JPS6025839A - Pneumatic booster - Google Patents

Abstract

PURPOSE:To make the servo ratio changeable manually or automatically and at the same time enhance the structural strength of the titled device by a structure wherein two pistons are independently arranged in tandem in a shell so as to make change-over pressure chambers formed by being partitioned with said pistons in the shell at will. CONSTITUTION:A first piston 5 and a second piston 6 are independently arranged in a shell so as to partition independent chambers B and C respectively at the back of the first piston 5 and the back of the second piston 6. Pressure lead-in ports 24, 25 and 26 are respectively provided on a first constant pressure chamber A, the first working pressure chamber B and a second working pressure chamber D and connected to a change-over valve 27 installed outside the shell. Either one state to communicate the working chamber B with the constant pressure chamber A or the other state to communicate the working chamber B with the working pressure chamber D can be selected at will by means of the change-over valve 27.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a pressure booster used in brake devices, clutch devices, etc. of vehicles, and more specifically, a pressure booster device in which a plurality of pistons are arranged in series in a shell. This invention relates to a tandem pressure booster.

(Prior Art) A conventional tandem type pressure booster had a general structure as shown in FIG. That is, a first diaphragm 3 and a second diaphragm 4 are stretched in a closed container (shell) composed of a front shell 1 and a rear shell 2, and both diaphragms 3 and 4 have a first diaphragm 3 and a second diaphragm 4, respectively. A piston 5 and a second piston 6 are attached. and,
The two pistons 5.6 are connected by the cylindrical member 7, and the first piston 5 is connected between the two pistons 5.6.
A center grate (partition wall) 8 defining a side trap chamber is provided, and the cylindrical member 7 can slide against the center plate 8 in an airtight manner.

Thus, at the front and rear of the first and second pistons 5 and 6,
Four pressure chambers A, B, C, and D are defined, and among these, pressure chambers A and C serve as first and second constant pressure chambers and communicate with each other through an internal passage 9. 11 to the negative pressure generating section of the vehicle engine, while the pressure chamber B
and D communicate with each other through a passage 11 of the second diaphragm 4 as first and second foot dynamic pressure chambers.

A driven rod 12 is inserted into the shaft of the cylindrical member 7 from the side of the first piston 5 and has a seven-rank portion 13 at its rear end, the tip of which is connected to a mask cylinder (not shown). The flange portion 13 is fitted into a storage body 14 fixed to the second piston 6. Reference numeral 15 denotes an operating rod that is linked to a pedal (not shown) and is engaged with the storage body 14 via a valve plunger 16. A well-known valve mechanism 17 including the valve plunger 16 serves to interrupt communication between the second constant pressure chamber C and the second operating pressure chamber in response to the displacement of the second screw.

Note that 18 is an elastic pressure deformation member interposed between the flange portion 13 of the driven rod 12 and the plunger 16;
It becomes an intermediate part that transmits reaction force. Further, the first and second pistons 5.6 are urged to the return position by a return spring 19 interposed in front of the first piston 5.

With this configuration, when no pedal force is applied to the pedal and the operating rod 12 is not displaced, the valve mechanism 17 connects the second constant pressure chamber C and the second operating pressure chamber 1), so that the pressure chamber A ,
B, C, and D are all kept at the same pressure, and the first and second pistons 5.6 are not displaced.

On the other hand, when the operating rod 15 is displaced to the left in the figure, the valve mechanism 17 cuts off the communication between the second constant pressure chamber C and the second working pressure chamber, and also closes the second working pressure chamber. Introduce the atmosphere into the As mentioned above, since the first and second constant pressure chambers A and C and the first and second working pressure chambers B and D are in communication with each other, the operation of the valve mechanism 17 prevents the introduction of atmospheric air. The first and second working pressure chambers B, D and the first chamber are connected to a negative pressure source.
, and the second constant pressure chambers A and C, and this pressure difference causes the first and second pistons 5.6 to be displaced. As a result, the driven rod 12 receiving the thrust of the first and second pistons 5.6 actuates the mask cylinder. At this time, the force is transmitted to the operating rod 15 via the anti-cover sliding rod 12, the pressurizing deformation member 18, and the valve plunger 16.

The input/output characteristics of the air pressure booster having the above configuration are as shown in FIG. 2.

In other words, there is an initial characteristic (A) in which the output Fθ jumps in when the input Fi is constant, a medium-term characteristic (11) in which the output Fθ increases with a predetermined slope, tanθ, with respect to the input Fi, and an increase in the output Fθ is moderated. The three l with the terminal characteristic (C) to be
It has ij characteristics. Here, the initial characteristic (A) occurs before the reaction force is transmitted to the operating rod 15, and specifically, the initial characteristic (A) is the one that occurs before the reaction force is transmitted to the operating rod 15. represents the output. In addition, the medium-term characteristic (IJ) occurs while the reaction force is being transmitted to the operating rod via the valve plunger 18, and its output Fθ
The input FiO ratio, that is, tanθ, becomes the so-called servo ratio. Specifically, if the outer diameter iDx of the flange portion 13 of the driven rod 12 and the outer diameter iD2 of the tip of the valve plunger 16 are:
It is expressed as (D1/D2)2.

However, as mentioned above, the servo ratio is uniquely determined by only the outer diameter D1 of the flange portion 13 of the driven rod 12 and the outer diameter D2 of the tip end of the valve plunger 16. Therefore, if you want to increase the servo ratio, The servo ratio cannot be set above a certain value due to dimensions, and even if one wishes to arbitrarily select the servo ratio during use, it is impossible to change the servo ratio. In addition, there is no other way to change the jump-in characteristics other than changing the value of δ, and furthermore, since the first and second pistons are integrally connected, the design has sufficient strength. Generally speaking, conventional air pressure boosters have been limited in that they require extensive design changes depending on the application, that is, the conditions of use.

(Object of the Invention) In view of the above-mentioned problems of the prior art, the present invention is capable of greatly increasing the servo ratio, allowing arbitrary selection of the servo ratio, and easily changing the jump-in characteristic. The purpose of the present invention is to provide an air pressure booster that can be used as a whole and has a design margin as a whole.

(Structure of the Invention) This object is to provide a first driven rod that protrudes outside the shell on a first piston located at the front, and to provide a first driven rod that protrudes outside the shell on a first piston located at the front, and to attach the first driven rod to a second piston located at the rear. A second driven rod is provided whose tip abuts the driven rod, an operating rod is connected to the rear end of the second driven rod via a reaction force mechanism, and a first working pressure chamber and a first working pressure chamber are connected to each other. Either the first working pressure chamber and the second working pressure chamber are in communication with the constant pressure window.
A valve mechanism that allows you to select either state in communication with the operating pressure chamber? This is achieved by means of a pressure booster provided.

(Example) Hereinafter, an example of the present invention will be described based on the accompanying drawings.

FIG. 3 shows the structure of a pressure booster according to the present invention. Note that the same components as those shown in FIG. 1 are denoted by the same reference numerals, and explanations of their functions will be omitted. In this embodiment, a cylindrical member 21 that can slide on the center plate 8 in an airtight manner is fixed only to the first piston 5. On the other hand, the driven rod that transmits the thrust is a first driven rod 22 fixed to the first piston 5 and a second driven rod whose flange portion 23a is fitted into the storage body 14 of the second piston 6.
The tip of the second driven rod 23 is brought into contact with a recess 22a provided at the rear end of the first driven rod 22. In addition, the first and second
The passage 11 (FIG. 1) that completely communicates with the working pressure chambers B and D has been eliminated.

That is, in the air pressure booster according to the present invention, the first piston 5 and the second piston 6 are arranged independently in the shell, and the rear part of the first piston 5 and the second piston 6 are arranged separately. At the rear, independent chambers H and C2 are defined.

However, the first constant pressure iA and the first working pressure chamber J3,
The second working pressure chamber is provided with first, second, and third pressure inlets 24, 25, and 26, respectively, and is connected to an external switching valve 27. The switching valve 27 has a first constant pressure chamber A,
The structure allows you to arbitrarily select either a state where the first working pressure chamber B and the second working pressure chamber B are in communication, or a state where the first working pressure chamber B and the second working pressure chamber B are connected to each other. There is.

With this configuration, the switching valve 27 is now connected to the first constant pressure chamber A.
When communicating with the first working pressure chamber B, first,
When no pedal force is applied to the beggle and the operating rod 15 is not displaced from 1 to 1, the valve mechanism 17 connects the second constant pressure chamber C and the second operating pressure chamber, so that the pressure chambers A, B, and C are connected to each other. , D are all kept at the same pressure, and the first and second pistons 5.6 are not displaced.

On the other hand, when the operating rod 15 is displaced to the left in the figure, the valve mechanism 17 cuts off the communication between the second constant pressure chamber C and the second working pressure chamber, and Introduce atmosphere, ie pressure chamber A.

