JPH1035473A - Negative pressure type booster - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase an output without any increase of a device size as a whole so as to transmit strong operation force to a master cylinder and the like and to reduce an installation space so as to lower a cost. SOLUTION: An inside of a shell 4 of a booster main body 3 is divided into a negative pressure chamber A and a control pressure chamber B by means of a diaphragm 5, and according to a pressing operation of an input shaft 6 by means of a brake pedal 1, the negative pressure chamber A and the control pressure chamber B are connected/disconnected mutually by means of a control valve mechanism 7. A force, which is obtained by boosting a pressing operation force of the input shaft 6 by means of a differential pressure between the negative pressure chamber A and the control pressure chamber B, is transmitted to a master cylinder 11 from the output shaft 8. In the middle of a negative pressure introducing pipe 9 connecting an intake manifold of an engine to the negative pressure chamber A in the shell 4, a check valve 15, which allows suction of air from the inside of the negative pressure chamber A toward the intake manifold 10 side and prevents its reverse flow, and a negative pressure pump 16, which sucks the air inside the negative pressure chamber A so as to discharge it to the outside and generates a vacuum pressure lower than the negative pressure from the intake manifold 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vacuum booster preferably used for boosting a depressing operation force of a brake pedal or the like by utilizing a negative pressure generated in an intake manifold of a vehicle engine, for example. .

[0002]

2. Description of the Related Art Generally, a diaphragm whose outer peripheral side is attached to the shell and which defines a negative pressure chamber and a control pressure chamber inside the shell and an inner peripheral side of the diaphragm are provided on the inner peripheral side of the diaphragm. A control valve mechanism that communicates and shuts off between the chamber and the control pressure chamber, an input shaft that is depressed via a brake pedal or the like to open and close the control valve mechanism, and a connection between the negative pressure chamber and the control pressure chamber. There is known a negative pressure booster including an output shaft that boosts the pressing operation force of the input shaft by a differential pressure generated therebetween and outputs the boosted operation force to the outside.

In a vacuum booster of this type according to the prior art, for example, a vacuum generated in an intake manifold of an automobile engine is introduced into a vacuum chamber of the shell, and the vehicle is operated until the brake pedal is depressed. When not braking,
For example, the negative pressure chamber and the control pressure chamber are communicated by the control valve mechanism, and both the negative pressure chamber and the control pressure chamber are kept in a negative pressure state.

When the input shaft is depressed by depressing the brake pedal during braking of the vehicle, the control valve mechanism shuts off the negative pressure chamber and the control pressure chamber, and releases the atmospheric pressure to the control pressure chamber side. By introducing this, a differential pressure is generated between the negative pressure chamber in the shell and the control pressure chamber, and the operating force obtained by boosting the depressing force of the brake pedal using the differential pressure at this time is output from the output shaft to the master. Tell the cylinder.

[0005] As a result, the booster can drive the master cylinder with a force boosted from the depressing operation force of the brake pedal, and supplies the brake fluid pressure from the master cylinder to the brake cylinder on each wheel side. Thus, these brake cylinders can apply a braking force to each wheel of the vehicle.

[0006]

In the vacuum booster according to the prior art described above, the vacuum generated in the intake manifold of the engine is directly introduced into the vacuum chamber of the shell through a vacuum pipe or the like. Therefore, only a negative pressure of, for example, about 500 mmHg can be generated in the negative pressure chamber, and there is a problem that a further output cannot be transmitted from the negative pressure booster to the master cylinder.

[0007] In particular, it has been a major problem to improve the output of a negative pressure type booster with an increase in the size of a vehicle.
However, if the entire device is enlarged by simply increasing the size of the negative pressure chamber or the shell, it becomes difficult to secure a mounting space on the engine room side of the vehicle, which causes a problem such as an increase in cost. .

The present invention has been made in view of the above-mentioned problems of the prior art. The present invention can surely improve the output without increasing the size of the whole, and can transmit a large operating force to a master cylinder and the like. , Installation space can be reduced,
It is an object of the present invention to provide a negative pressure booster capable of reducing costs.

[0009]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, a first aspect of the present invention is a shell, and a partition provided in the shell and defining a negative pressure chamber and a control pressure chamber in the shell. A member, a control valve mechanism provided on the partition member for communicating and shutting off between the negative pressure chamber and the control pressure chamber in response to a pressing operation of the input shaft, and a control valve mechanism between the negative pressure chamber and the control pressure chamber. A negative pressure booster comprising an output shaft which boosts the pressing operation force of the input shaft by the differential pressure and outputs the boosted operation force to the outside, and guides a negative pressure generated in an intake manifold of the engine into the negative pressure chamber. A negative pressure conduit connected to the shell, and further provided in the middle of the negative pressure conduit, furthermore than a negative pressure from the intake manifold to increase a differential pressure between the negative pressure chamber and the control pressure chamber. Negative pressure pump means for generating a low negative pressure in the negative pressure chamber; Provided, said allowing the negative pressure chamber side of air flows toward the intake manifold side, adopts a configuration comprising a check valve for preventing the flow of reverse.

[0010] According to the above configuration, by generating a negative pressure even lower than the negative pressure from the intake manifold by the negative pressure pump means, the differential pressure between the negative pressure chamber and the control pressure chamber can be reliably increased. A greater force can be taken from the output shaft by the pressure difference at this time. Further, since a check valve is provided in the middle of the negative pressure conduit between the negative pressure chamber of the booster and the intake manifold, the negative pressure pump means and the negative pressure chamber are further moved from the intake manifold side. Low pressure (negative pressure)
Can be kept in a state.

Further, according to the invention of claim 2, the negative pressure pump means includes a pump housing having a large-diameter cylinder and a small-diameter cylinder, and a slidably provided inside the large-diameter cylinder of the pump housing. A large-diameter piston that reciprocates in the large-diameter cylinder by a differential pressure between the negative pressure and the external atmospheric pressure, and a small-diameter cylinder that reciprocates in the small-diameter cylinder of the pump housing following the large-diameter piston. A small-diameter piston defining a pump chamber and an atmosphere chamber therein, a negative pressure compensating valve for allowing air in the pump chamber to be discharged toward the atmosphere chamber, and preventing a reverse flow, The pump chamber is closed to shut off the pump chamber from the negative pressure chamber in the shell, and communicates the pump chamber with the negative pressure chamber when the pressure in the pump chamber becomes lower than the negative pressure chamber in the shell. Formed by composed of a negative pressure supply valve for.

According to the above construction, when the large-diameter piston repeatedly reciprocates in the large-diameter cylinder of the pump housing due to the differential pressure between the negative pressure from the intake manifold and the atmospheric pressure,
Since the small-diameter piston reciprocates in the small-diameter cylinder of the pump housing following the large-diameter piston, when the small-diameter piston is slid and displaced from the pump chamber toward the atmosphere chamber side, it is more than the negative pressure from the intake manifold. Low pressure (negative pressure) can be generated in the pump chamber.

When the pressure in the pump chamber becomes lower than that of the negative pressure chamber in the shell, the negative pressure supply valve is opened, so that the lower pressure (from the pump chamber to the negative pressure chamber in the shell). Negative pressure). Further, when the small-diameter piston slides from the atmosphere chamber toward the pump chamber, even if the pressure in the pump chamber rises to the atmospheric pressure level, the air in the pump chamber is released by the negative pressure compensating valve at this time. The pump chamber can always be kept at a pressure equal to or lower than the atmospheric pressure.

On the other hand, in the invention of claim 3, the negative pressure pump means is provided slidably in a pump housing having a large-diameter cylinder and a small-diameter cylinder, and in the large-diameter cylinder of the pump housing. A large-diameter piston defining a first pressure chamber and a second pressure chamber inside the cylinder, and a negative pressure introduction formed in the pump housing and for introducing a negative pressure from the intake manifold into the first pressure chamber. And the large-diameter piston is constantly urged from the first pressure chamber side to the second pressure chamber side, and the negative pressure from the negative pressure introduction path causes the first pressure chamber to move to the second pressure chamber. When the pressure becomes lower than that of the chamber, biasing means for allowing the large-diameter piston to slide and displace from the second pressure chamber side toward the first pressure chamber side due to the differential pressure at this time; Slide the inside of the large-diameter cylinder toward the first pressure chamber side. The second pressure chamber is shut off from the outside atmosphere when slidingly displaced to the stroke end, and the large-diameter piston slides in the large-diameter cylinder toward the second pressure chamber toward the stroke end. A first switching valve mechanism for communicating the second pressure chamber with the atmosphere when displaced;
When the large-diameter piston slides in the large-diameter cylinder toward the first pressure chamber toward the stroke end, the first pressure chamber communicates with the second pressure chamber. A second switching valve mechanism for shutting off the first pressure chamber with respect to a second pressure chamber when the inside of the large-diameter cylinder is slid toward the second pressure chamber to a stroke end; A small-diameter piston that slides and displaces in a small-diameter cylinder of the pump housing following the diameter piston to define a pump chamber and an atmosphere chamber in the small-diameter cylinder, and the air in the pump chamber is directed toward the atmosphere chamber. A negative pressure compensating valve that permits discharge and prevents reverse flow; and a valve that is normally closed to shut off the pump chamber from the negative pressure chamber in the shell. Pressure was lower than the negative pressure chamber It constitutes a negative pressure supply valve and for communicating said pump chamber to the negative pressure chamber to.

According to the above construction, when the large-diameter piston is slid to the stroke end in the large-diameter cylinder toward the second pressure chamber, the first switching valve mechanism causes the second pressure chamber to move. Is communicated to the outside atmosphere, and the first and second pressure chambers are shut off by the second switching valve mechanism. Therefore, the first pressure chamber is brought into a negative pressure state by the negative pressure from the negative pressure introduction path, The second pressure chamber can be set at atmospheric pressure, and the large-diameter piston is directed from the second pressure chamber side to the first pressure chamber side by a differential pressure generated between the first and second pressure chambers. The sliding displacement can be performed against the urging means.

When the large-diameter piston slides in the large-diameter cylinder toward the first pressure chamber to the stroke end, the first switching valve mechanism is switched to a valve-closed state. Since the second pressure chamber is shut off from the outside atmosphere and the second switching valve mechanism is switched to the open state to communicate between the first and second pressure chambers, the first and second pressure chambers are connected. Both the chambers can be shut off from the atmosphere to maintain the same pressure state, and the large-diameter piston slides from the first pressure chamber side to the second pressure chamber side by the urging force of the urging means. Can be done.

As a result, the large-diameter piston can be reciprocated in the large-diameter cylinder of the pump housing by the differential pressure between the negative pressure from the intake manifold and the atmospheric pressure, and the small-diameter piston follows the large-diameter piston. By reciprocating in the small-diameter cylinder of the pump housing, when the small-diameter piston is slid and displaced from the pump chamber toward the atmosphere chamber, a pressure (negative pressure) lower than the negative pressure from the intake manifold is generated in the pump chamber. Can be generated.

When the pressure in the pump chamber becomes lower than that of the negative pressure chamber in the shell, the negative pressure supply valve opens, so that the lower pressure (from the pump chamber to the negative pressure chamber in the shell). Negative pressure). Further, when the small-diameter piston slides from the atmosphere chamber toward the pump chamber, even if the pressure in the pump chamber rises to the atmospheric pressure level, the air in the pump chamber is released by the negative pressure compensating valve at this time. The pump chamber can always be kept at a pressure equal to or lower than the atmospheric pressure.

