amount is determined in accordance with the vehicle speed even in the intermediate range from low speed to high speed, it goes without saying that good brake feeling can be obtained over the entire vehicle speed range.

Next, a second embodiment shown in FIG. 5 will be described.

In this embodiment, a deceleration sensor 23 is used as a braking force detecting means for detecting an actual vehicle braking force, and a deceleration signal f from this deceleration sensor 23 is converted into an ideal deceleration signal f from an ideal deceleration signal generating means 24. signal g
This is an example different from the first embodiment in that the valve device 12 is configured to output a valve drive signal e.

In other words, since the actual braking force is based on deceleration, the braking force is detected including the influence of the vehicle weight. This is a preferable example since the braking force will not be excessive in vehicles such as the above.

Note that other configuration effects are the same as those in the first embodiment, so their explanations will be omitted here.
The flowchart of the second embodiment shown in FIG. 6 differs from the first embodiment only in that the valve device 12 is switched by comparing the actual deceleration α and the ideal deceleration αi. different.

Although the brake booster of the present invention has been described above in detail with reference to embodiments, the specific configuration is not limited to these embodiments.For example, the booster may be a single type booster or a tandem type booster. However, the present invention is not limited to the structure of the embodiment, as long as it has a variable pressure chamber and a constant pressure chamber, and can perform a boosting action by the pressure difference between the two chambers.

In addition, the fluid pressure supply limits include negative pressure, atmospheric pressure,
It may be any positive pressure, and the fluid pressure is not limited to gas pressure such as air or gas, but also includes liquid pressure such as water or oil.

Further, although a switching valve having an electromagnetic valve structure is shown as the valve device, it is not limited to the switching valve, but may be a valve device having a pressure regulating valve structure that can adjust the pressure from a fluid pressure supply source using a valve drive signal.

Further, as the pedal force detection means, it is sufficient that the pedal force applied to the brake pedal can be directly or indirectly detected, and other than the strain gauge in the embodiment, a means for detecting based on the stroke amount of the input rod, the amount of depression of the brake pedal, etc. may be used. It may be hot.

In addition, in the example, as an actual braking force signal,
Although the differential pressure signal between the booster's variable pressure chamber and the constant pressure chamber and the vehicle deceleration signal were used as the braking force signal, there are other factors related to braking force between the brake pedal and the occurrence of deceleration, such as master cylinder pressure and valves. The actual braking force signal may be obtained by detecting various elements such as hydraulic pressure singly or in combination.

[Brief explanation of drawings]

Fig. 1 is a diagram showing a brake booster according to the first embodiment of the present invention, Fig. 2 is a brake input/output characteristic diagram during high-speed running according to the first embodiment, and Fig. 3 is a diagram showing the brake booster according to the first embodiment. A brake input/output characteristic diagram during low speed driving, FIG. 4 is a flowchart explaining the operation of the device of the first embodiment, FIG. 5 is a diagram showing the brake booster of the second embodiment, and FIG. 6 is a diagram showing the brake booster of the second embodiment. FIG. 7 is a flowchart showing the operation of the second embodiment device. 1... Booster, 106... Transformation room, 107...
... Constant pressure chamber, 2 ... Master cylinder, 3 ... Brake pedal, 10 ... High pressure source (fluid pressure supply source), 1
1... Negative pressure source (fluid pressure supply source), 12... Valve device,
16...Comparator, 17...Strain gauge (pedal force detection means), 18...Vehicle speed detection means, 19...Ideal differential pressure signal generation means (ideal braking force signal generation means), 20,
21...pressure sensor (braking force detection means), 23...
... Deceleration sensor (braking force detection means), 24... Ideal deceleration signal generation means (ideal braking force signal generation means), a... Pedal force signal, b... Vehicle speed signal, c...
Ideal differential pressure signal (ideal braking force signal), d...differential pressure signal (braking force signal), e...valve drive signal, F...deceleration signal (braking force signal), g...ideal deceleration signal ( ideal braking force signal).

Claims (1)

[Claims] 1. A booster having a variable pressure chamber and a constant pressure chamber and interposed between a master cylinder and a brake pedal;
A brake booster comprising: a fluid pressure supply source communicated with a variable pressure chamber of the booster; and a valve device disposed in a communication pipeline between the fluid pressure supply source and the variable pressure chamber, and operated by a valve drive signal. , a pedal force detection means for detecting a pedal force applied to a brake pedal and outputting a pedal force signal; a vehicle speed detection means for detecting a vehicle speed and outputting a vehicle speed signal; calculates an ideal jump-up amount such that the jump-up amount of the braking force is large during initial braking and becomes smaller as the vehicle speed signal increases, and outputs an ideal braking-force signal when the pedal force signal is input. an ideal braking force signal generating means for detecting an actual vehicle braking force, and a braking force detecting means for detecting an actual vehicle braking force and outputting a braking force signal;
a comparator that inputs the ideal braking force signal and the braking force signal, outputs a valve drive signal so that the braking force signal matches the ideal braking force signal, and causes the valve device to perform a valve opening/closing operation; A brake booster characterized by comprising: