JP3570437B2 - Negative pressure booster - Google Patents

Description

[0001]
[Industrial applications]
The present invention relates to a vacuum booster , and more particularly, to a vacuum booster suitable for use in a mechanical braking device that constitutes a vehicle braking system together with a regenerative braking device .
[0002]
[Prior art]
Conventionally, as a braking system for braking a vehicle , a mechanical braking device having a brake booster that boosts the depression force of a brake pedal, a sensor for detecting an operation state of the brake pedal, and a brake detected by the sensor 2. Description of the Related Art A regenerative braking device that increases or decreases a regenerative braking force in accordance with an increase or decrease in a pedal operation amount is known (Japanese Patent Laid-Open No. 2-123902).
It is also known that a stroke amount is detected instead of the depression force of the brake pedal, and the regenerative braking force is increased or decreased according to the increase or decrease of the stroke amount of the brake pedal.
Further, as the brake booster, a valve body slidably provided in a shell, a valve plunger slidably fitted to the valve body and linked with an input shaft, and a first valve seat formed on the valve body. A second valve seat formed in the valve plunger, a valve body seated on the first valve seat and the second valve seat, and a non-operating valve body against a forward force due to atmospheric pressure applied to the valve body. A negative pressure type brake booster comprising: a return spring for biasing the valve plunger and the valve body; and a spring for biasing the valve plunger and the valve body to a non-operating position against a forward force due to atmospheric pressure applied to the valve plunger and the valve body. The device is already known.
In this type of braking system, until the mechanical braking device operates, the regenerative braking force is increased or decreased in accordance with the increase or decrease in the pedal effort or stroke amount of the brake pedal, that is, in accordance with the increase or decrease in the operation amount of the brake pedal. When the mechanical braking device starts braking and outputs a braking force, the regenerative braking force is kept constant. Therefore, the increase / decrease of the regenerative braking force by only the regenerative braking device and the increase / decrease of the total braking force of the regenerative braking force and the mechanical braking force can be smoothly continued.
[0003]
[Problems to be solved by the invention]
However, in the above-described conventional braking system, the regenerative braking force is increased in accordance with the increase in the operation amount of the brake pedal only until the mechanical braking device starts braking. Therefore, the regenerative braking force at the time of starting can not be increased, and the regenerative braking force by the regenerative braking device cannot be used effectively.
That is, in order to increase the regenerative braking force when the mechanical braking device starts braking and to effectively use the regenerative braking force, it is necessary to set the mechanical braking device to start braking only by giving a large operation amount. For this purpose, increase the set load of the return spring of the master cylinder or hydraulic booster that constitutes the mechanical braking device, or increase the stroke amount until the master cylinder or hydraulic booster starts operating. Should be increased.
However, if such a setting is made, in the unlikely event that the regenerative braking device does not operate, the braking force by the mechanical braking device will not be obtained until the brake pedal is largely operated, and the braking force will not be obtained. Feels ineffective. Further, since the maximum value of the regenerative braking force is not always constant and varies depending on the number of revolutions of the drive motor driving the vehicle , the maximum regenerative braking force can be obtained if the set load or the stroke amount is too large. In some cases, the mechanical braking device does not start operating, and the brake feeling deteriorates.
In view of such circumstances, the present invention provides a negative pressure type in which the braking force of the regenerative braking device can be effectively used while the braking force of the mechanical braking device is immediately obtained by depressing the brake pedal. A booster is provided .
[0004]
[Means for Solving the Problems]
That is, the present invention provides a valve body slidably provided in a shell, a part of which protrudes from the shell, a valve mechanism provided in the valve body, an input shaft for switching and controlling the valve mechanism, A return spring mounted between the shell and the valve body to bias the valve body to a non-operating position;
The valve mechanism includes a first valve seat formed on the valve body, a valve plunger slidably fitted on the valve body and interlocking with the input shaft, and a second valve seat formed on the valve plunger. A valve body that comes into contact with and separates from the first valve seat and the second valve seat, and a spring that is elastically mounted between the valve body and the input shaft and urges the valve plunger and the valve body to a non-operating position. In a negative pressure booster equipped with
The value obtained by subtracting the forward force due to the differential pressure between the atmospheric pressure and the vacuum pressure acting on the valve element and the valve plunger from the urging force of the spring is the atmospheric pressure and the vacuum pressure acting on the valve body from the urging force of the return spring. by having greater than a value obtained by subtracting the forward force by the differential pressure between, when added input to the input shaft, against the return spring before the switching operation of the flow path of the valve mechanism is performed above The valve body moves forward.
[0005]
[Action]
According to the negative pressure booster having the above-described configuration, when an input is applied to the input shaft, the switching operation of the flow path is performed by the valve mechanism including the first valve seat, the second valve seat, the valve element plunger, and the valve element. The valve body advances only by the above input before the boosting action is obtained, but in the conventional vacuum booster, when the input is applied to the input shaft, the switching operation of the flow path is immediately performed by the valve mechanism. The boosting action and the above input caused the valve body to move forward.
Therefore, according to the braking system for a vehicle including the mechanical braking device using the negative pressure booster and the regenerative braking device of the present invention, the braking force can be obtained by the mechanical braking device as soon as the brake pedal is depressed. but becomes, so that initially the increase in the braking force that does not utilize vacuum booster, until the start of a strong braking by vacuum booster, its effective to increase the regenerative braking force by the regenerative braking device It can be used. If the regenerative braking device does not operate, the mechanical braking device immediately generates a braking force by depressing the brake pedal. It is possible to prevent the brake feeling from being deteriorated as much as possible.
[0006]
【Example】
The present invention will be described below with reference to the illustrated embodiment. In FIG. 1, a braking system for a vehicle includes a mechanical braking device 2 for increasing and decreasing a mechanical braking force in accordance with an increase and a decrease in a depression force of a brake pedal 1, A regenerative braking device 3 for increasing or decreasing the regenerative braking force according to the increase or decrease of the stroke amount is provided.
The mechanical braking device 2 includes a conventionally known negative pressure type brake booster 5 (hereinafter referred to as a negative pressure type booster) . The negative pressure type booster 5 includes a pump and the like driven by a motor (not shown). A negative pressure is supplied from a negative pressure supply source 6 through a negative pressure passage 7. The input shaft 8 of the vacuum booster 5, Yes coupled above the brake pedal 1 which is swingably supported about the pin 9, the vacuum booster 5 via the brake pedal 1 The operation amount applied to the input shaft 8 can be boosted and transmitted to the master cylinder 10. The brake fluid pressure generated by the master cylinder 10 is supplied to the wheel cylinders 12 of the respective wheels 11 so that a mechanical braking force can be generated.
Next, the regenerative braking device 3 performs a regenerative braking operation at the time of braking by using a drive motor 13 that drives a vehicle , as is well known in the art. A control device 15 is provided for inputting a signal from a sensor 14 for detecting an amount. The control device 15 increases the regenerative braking force of the regenerative braking device 3 to the maximum regenerative braking force according to the increase in the stroke amount of the brake pedal 1. It is well known that the maximum regenerative braking force obtained by the regenerative braking device 3 is not always constant, but varies according to the rotation speed of the drive motor 13.
FIG. 2 shows a main part of the negative pressure type booster 5, in which a substantially cylindrical valve body 21 is slidably provided in a shell 20. A conventionally known valve mechanism 25 including a vacuum valve 22 and an atmospheric valve 23 is provided in the valve body 21, and the valve mechanism 25 is operated in conjunction with the input shaft 8. .
The valve mechanism 25 includes a valve plunger 26 slidably fitted to the valve body 21, a first valve seat 21 </ b> A formed on an inner peripheral surface of the valve body 21 and constituting the vacuum valve 22, A second valve seat 26A which is formed at the rear end of the valve member 26 and constitutes the atmospheric valve 23, and a valve body which is further urged by a spring 27 and is seated on the first valve seat 21A or the second valve seat 26A. 28.
The valve plunger 26 and the valve element 28 are held at a non-operating position shown on the right side in FIG. 2 by a spring 30 when the valve element 28 is seated on the second valve seat 26A of the valve plunger 26 by a spring 27. ing. At this time, in a state where the valve body 28 is separated from the first valve seat 21A of the valve body 21, since the vacuum pressure is introduced to the first valve seat 21A side, the valve plunger 26 and the valve body 28 2 is exerted on the left side of FIG. 2 by the atmospheric pressure. Therefore, the spring 30 has a biasing force greater than the forward force, and the valve plunger 26 and the valve plunger 26 are opposed to the forward force. The valve body 28 is biased and held at the inoperative position.
A plate plunger 31 slidably fitted in the valve body 21 is disposed on the front side of the valve plunger 26. A reaction disk 32 facing the plate plunger 31 is provided with a base recessed portion of the output shaft 33. 33A. The output shaft 33 is linked to the piston of the master cylinder 10.
Further, a return spring 34 is elastically mounted between the shell 20 and the valve body 21, and the return spring 34 urges and holds the valve body 21 to a non-operation position. At this time, the right end of the valve body 21 protrudes out of the shell 20 to which the vacuum pressure is introduced, and the atmospheric pressure acts on it. Therefore, the return spring 34 has a biasing force greater than its forward force, and biases and holds the valve body 21 to the inoperative position against the forward force.
However, in this embodiment, the forward force of the valve body 28 and the valve plunger 26 due to the atmospheric pressure is determined by the biasing force of the spring 30, rather than the value obtained by subtracting the forward force of the valve body 21 due to the atmospheric pressure from the biasing force of the return spring 34. The biasing force of the spring 30 is set so that the value obtained by the pulling becomes large.
As an example of specific numerical values, when the urging force of the return spring 34 is 11 kg, the forward force of the valve body 21 due to the atmospheric pressure is 7 kg, and the forward force of the valve plunger 26 and the valve body 28 due to the atmospheric pressure is 1 kg, The biasing force of the spring 30 is set to 6 kg. In this case, a value obtained by subtracting the forward force of the valve body 21 due to the atmospheric pressure from the biasing force of the return spring 34 is 11 kg−7 Kg = 4 kg, and the forward force of the valve body 28 and the valve plunger 26 due to the atmospheric pressure is reduced from the biasing force of the spring 30. The subtracted value is 6 kg-1 kg = 5 kg.
In the above configuration, when the brake pedal 1 is depressed, the control device 15 that has detected the depression by the stroke amount sensor 14 causes the drive motor 13 to perform a regenerative braking action. At this time, the control device 15 increases the regenerative braking force to the maximum regenerative braking force according to the increase in the stroke amount of the brake pedal 1.
On the other hand, in the mechanical braking device 2, when the brake pedal 1 is depressed, the biasing force of the spring 30 is set as described above, so that the return spring 34 bends before the spring 30 bends. Before the mechanism 25 performs the switching operation of the flow path, the valve body 26 is advanced. As a result, when the output shaft 33 moves forward, a brake fluid pressure is generated in the master cylinder 10 so that a braking operation is performed (see a section between points A and B in FIG. 3).
When the brake reaction force is transmitted to the valve body 21 via the output shaft 33 and the reaction disk 32, the reaction force is applied to the urging force of the return spring 34, so that a total force for urging the valve body 21 in the non-operation direction is provided. The momentum is increased, and the spring 30 is eventually bent, so that the valve body 28 is seated on the first valve seat 21A, and the valve body 28 is relatively separated from the second valve seat 26A to switch the flow path of the valve mechanism 25. When this is done, a boosting action by the brake booster can be obtained, and thereby a strong braking action can be obtained (see points B to C in FIG. 3).
The point C in FIG. 3 indicates the point at which the boosting action by the brake booster is maximized, and the dotted line in FIG. 3 indicates the output characteristics of a conventional general brake booster. .
[0007]
【The invention's effect】
As described above, according to the present invention, as soon as the brake pedal is depressed, the braking force can be obtained by the mechanical braking device, but initially the braking force is increased without using the negative pressure booster. Until the powerful braking by the negative pressure type booster is started, the regenerative braking force by the regenerative braking device can be increased and its effective use can be achieved.
In the unlikely event that the regenerative braking device does not operate, the mechanical braking device immediately generates a braking force by depressing the brake pedal. The effect is obtained that the brake feeling can be prevented from being deteriorated as much as possible.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram showing one embodiment of the present invention.
FIG. 2 is a sectional view of a main part of the vacuum booster 5 shown in FIG.
FIG. 3 is a characteristic diagram of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Brake pedal 2 ... Mechanical braking device 3 ... Regenerative braking device 5 ... Negative pressure type brake booster 8 ... Input shaft 21 ... Valve body 21A ... 1st valve seat 25 ... Valve mechanism 26A ... 2nd valve seat 28 ... Valve element 30 ... spring 34 ... return spring