[0019]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

FIGS. 1 to 4 show a case where the negative pressure booster according to the embodiment of the present invention is applied to a brake device of a vehicle.

In the drawing, reference numeral 1 denotes a brake pedal provided in a driver's cab of a vehicle, 2 denotes a negative pressure booster operated by the brake pedal 1, and the negative pressure booster 2 corresponds to FIG.
As shown in FIG. 3, a booster body 3 serving as a negative pressure type booster is provided.
And a negative pressure pump device 14 described later.

Here, the booster main body 3 includes a shell 4 fixed to a board (not shown) or the like on the lower side of the operator's cab, and a negative pressure chamber A having an outer peripheral side attached to the shell 4. And a control pressure chamber B. The diaphragm 5 is provided on the inner peripheral side of the diaphragm 5, and is provided with a negative pressure chamber A and a control pressure chamber in response to a pressing operation of the input shaft 6 by the brake pedal 1. B, a control valve mechanism 7 for communicating and shutting off, and an output shaft 8 for boosting the pressing operation force of the input shaft 6 and outputting the same to the outside by a differential pressure between the negative pressure chamber A and the control pressure chamber B. And so on.

The shell 4 of the booster main body 3 is provided with a connecting pipe 4A at a position communicating with the negative pressure chamber A. The connecting pipe 4A is connected to the intake manifold 10 of the engine through a negative pressure pipe 9. It is connected to the. Then, the negative pressure generated in the intake manifold 10 is further reduced to a lower pressure (hereinafter, referred to as a vacuum pressure) by the negative pressure pump device 14, and the vacuum pressure is guided into the negative pressure chamber A in the shell 4.

On the other hand, the atmospheric pressure is introduced into the control pressure chamber B in the shell 4 via the control valve mechanism 7 when the brake pedal 1 is depressed, and the negative pressure chamber A in the negative pressure state is introduced into the shell 4 into the control pressure chamber B. A large pressure difference is generated between the control pressure chamber B and the control pressure chamber B in the atmospheric pressure state.
The booster body 3 uses the differential pressure between the chambers A and B when the brake pedal 1 is depressed, and uses the output shaft 8 to increase the operation force obtained by boosting the pedal depression force from the output shaft 8 to a master cylinder 11 described later.
Tell

Reference numeral 11 denotes a master cylinder which is operated by the brake pedal 1 via the booster main body 3, and is configured as a tandem master cylinder and has two output ports 11A, 11A. . The master cylinder 11 is provided with a piston (not shown) interlocking with the output shaft 8 of the booster main body 3, and this piston is used to operate the liquid reservoir 1 when the brake pedal 1 is depressed.
2 is supplied as brake fluid pressure from each output port 11A to a brake device (not shown) of the vehicle via each brake pipe 13.

Reference numeral 14 denotes a negative pressure pump device provided in the middle of the negative pressure conduit 9, and the negative pressure pump device 14 is connected to the intake manifold 10 of the engine via one side pipe 9 A of the negative pressure conduit 9. A check valve 15 for allowing the air in the negative pressure chamber A to flow toward the intake manifold 10 and preventing the air from flowing in the reverse direction; and a check valve 15 between the check valve 15 and the negative pressure chamber A of the shell 4. And a negative pressure pump 16 provided as a negative pressure pump means provided in the middle of the negative pressure conduit 9. The negative pressure pump 16 has a connecting pipe portion 23 shown in FIG.
Is connected to the connection pipe 4A of the shell 4 via the other side pipe 9B.

Reference numeral 17 denotes a pump housing of the negative pressure pump 16. The pump housing 17 has a bottomed cylindrical isolation chamber housing 18 formed with a large-diameter cylinder 18A, as shown in FIGS. The partition wall 19 is provided so as to cover the large-diameter cylinder 18A of the housing 18 from the opening end side.
And a closed cylindrical working chamber housing 20 fixed to the isolated chamber housing 18 through the working chamber housing 2.
Reference numeral 0 also serves as a casing of the check valve 15. And
In the working chamber housing 20, a small-diameter cylinder 20A and a sliding hole 20B into which a relief plunger 48 described later is inserted are formed as bottomed holes.

Reference numeral 21 denotes a connecting pipe provided in the working chamber housing 20. The connecting pipe 21 is connected to one side pipe 9A of the negative pressure conduit 9 between the intake manifold 10 and the check valve 15 of the engine. ing. Reference numeral 22 denotes a negative pressure introduction passage formed in the working chamber housing 20 and the partition wall 19 so as to communicate with the connection pipe portion 21. The negative pressure introduction passage 22 always communicates with a negative pressure chamber C described later, and the intake manifold 10 Negative pressure from the negative pressure chamber C
Lead to.

Reference numeral 23 denotes another connection pipe provided in the working chamber housing 20. The connection pipe 23 is provided on the other side pipe 9 of the negative pressure conduit 9.
It is connected to the connection pipe section 4A of the shell 4 via B, and supplies a vacuum pressure from a pump chamber G described later to the negative pressure chamber A in the shell 4. It should be noted that in FIG.
Although the check valve 15 is provided in the working chamber housing 20 between the positions 1 and 23, the check valve 15 is not necessarily provided in the working chamber housing 20. Needless to say, the check valve 15 may be provided outside the unit 20.

Reference numeral 24 denotes an isolation piston as a large-diameter piston slidably inserted into the large-diameter cylinder 18A of the isolation chamber housing 18. The isolation piston 24 serves as a first pressure chamber in the large-diameter cylinder 18A. , And a back pressure chamber D as a second pressure chamber. An annular projection 24A is provided on the outer peripheral side of the isolation piston 24 toward the negative pressure chamber C by a certain dimension.
A comes into contact with the outer peripheral portion of the partition wall 19 when the isolation piston 24 is greatly slid toward the negative pressure chamber C, and regulates the stroke end of the isolation piston 24.

