JP2000110590A - Negative pressure actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a stopper for restricting an operation range of a negative pressure type actuator, to prevent a large force from being applied to a mounting member of the actuator, and to apply a force to a valve shaft when driving an exhaust brake valve. Prevents eccentric loads from acting. A first stopper (23) for restricting a downward operation limit of a driving rod (8) by contacting a driving rod (8) in a lower casing (2) in a lower casing (2), and attaching the driving rod (8) outside the lower casing (2). A second stopper 24 is provided for restricting the upward operation limit of the drive rod 8 by contacting the lower surface of the fixed portion 20a of the member 20.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a negative pressure actuator for driving, for example, an exhaust brake valve of an automobile.

[0002]

2. Description of the Related Art FIG. 3 shows a conventional negative pressure type actuator for driving an exhaust brake, in which a lower cup-shaped upper casing (1) and an upper cup-shaped lower casing (2) are provided. A rubber diaphragm (3) is fixed with its peripheral edge sandwiched between both casings (1) and (2). As a result, the inside of the casings (1) and (2) is partitioned into a negative pressure chamber (4) and a normal pressure chamber (5) with the diaphragm (3) as a boundary.

The central portion of the diaphragm (3) is formed by a pair of holding members having a smaller diameter than the casings (1) and (2), that is, a holding tube (6) having a bottomed cylindrical shape and a holding plate (7). By screwing a nut (9) to the upper end of a driving rod (8) that is clamped from above and below and penetrates the center of the driving rod (8),
The holding cylinder (6) and the holding plate (7) are fixed to the upper end of the driving rod (8).

The diaphragm (3) is provided with a bottomed cylindrical portion (3a) having an inner diameter substantially equal to the outer diameter of the holding cylinder (6), and has an inverted U-shaped folded curved portion ( 3b), and the curved portion (3b) and the inner cylindrical portion (3a) are provided between the inner peripheral surface of the upper and lower casings (1) and (2) and the outer peripheral surface of the holding cylinder (6). It is located in the gap.

The drive rod (8) passes through a communication hole (10) formed in the center of the lower casing (2), and its lower end has an exhaust brake valve () provided in an exhaust pipe (11) of the automobile. It is connected to a drive lever (13) that opens and closes 12).

The upper casing (1) in the negative pressure chamber (4)
A compression coil spring (14) is concentrically contracted between the upper surface of the holding cylinder and the inner bottom surface of the holding cylinder (6).
(6) is constantly biased downward.

On the upper surface of the upper casing (1), a suction pipe (15) connected to a negative pressure source is fixedly connected to the negative pressure chamber (4).

A bottom portion of the lower casing (2) is fixed to a high-strength box-shaped bracket (16) formed by drawing a steel plate with a bolt and nut (17), and this portion serves as a fixing portion. I have.

A pair of stopper bolts (18) and (19) are screwed to the side surface of the box-shaped bracket (16), and the heads of these bolts are in contact with the drive lever (13). Shoulder (13
a) The opening / closing position of the exhaust brake valve (12) is determined by abutting on each of (13b).

In the above-described negative pressure type actuator,
When the pressure in the negative pressure chamber (4) is reduced and a differential pressure is generated between the negative pressure chamber (4) and the normal pressure chamber (5), the upward pressure acting on the diaphragm (3) causes the holding cylinder (6) to move the compression coil spring (14). )
Ascends with the drive rod (8), and the shoulder (13a) of the drive lever (13)
Stops against the head of the stopper bolt (18). As a result, the exhaust brake valve (12) is closed, and the exhaust brake operates.

[0011]

In the above-mentioned negative pressure type actuator, a negative pressure is applied when the exhaust brake is operated, and a compression coil spring is used when the exhaust brake is released.
By the action of (14), the shoulders (13a) and (13b) of the drive lever (13) vigorously collide with the stopper bolts (18) and (19), and the bracket
A large impact load is repeatedly applied to (16). For this reason, the bracket (16) needs to have sufficient strength to withstand this impact load.Therefore, in the conventional actuator, the strength of the entire bracket is increased by drawing a thick steel plate or the like. And material and processing time,
There is a problem that the cost increases in terms of man-hours and the like.

Further, as described above, in the case where the stopper bolts (18) and (19) are provided on the side remote from the axis of the drive rod (8), the drive lever (13) is connected to both stopper bolts (18). (19)
When the rotation of the valve shaft (12a) is stopped by vigorously abutting the valve shaft (12a), a large eccentric load acts on the valve shaft (12a), which may cause uneven wear of the outer peripheral surface and the bearing.

The present invention has been made in view of the above-described problems, and by improving a stopper that regulates an operation range of a drive lever,
Prevents a large impact load from being applied to the entire bracket,
Accordingly, it is an object of the present invention to provide a negative pressure actuator which can use an inexpensive bracket which is easy to manufacture and which can prevent an eccentric load from being applied to a valve shaft or the like.

[0014]

According to the present invention, the above-mentioned problem is solved as follows. (1) A diaphragm between a downward cup-shaped upper casing connected to a negative pressure source and an upward cup-shaped lower casing having a bottom portion attached to a fixing portion of a mounting member via a pair of sandwiching members. By fixing the driving rod, the driving rod is partitioned into a negative pressure chamber and a normal pressure chamber with the diaphragm as a boundary, and one end is fixed to the diaphragm and the holding member, and extends outside through the lower casing. In the negative pressure actuator, a first stopper that restricts a downward operation limit of the drive rod by abutting the drive rod in the lower casing in the lower casing and the mounting member outside the lower casing. And a second stopper for restricting the upward operation limit of the driving rod by contacting the lower surface of the fixing portion of the driving rod.