Claims (3)

A valve body slidably provided in the shell, a part of which protrudes from the shell, a valve mechanism provided in the valve body, an input shaft for switching control of the valve mechanism, and a shell and a valve body. A return spring that is elastically interposed between the valve body and biases the valve body to a non-operation position.
The valve mechanism includes a first valve seat formed on the valve body, a valve plunger slidably fitted on the valve body and interlocking with the input shaft, and a second valve seat formed on the valve plunger. A valve body that comes into contact with and separates from the first valve seat and the second valve seat, and a spring that is elastically mounted between the valve body and the input shaft and urges the valve plunger and the valve body to a non-operating position. In a negative pressure booster equipped with
The value obtained by subtracting the forward force due to the differential pressure between the atmospheric pressure and the vacuum pressure acting on the valve element and the valve plunger from the urging force of the spring is the atmospheric pressure and the vacuum pressure acting on the valve body from the urging force of the return spring. by having greater than a value obtained by subtracting the forward force by the differential pressure between, when added input to the input shaft, against the return spring before the switching operation of the flow path of the valve mechanism is performed above A negative pressure type booster characterized in that the valve body moves forward. The value obtained by subtracting the forward force due to the differential pressure between the atmospheric pressure and the vacuum pressure acting on the valve element and the valve plunger from the urging force of the spring is the atmospheric pressure and the vacuum pressure acting on the valve body from the urging force of the return spring. The negative pressure chamber type booster according to claim 1 , wherein the biasing force of the spring is set to be larger than a value obtained by subtracting a forward force caused by a pressure difference between the spring and the spring. The negative pressure booster constitutes a mechanical braking device, and the mechanical braking device including the negative pressure booster constitutes a vehicle braking system together with a regenerative braking device. 3. The vacuum booster according to claim 1, wherein the booster is a vacuum booster.

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