The isolation piston 24 has small-diameter rods 24B, 24B extending from the center thereof toward both sides in the axial direction.
C is integrally provided, and the distal end of the rod 24B is
And is connected to a working piston 43 described later.
On the other hand, the rod 24C of the isolation piston 24 projects outward from the bottom side of the isolation chamber housing 18, and a disc-shaped spring receiver 25 is fixed to the projected end side. In addition, a recess 18B for a spring receiver is formed on the bottom side of the isolated chamber housing 18 at a position facing the spring receiver 25 in the axial direction.

26 is a concave portion 18B of the isolated chamber housing 18.
The spring 26 constantly urges the isolation piston 24 from the negative pressure chamber C side to the back pressure chamber D side. When the pressure state between C and D is substantially equal, the isolation piston 24 is slid and displaced from the negative pressure chamber C side to the back pressure chamber D side. When the negative pressure from the negative pressure introduction passage 22 causes the negative pressure chamber C to be lower in pressure than the back pressure chamber D, the differential pressure at this time causes the isolation piston 24 to move from the back pressure chamber D side to the negative pressure chamber C side. The spring load of the spring 26 is set so as to allow sliding displacement toward.

Reference numeral 27 denotes a switching plate located radially outside the spring 26 and provided on the bottom side of the isolation chamber housing 18. The switching plate 27 is formed as a stepped annular plate from a thin metal plate or the like. The outer peripheral side of the isolated chamber housing 18 is connected to each pivot 28 via each weak spring 29.
, For example, is mounted at a three-point support state. The switching plate 27 is constantly urged in the direction of arrow E1 in FIG. 3 by each weak spring 29, and is held at the position shown by each pivot 28.

Here, the isolation piston 24 is connected to the spring 2
When the spring receiver 25 slides toward the negative pressure chamber C side to the stroke end against the rod 6 and the spring receiver 25 is greatly displaced together with the rod 24C in the direction indicated by the arrow E2 in FIG. By contact, switching plate 2
Numeral 7 is displaced in the direction of arrow E2 against each weak spring 29, and at the same time, pushes an atmosphere switching valve 31 described later in the direction of arrow E2 to switch the atmosphere switching valve 31 from the open position to the closed position.

Numeral 30 denotes a spring support 25 and a spring 26
The cover 30 is formed as a truncated cone-shaped cap body from a metal plate or the like so as to cover the isolation chamber 24 from outside. It is configured to protect the rod 24C, the spring receiver 25, the spring 26, the switching plate 27, and the like.

Reference numeral 31 denotes an atmosphere switching valve as a first switching valve mechanism provided on the bottom side of the isolated chamber housing 18,
As shown in FIG. 3, the atmosphere switching valve 31 has a disc spring 33 attached on the outer peripheral side to the bottom side of the isolated chamber housing 18 by a stopper 32 and a base end provided on the inner peripheral side of the disc spring 33 via a cap 34. A guide valve body 35 which is mounted and whose distal end projects into the back pressure chamber D in the isolation chamber housing 18.
And an annular seat 36 which is fitted on the outer peripheral side of the intermediate portion of the guide valve body 35 and hermetically seals the back pressure chamber D against the outside atmosphere.

Here, when the isolation piston 24 is largely slid to the back pressure chamber D side to the stroke end as shown in FIGS.
5 is pressed by the isolation piston 24 in the direction of arrow E1 to open the valve as shown in the drawing, and the back pressure chamber D of the isolation chamber housing 18 is communicated with the atmosphere, and the atmosphere is introduced into the back pressure chamber D. To allow And the atmosphere switching valve 31
Thereafter, the guide valve element 35 is held at the valve-opening position shown in the figure by the disc spring 33 until the cap 34 is pressed in the direction of the arrow E2, and the inside of the back pressure chamber D is kept at atmospheric pressure.

On the other hand, the isolation piston 24 is
When the sliding displacement to the negative pressure chamber C side to the stroke end is performed against the pressure, the cap 34 of the atmosphere switching valve 31 is pressed by the switching plate 27 in the direction indicated by the arrow E2 as described above, whereby the atmosphere switching valve 31 is pressed. The disc spring 33 is inverted from the position shown in the figure, and the annular seat 36 is connected to the guide valve body 3.
5, the valve is switched from the valve-opening position to the valve-closing position. At this time, the annular seat 36 shuts off the back pressure chamber D from the outside, so that the atmosphere switching valve 31 keeps its closed position until the guide valve element 35 is pressed in the direction of arrow E1. Things.

Numeral 37 denotes a negative pressure switching valve as a second switching valve mechanism provided on the isolation piston 24. The negative pressure switching valve 37 is attached to the isolation piston 24 by a stopper 38 on the outer peripheral side as shown in FIG. A disc spring 39, a guide valve body 41 whose base end is attached to the inner peripheral side of the disc spring 39 via a cap 40, and whose distal end projects into the negative pressure chamber C in the isolated chamber housing 18. An annular seat 42 is fitted on the outer peripheral side of the intermediate portion of the valve element 41 and hermetically seals the negative pressure chamber C against the back pressure chamber D.

Here, when the isolation piston 24 is greatly slid and displaced to the stroke end on the back pressure chamber D side as shown in FIGS. 2 and 3, the negative pressure switching valve 37 causes the cap 40 to move to the bottom of the isolation chamber housing 18. As a result, the disc spring 39 is inverted as shown in the drawing, and the annular seat 42 is urged in the direction of arrow F1 via the guide valve body 41 by contact with the side. The valve is switched from the open position to the closed position. At this time, the annular sheet 4
2 shuts off between the negative pressure chamber C and the back pressure chamber D,
Next, until the guide valve element 41 is pressed in the direction indicated by the arrow F2, the negative pressure switching valve 37 holds the valve closing position by itself.