(2) In the above item (1), the first and second
Is formed in a disk shape centering on the driving rod.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. The basic structure of the negative pressure actuator body such as a casing, a diaphragm, a driving rod and the like is the same as that shown in FIG. 3, and the same members are denoted by the same reference numerals and detailed description thereof will be omitted. Omitted.

In the present invention, a bracket (20) as a mounting member is used in which an upper portion of a flat steel plate is bent at a right angle to form a mounting flange (20a) as a fixing portion. 20a), the bottom of the lower casing (2) is fixed by bolts and nuts (17). In addition,
Although not shown, the bracket (20) is attached to a chassis or the like of an automobile.

The lower end of the drive rod 8 is pivotally connected to a flat drive lever 13 by a pin 21. The other end of the drive lever 13 is connected to the same exhaust brake valve as the conventional one. Omitted) Valve shaft (2
It is fixed to 2).

The lower casing (2) and the mounting flange (20)
At the upper end of the drive rod (8), which penetrates through the communication hole (10) of (a) and protrudes into the casing, immediately below the holding plate (7),
A thick disk-shaped first stopper (23) is fixed. When the exhaust brake shown in FIG.
The upper surface of (23) is in contact with the lower surface of the holding plate (7) which is lowered by the action of the compression coil spring (14).
The lower casing (2) fixed to the mounting flange (20a), which is a fixed portion, is in surface contact with the upper surface of the bottom of the lower casing (2).

A disk-shaped second stopper (24) is fixed to an intermediate portion of the driving rod (8). As shown in FIG. 2, the second stopper (24) is configured such that the negative pressure from the negative pressure source acts on the suction pipe (15), the drive rod (8) rises, and the exhaust brake valve reaches the fully closed position. When actuated, it comes into contact with the lower surface of the mounting flange (20a) in a surface contact state, and is fixed at a position where the further rise of the drive rod (8) is prevented.

[0021]

According to the first aspect of the present invention, the two stoppers for restricting the vertical movement limit of the drive rod are both provided on the drive rod, and the upper surface of the bottom of the lower casing and the bracket (mounting member). Since it abuts vertically on the lower surface of the fixed part, it is sufficient to secure only the strength of the fixed part of the bracket, unlike the conventional case, it is not necessary to make the whole bracket high strength, use a cheap and easy to manufacture bracket Can. Further, since both stoppers are provided on the driving rod to directly regulate the movement in the axial direction, even when the negative pressure type actuator of the present invention is used as an actuator for driving, for example, an exhaust brake valve, the conventional type can be used. In this way, there is no danger that an unbalanced load acts on the valve shaft or the like, causing uneven wear.

According to the second aspect of the present invention, the first and second stoppers come into contact with the lower casing and the bracket in a surface contact state, so that the abutting portion is less likely to be worn, and furthermore, the driving rod has no particular effect. Long life without bending moment. Further, when used as an actuator of an exhaust brake valve and the exhaust brake valve is fully closed, the second stopper closes a communication hole provided in a fixing portion of the bracket, so that exhaust gas leaking from the valve shaft is prevented from flowing through the casing. Intrusion into the normal pressure chamber side can be prevented.

[Brief description of the drawings]

FIG. 1 is a central longitudinal front view showing a non-operation state of a negative pressure actuator of the present invention applied to an exhaust brake valve.

FIG. 2 is a front view of a central vertical section showing an operating state.

FIG. 3 is a front view in vertical section at the center of a conventional negative pressure actuator.

[Explanation of symbols]

 (1) Upper casing (2) Lower casing (3) Diaphragm (3a) Cylindrical part (3b) Curved part (4) Negative pressure chamber (5) Normal pressure chamber (6) Clamping cylinder (clamping member) (7) Clamping Plate (clamping member) (8) Drive rod (9) Nut (10) Communication hole (11) Exhaust pipe (12) Exhaust brake valve (13) Drive lever (13a) (13b) Shoulder (14) Compression coil spring ( 15) Suction tube (16) Bracket (mounting member) (17) Bolt and nut (18) (19) Stopper bolt (20) Bracket (mounting member) (20a) Mounting flange (fixed part) (21) Pin (22) Valve Shaft (23) First stopper (24) Second stopper

Claims (2)

[Claims] 1. A pair of clamping members are interposed between a downward cup-shaped upper casing connected to a negative pressure source and an upward cup-shaped lower casing whose bottom is attached to a fixing portion of an attachment member. By fixing the diaphragm, the drive rod, which is divided into a negative pressure chamber and a normal pressure chamber with the diaphragm as a boundary, and one end of which is fixed to the diaphragm and the holding member, extends outside through the lower casing. In the negative pressure type actuator provided, a first stopper that regulates a downward operation limit of the driving rod by contacting the driving rod with an upper surface of a bottom of the lower casing inside the lower casing; A second stopper configured to abut on a lower surface of a fixing portion of the mounting member to limit an upward operation limit of the driving rod; 2. The negative pressure actuator according to claim 1, wherein the first and second stoppers are formed in a disk shape centering on a driving rod.