Since the atmosphere is introduced only into the second working pressure chamber among B, C, and D, a pressure difference occurs between the second constant pressure chamber C and the second working pressure chamber, and this pressure difference As a result of the displacement of the second piston 6, the first driven rod 22 receives the thrust of the second piston 6 via the second driven rod 23, thereby operating the mask cylinder. At this time, the reaction force is applied to the first and second driven rods 22, 23, the pressurizing deformation member 18, and the valve plunger 16.
The signal is transmitted to the operating rod 15 via the servo ratio, so the servo ratio is (D/D2).

Next, when the first working pressure chamber B and the second working pressure chamber are communicated with each other by the switching valve 27, when the operating rod 15 is operated,
First and second working pressure chambers 13. D Atmosphere is introduced into both,
As a result, a pressure difference is generated between the first constant pressure chamber A and the first working pressure chamber B, and between the second constant pressure chamber C and the second working pressure chamber, and this pressure difference causes a pressure difference between the first and second working pressure chambers. piston 5.6
As a result of the displacement, the first driven rod 22 moves toward both pistons 5.
．． The mask cylinder is operated by receiving the thrust of step 6. The servo ratio at this time is approximately ((d12+d2'')/d2)(Di/D2), where the effective diameters of the first diaphragm 3 and the second diaphragm 4 are dx and d2, respectively.
) +1.

Figure 4 shows the input/output characteristics of this pressure booster. represents the result when the first working pressure chamber B and the second working pressure chamber are communicated with each other. As a result, in this pressure booster, it is possible to switch the servo ratio in two stages, and it is also possible to obtain a better servo ratio than before.

In this pressure booster, the load of the return spring 19 acts on the pressurized deformable member 18 via the first and second driven rods 22 and 23, so that the jump-in characteristic is improved. A can be easily changed by changing the set load of the return spring 19.

A switching operation as described above may be performed by providing a switching mechanism.

Further, in the above embodiments, the two-piston type is described, but it goes without saying that it can be applied to a type having a larger number of pistons.

Furthermore, for example, by independently providing the first working pressure chamber Bl and controlling the introduction of the pressure into it, it is also possible to continuously change the servo ratio.

(Effects of the Invention) As explained above in detail, the air pressure booster according to the present invention has two pistons arranged independently in series in a shell, and a pressure booster defined in the shell. This made it possible to save the room, and as a result, the following effects were obtained.

■ Unlike conventional air pressure generators, there is no connecting part between the two pistons, so it is possible to design with sufficient strength.

■ You can change the servo ratio manually or automatically,
A larger servo ratio than before can be obtained. Therefore, for example, in a loaded vehicle, the same deceleration can be obtained when the vehicle is unladen and when it is loaded.

■ Jump-in characteristics can be easily changed by changing the set load of the turn spring.

[Brief explanation of drawings]

Figure 1 is a sectional view showing the structure of a conventional pressure booster;
The figure is a correlation diagram showing the input/output characteristics of a conventional air pressure booster, Figure 3 is a sectional view showing the structure of the air pressure booster according to the present invention, and Figure 4 is the input/output of this air pressure booster. It is a correlation diagram showing characteristics. 1...Front shell 2...Back shell 3.4...Diaphragm 5...First piston 6...Second piston 8... ...Center plate (bulkhead) 15...
......Operating rod 16...1...Valve plunger 18......Press deformation member 19...
......Turnsfring 22...
・・・・・・First driven rod 23・・・・・・・・・・・・
・Second driven rod 24, 25.26...Pressure inlet 27...Switching valve patent applicant Tokico Co., Ltd. IA

Claims (1)

[Claims] (1) In an air pressure booster comprising four pressure chambers all defined in a shell by a diaphragm, two fc pistons attached to the diaphragm, and a partition installed between the two pistons, the front A first piston located at is provided with a WJl driven rod that protrudes outside the shell, a second piston located at the rear is provided with a second driven rod whose tip abuts the first driven rod, An operating rod is connected to the rear end of the second driven rod via a reaction force mechanism, and
's piston'! il- A biasing means for biasing the first piston to the return position is provided, and a first working pressure chamber in the rear part of the first piston and a first constant pressure chamber on the front side of the first piston communicate with each other. or a state in which the first working pressure chamber and the second working pressure chamber on the rear side of the second piston communicate with each other. booster.