On the other hand, the isolation piston 24 is
When the negative pressure switching valve 37 is slid to the stroke end on the negative pressure chamber C side, the distal end side of the guide valve body 41 of the negative pressure switching valve 37 abuts on a relief plunger 48 described later, and FIG.
The disc spring 39 is inverted from the position shown in the figure by being pressed in the direction of arrow F2. Thereby, the annular sheet 42
Is urged in the direction of arrow F2 through the guide valve body 41, and the negative pressure switching valve 37 is switched from the closed position to the open position.
Then, the negative pressure switching valve 37 is thereafter connected to the cap 40.
Until is pressed in the direction of arrow F1, the disc spring 39 holds the guide valve body 41 in the valve open position, and the negative pressure chamber C and the back pressure chamber D
And keep in communication.

Reference numeral 43 denotes a working piston as a small-diameter piston slidably fitted in the small-diameter cylinder 20A of the working chamber housing 20, and the working piston 43 is a pump inside the small-diameter cylinder 20A as shown in FIGS. A chamber G and an atmosphere chamber H are defined, and the atmosphere chamber H is always in communication with the outside atmosphere through an atmosphere communication passage 44 formed between the partition wall 19 and the working chamber housing 20. The working piston 43 is connected to the distal end of the rod 24B of the isolation piston 24, and reciprocates in the small-diameter cylinder 20A following the isolation piston 24.

A check valve 45 is provided on the outer peripheral side of the working piston 43 as a negative pressure compensating valve. The check valve 45 is mounted on the outer peripheral side of the working piston 43 as shown in FIG. And an annular lip seal that comes into sliding contact with the lip seal. The check valve 45 allows the air in the pump chamber G to be discharged toward the atmosphere chamber H when the working piston 43 reciprocates in the small-diameter cylinder 20A, and prevents the flow in the opposite direction. It is.

46 is a negative pressure passage formed in the working chamber housing 20 and located between the connection pipe section 23 and the pump chamber G.
47 is a check valve as a negative pressure supply valve provided in the middle of the negative pressure passage 46. The check valve 47 allows air to be sucked from the connection pipe portion 23 toward the pump chamber G, It is configured to block the flow in the reverse direction. And the working piston 4
3 is slidably displaced in the small-diameter cylinder 20A toward the pump chamber G side, and when the pressure in the pump chamber G rises, the check valve 47 is closed and the air in the pump chamber G is connected to the connection pipe portion 23. And the check valve 45 is opened to discharge the air in the pump chamber G to the atmosphere chamber H side.

The working piston 43 is mounted on the small-diameter cylinder 2.
When the pressure in the pump chamber G is reduced by sliding displacement of the inside of the pump chamber G toward the atmosphere chamber H, the check 45 is closed to prevent the air from flowing from the atmosphere chamber H into the pump chamber G. At the same time, when the pressure in the pump chamber G becomes lower than the pressure on the connection pipe section 23 side, the check valve 47 opens and the negative pressure chamber A in the shell 4 shown in FIG. The air is sucked into the pump chamber G through the like. As a result, a vacuum pressure lower than the negative pressure from the intake manifold 10 is supplied to the negative pressure chamber A in the shell 4 from the pump chamber G of the negative pressure pump 16 via the connection pipe parts 23, 9B and the like. Is done.

Reference numeral 48 denotes a sliding hole 20 of the working chamber housing 20.
A relief plunger slidably inserted in B,
One end of the relief plunger 48 has a rod portion 48A.
As a result, the protrusion protrudes into the negative pressure chamber C, and the other end side is a stopper portion 48B that can contact the bottom side of the sliding hole 20B. The relief plunger 48 includes a vacuum pressure setting spring 49 on the outer peripheral side of the stopper portion 48B.
When the pressure on the sixth side falls below the atmospheric pressure by the set pressure of the spring 49, the differential pressure (vacuum pressure) at this time causes the vacuum pressure setting spring 49 to bend and deform, and the relief plunger 48 is moved by the stopper portion 48B. It is slid and displaced to a position where it comes into contact with the bottom side of the sliding hole 20B.

As a result, the relieving plunger 48 moves backward when the distal end of the rod portion 48A retreats toward the partition wall 19 in the direction of arrow F1 and the isolation piston 24 slides to the stroke end on the negative pressure chamber C side. The guide valve element 41 of the negative pressure switching valve 37 does not contact the distal end side of the rod portion 48A and is not pressed in the direction of arrow F2, and the negative pressure switching valve 37 remains closed. In this case, the isolation piston 24 stops at the stroke end position, and the operation piston 43 also stops moving at the stroke end on the pump chamber G side. No lower vacuum pressures will occur.

Reference numeral 50 denotes a check valve disposed between the rod 24B of the isolation piston 24 and the partition wall 19. As shown in FIG. 4, the check valve 50 is an annular lip seal that slides on the outer peripheral surface of the rod 24B. And so on. The check valve 50 allows the air in the negative pressure chamber C to be discharged toward the atmosphere chamber H when the isolation piston 24 slides toward the negative pressure chamber C, and prevents the flow in the opposite direction. Is what you do.

A bypass passage 51 bypasses the pump chamber G and connects the valve seat side of the check valve 15 to the sliding hole 20B. The bypass passage 51 connects the connection pipe 21 to the check valve 15.
Through the sliding hole 20B, the negative pressure passage 46 and the connecting pipe 2
The check valve 15 is opened and closed by a differential pressure between the connection pipe portions 21 and 23, for example. In this case, the check valve 15 closes when the pressure on the connection pipe 21 is higher than the pressure on the connection pipe 23, but opens when the pressure on the connection pipe 23 is higher than the pressure on the connection pipe 21. Is what you do.

The negative pressure booster according to the present embodiment has the above-described configuration, and its operation will now be described.

First, as shown in FIG. 2, when the isolation piston 24 is slid to the stroke end in the large-diameter cylinder 18A of the isolation chamber housing 18 toward the back pressure chamber D, the atmosphere switching valve 31 is opened. And the back pressure chamber D is communicated with the outside atmosphere, the negative pressure switching valve 37 is closed, and the negative pressure chamber C is closed.
And the back pressure chamber D is shut off. Then, since the negative pressure from the intake manifold 10 is supplied to the negative pressure chamber C through the negative pressure introduction passage 22, the inside of the negative pressure chamber C is in a negative pressure state. Also,
Atmospheric pressure is introduced into the back pressure chamber D via an atmosphere switching valve 31.

As a result, a differential pressure is generated between the negative pressure chamber C and the back pressure chamber D, and the isolation piston 24 moves the spring from the back pressure chamber D side to the negative pressure chamber C side by the differential pressure at this time. The sliding displacement is made against the sliding motion 26. When the isolation piston 24 is largely displaced by sliding toward the negative pressure chamber C, the annular projection 2
4A abuts on the outer peripheral portion of the partition wall 19 to regulate the stroke end of the isolation piston 24, and the guide valve body 41 of the negative pressure switching valve 37 abuts on the rod portion 48A of the relief plunger 48, thereby switching the negative pressure. Valve 37
Is pressed in the direction of arrow F1 to switch from the valve closing position to the valve opening position.

At this time, the isolation piston 24 is slid toward the negative pressure chamber C to the stroke end, and the spring receiver 25 is greatly displaced together with the rod 24C against the spring 26 in the direction of arrow E2 in FIG. Therefore, the spring receiver 25 abuts on the switching plate 27 in a state where the spring 26 is largely bent, and the switching plate 27
The cap 34 of the atmosphere switching valve 31 is indicated by an arrow E against
By pressing in two directions, the atmosphere switching valve 31 switches from the valve opening position to the valve closing position, and shuts off the back pressure chamber D from the outside atmosphere.

Thus, the isolation piston 24 is connected to the negative pressure chamber C.
When the sliding displacement reaches the stroke end on the side, the atmosphere switching valve 31 is switched to the closed state to shut off the back pressure chamber D from the outside atmosphere, and the negative pressure switching valve 37 is opened. By switching, the communication between the negative pressure chamber C and the back pressure chamber D is established, so that the negative pressure chamber C and the back pressure chamber D are in the same pressure state. From the side to the back pressure chamber D side.

Then, when the isolation piston 24 slides and displaces to the stroke end on the back pressure chamber D side as shown in FIG.
The atmosphere switching valve 31 is pressed by the isolation piston 24 to switch to the valve-opening position, thereby connecting the back pressure chamber D to the outside atmosphere, and connecting the negative pressure switching valve 37 to the isolation chamber housing 1.
8 and is switched to the valve-closed position by contacting the bottom side of 8 to shut off the negative pressure chamber C from the back pressure chamber D. Thus, the isolation piston 24 is slid and displaced from the back pressure chamber D side to the negative pressure chamber C side again against the spring 26 due to the differential pressure between the negative pressure chamber C and the back pressure chamber D. .

Thus, the isolation piston 24 repeats the reciprocating motion in the large-diameter cylinder 18A of the isolation chamber housing 18 due to the differential pressure between the negative pressure from the intake manifold 10 and the atmospheric pressure or the like. The small-diameter cylinder 2 of the working chamber housing 20 follows the piston 24
The reciprocating motion is repeated within 0A, and the operating piston 43
Can be generated in the pump chamber G when the sliding displacement from the pump chamber G toward the atmosphere chamber H is lower than the negative pressure from the intake manifold 10.

In this case, the isolation piston 24 has, for example, about 3 to 5 times the outer diameter of the working piston 43, and the isolation piston 24 that slides in the large-diameter cylinder 18A is in the small-diameter cylinder 20A. Has a pressure receiving area about 9 to 25 times that of the working piston 43, the working piston 43 can be driven by the separation piston 24 with a force proportional to the pressure receiving area of both, and the working piston 43 is made to follow the separation piston 24. Can be reliably reciprocated in the small-diameter cylinder 20A.

Thus, when the working piston 43 slides and displaces from the pump chamber G toward the atmosphere chamber H, a vacuum pressure lower than the negative pressure from the intake manifold 10 is reliably generated in the pump chamber G. When the pressure in the pump chamber G becomes lower than the vacuum pressure in the negative pressure chamber A in the shell 4, the check valve 47 for supplying vacuum pressure opens to connect the pump pipe G to the connection pipe. A vacuum pressure can be supplied to the negative pressure chamber A in the shell 4 via the parts 23, 9B and the like.

When the working piston 43 is slid and displaced from the atmosphere chamber H toward the pump chamber G, the pump chamber G
Even if the pressure in the pump chamber G rises to the atmospheric pressure level, the air in the pump chamber G can be discharged to the atmosphere chamber H side by the check valve 45 at this time, so that the pressure in the pump chamber G rises to the atmospheric pressure or more. This can be prevented by the check valve 45, and the pump chamber G can be constantly maintained at a pressure state equal to or lower than the atmospheric pressure.

Therefore, according to this embodiment, the negative pressure generated in the intake manifold 10 of the engine is
4 can be reliably reduced to a vacuum pressure lower than, for example, 500 mmHg. By supplying this vacuum pressure to the negative pressure chamber A in the shell 4, when the brake pedal 1 is depressed, Booster unit 3
A very large differential pressure can be generated between the negative pressure chamber A and the control pressure chamber B in the shell 4 of FIG. Then, at the time of the brake operation, a large operating force obtained by boosting the pedal depressing force can be transmitted from the output shaft 8 to the master cylinder 11 by utilizing the pressure difference between the negative pressure chamber A and the control pressure chamber B.

The negative pressure pump 16 has a structure in which the intake manifold 10 of the engine is provided in the middle of the negative pressure conduit 9 connected to the negative pressure chamber A of the shell 4 via the check valve 15 and the like. As shown, the booster device main body 3 including the shell 4 and the diaphragm 5 can be used as it is, and it is possible to reliably prevent the entire device from being enlarged.

Further, since the negative pressure from the intake manifold 10 is used as a driving source of the negative pressure pump 16, the size of the driving device is significantly smaller than that in the case where a vehicle engine is used as a driving source for a vacuum pump. It is possible to reduce the size and weight of the engine, to reduce the mounting space on the engine room side, and to surely reduce the manufacturing cost and the assembly cost.

On the other hand, a relief plunger 48 provided with a vacuum pressure setting spring 49 is provided in the pump housing 17 of the negative pressure pump 16. For example, when the vacuum pressure in the negative pressure chamber A side is excessively reduced, the vacuum is set. Since the pressure setting spring 49 is flexed and deformed to retract the rod portion 48A of the relief plunger 48 toward the partition wall 19, the negative pressure switching valve 37 is maintained in the closed state. Can be stopped together with the operating piston 43 at the position, the vacuum pressure on the negative pressure chamber A (connection pipe portion 23) side can be reliably prevented from excessively dropping, and the relief plunger 48 and the like are compactly housed in the pump housing 17. This has the effect of being able to be accommodated in

In the above embodiment, the check valve 15 is provided in the working chamber housing 20 between the connecting pipe portions 21 and 23 as illustrated in FIG. 2, but the present invention is not limited thereto. Not limited to, for example, separate from the pump housing 17,
The check valve 15 may be provided outside the working chamber housing 20.

In the above embodiment, the case where the output shaft 8 of the booster body 3 is connected to the master cylinder 11 for braking has been described as an example. However, the present invention is not limited to this. The present invention may be applied to other cylinder devices such as a master cylinder for a clutch.

[0066]

As described in detail above, according to the first aspect of the present invention, a negative pressure type having a partition member and a control valve mechanism for defining a negative pressure chamber and a control pressure chamber in a shell. A booster means, and a negative pressure conduit connected to the shell so as to guide a negative pressure generated in an intake manifold of the engine into the negative pressure chamber. In the middle of the negative pressure conduit, a negative pressure from the intake manifold is provided. A negative pressure pump means for generating a negative pressure even lower than the pressure in the negative pressure chamber, and a check valve for allowing air to flow from the negative pressure chamber side toward the intake manifold side and preventing a reverse flow. Since the negative pressure is further reduced by the negative pressure pump means than the negative pressure from the intake manifold, the differential pressure between the negative pressure chamber and the control pressure chamber can be reliably increased. Can take more force from the output shaft by the pressure difference It is, it can hold a negative pressure pump means and the vacuum chamber by the check valve to a lower pressure (negative pressure) state than the intake manifold side. Therefore, the output of the pneumatic booster can be reliably improved without increasing the size of the whole, and a large operating force can be transmitted to the master cylinder and the like, and the mounting space and the like can be reduced, and the cost can be reduced. It becomes possible to plan.

According to the present invention, of the large-diameter cylinder and the small-diameter cylinder provided in the pump housing of the negative-pressure pump means, the large-diameter cylinder has a negative pressure from the intake manifold and an external pressure. A large-diameter piston that repeats reciprocating motion by a differential pressure from the atmospheric pressure is provided, and reciprocates in the small-diameter cylinder following the large-diameter piston to define a pump chamber and an atmosphere chamber in the small-diameter cylinder. A small-diameter piston is provided, a negative pressure compensating valve for allowing air in the pump chamber to be discharged toward the atmosphere chamber and preventing a reverse flow, and a valve which is normally closed to allow the shell inside the pump chamber. And a negative pressure supply valve that disconnects the pump chamber from the negative pressure chamber when the pressure in the pump chamber becomes lower than the negative pressure chamber in the shell. The small diameter pi A pressure (negative pressure) lower than the negative pressure from the intake manifold can be generated in the pump chamber when the valve slides from the pump chamber toward the atmosphere chamber side following the large-diameter piston, This negative pressure can be supplied from the pump chamber to the negative pressure chamber in the shell via the negative pressure supply valve. Further, when the small-diameter piston slides from the atmospheric chamber toward the pump chamber, even if the pressure in the pump chamber rises to the atmospheric pressure level, the air in the pump chamber is released by the negative pressure compensating valve at this time. The pump chamber can always be kept at a pressure equal to or lower than the atmospheric pressure.

On the other hand, according to the third aspect of the present invention, when the large-diameter piston is slid to the stroke end in the large-diameter cylinder toward the second pressure chamber, the first switching valve mechanism allows the first switching valve mechanism to move the piston. Since the second pressure chamber is communicated with the outside atmosphere and the first and second pressure chambers are shut off by the second switching valve mechanism, the first pressure chamber is filled with the negative pressure from the negative pressure introduction passage. The second pressure chamber can be set to the atmospheric pressure in a negative pressure state, and the large-diameter piston is moved from the second pressure chamber side to the first pressure by a differential pressure generated between the first and second pressure chambers. The sliding displacement can be performed against the urging means toward the chamber side. Also,
When the large-diameter piston slides in the large-diameter cylinder toward the first pressure chamber toward the stroke end, the first switching valve mechanism switches to the closed state, thereby closing the second pressure chamber. The outside air is shut off, and the second switching valve mechanism is switched to the open state to communicate between the first and second pressure chambers. The large-diameter piston can be slid from the first pressure chamber toward the second pressure chamber by the urging force of the urging means.

When the small-diameter piston slides from the pump chamber toward the atmosphere chamber following the large-diameter piston in the same manner as in the second aspect of the present invention, the negative pressure is more than the negative pressure from the intake manifold. A low pressure (negative pressure) is generated in the pump chamber, and this negative pressure can be supplied from the pump chamber to the negative pressure chamber in the shell via the negative pressure supply valve, so that the output of the pneumatic booster is reliably improved. In addition, a large operating force can be transmitted to the master cylinder and the like, and the whole can be reduced in size and weight to reduce the mounting space and the like, and the manufacturing cost and the assembly cost can be reliably reduced.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram showing a pneumatic booster according to an embodiment of the present invention.

FIG. 2 is an enlarged longitudinal sectional view showing a negative pressure pump device in FIG. 1;

FIG. 3 is an enlarged vertical sectional view of an atmosphere switching valve, a negative pressure switching valve, and the like in a left half of FIG. 2;

4 is a longitudinal sectional view of a working piston, a relief plunger, and the like, showing a right half in FIG. 2 in an enlarged manner.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Brake pedal 2 Negative pressure booster 3 Booster main body (power booster) 4 Shell 5 Diaphragm (partition member) 6 Input shaft 7 Control valve mechanism 8 Output shaft 9 Negative pressure conduit 10 Intake manifold 11 Master cylinder 14 Negative pressure Pump device 15 Check valve 16 Negative pressure pump (Negative pressure pump means) 17 Pump housing 18 Isolation chamber housing 18A Large diameter cylinder 19 Partition wall 20 Working chamber housing 20A Small diameter cylinder 22 Negative pressure introduction path 24 Isolation piston (large diameter piston) 26 Spring (biasing means) 31 Atmospheric switching valve (first switching valve mechanism) 37 Negative pressure switching valve (second switching valve mechanism) 43 Working piston (small diameter piston) 44 Atmospheric communication path 45 Check valve (Negative pressure compensating valve) ) 47 Check valve (negative pressure supply valve) 48 Plunger for relief A Negative pressure chamber B Control pressure chamber C Pressure chamber (first pressure chamber) D back pressure chamber (second pressure chamber) G pump chamber H atmospheric chamber

Claims (3)

[Claims] A partition member provided in the shell and defining a negative pressure chamber and a control pressure chamber inside the shell; and the negative pressure provided in the partition member in response to a pressing operation of an input shaft. A control valve mechanism for communicating and shutting off between the pressure chamber and the control pressure chamber, and an output for boosting the pressing force of the input shaft by a differential pressure between the negative pressure chamber and the control pressure chamber and outputting the same to the outside. A negative pressure type booster comprising a shaft; a negative pressure conduit connected to the shell so as to guide a negative pressure generated in an intake manifold of the engine into a negative pressure chamber of the booster; Negative pressure pump means provided on the way to generate a negative pressure in the negative pressure chamber lower than the negative pressure from the intake manifold to increase the differential pressure between the negative pressure chamber and the control pressure chamber. , Provided in the middle of the negative pressure conduit, from the negative pressure chamber side to the intake manifold side. And a check valve for preventing air from flowing in the opposite direction. 2. A pump housing having a large-diameter cylinder and a small-diameter cylinder, a negative-pressure pump means slidably provided in the large-diameter cylinder of the pump housing, and a negative pressure from the intake manifold and a large external pressure. A large-diameter piston that repeats reciprocating motion in the large-diameter cylinder by a pressure difference from the atmospheric pressure, and reciprocates in a small-diameter cylinder of the pump housing following the large-diameter piston, and a pump chamber and an air chamber A negative pressure compensating valve that allows air in the pump chamber to be discharged toward the atmosphere chamber and prevents a reverse flow, and a valve that is normally closed to close the pump chamber. From the negative pressure chamber in the shell, and a negative pressure supply valve for communicating the pump chamber with the negative pressure chamber when the pressure in the pump chamber becomes lower than the negative pressure chamber in the shell. Make up The vacuum booster according to claim 1, wherein 3. A pump housing having a large-diameter cylinder and a small-diameter cylinder, the negative-pressure pump means being slidably provided in a large-diameter cylinder of the pump housing, and a first pressure in the large-diameter cylinder. A large-diameter piston defined in a chamber and a second pressure chamber; a negative-pressure introduction passage formed in the pump housing for introducing a negative pressure from the intake manifold into the first pressure chamber; From the first pressure chamber side to the second pressure chamber side, and when the first pressure chamber becomes lower in pressure than the second pressure chamber due to the negative pressure from the negative pressure introduction path, Urging means for allowing the large-diameter piston to slide and displace from the second pressure chamber side to the first pressure chamber side due to the differential pressure at this time; and Sliding toward stroke end toward 1 pressure chamber side When the second pressure chamber is closed, the second pressure chamber is shut off from the outside atmosphere, and when the large-diameter piston slides in the large-diameter cylinder toward the second pressure chamber to the stroke end, the second pressure chamber is closed. 2
A first switching valve mechanism for communicating the pressure chamber with the atmosphere, and the first pressure when the large-diameter piston is slid to the stroke end in the large-diameter cylinder toward the first pressure chamber. The chamber is communicated with a second pressure chamber, and when the large-diameter piston slides in the large-diameter cylinder toward the second pressure chamber to the stroke end, the first pressure chamber is brought into the second pressure chamber. A second switching valve mechanism that shuts off the chamber, and slides and displaces in a small-diameter cylinder of the pump housing following the large-diameter piston to define a pump chamber and an atmosphere chamber in the small-diameter cylinder. A small-diameter piston, a negative pressure compensating valve for allowing air in the pump chamber to be discharged toward the atmosphere chamber and preventing a reverse flow, Shut off from the negative pressure chamber and 2. A negative pressure supply valve for connecting the pump chamber to the negative pressure chamber when the force becomes lower than the negative pressure chamber in the shell.
A negative pressure booster according to any one of the above.