DE3500055A1 - Central valve in or on master-cylinder pistons - Google Patents

Abstract

The invention relates to a central valve in or on master-cylinder pistons of hydraulic systems, which in the open state permits a pressure balance between the pressure space of the master cylinder and the supply tank. <IMAGE>

Description

FAG Kugelfischer Georg Schäfer R-RS-l-808-re-st Limited partnership on shares 02.01.1985

Central valve in or on the master cylinder piston of hydraulic systems

The invention relates to a central valve in or on master cylinder pistons of hydraulic systems, which for a pressure equalization between the follow-up tank and the pressure chamber of the master cylinder in the non-actuated Condition.

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Such central valves are known in brake master cylinders and, for example, in DE-AS 15 05 301 and DE-OS 19 63 13.4 disclosed.

They are used to open the pressure chamber of the master cylinder with the expansion tank when the brake is not actuated. * ter connect to an unwanted pressure increase

(for example, due to the temperature rise of the pressure medium) while the brake is being applied this connection must be closed in order to be able to build up the required brake pressure.

The valve closes with each piston stroke via a pretensioned compression spring.

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The disadvantage of the known central valves is undefined closing time, as it is due to the fluctuations in the spring force subject, as well as the risk of total failure of the unit in the event of a spring break.

Furthermore, the dimensions of the working piston must allow the compression spring to be accommodated in its relaxed position, whereby the working piston must be made larger than its primary task requires.

The invention is based on the object of creating a central valve in a master cylinder piston that

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allowed, the demand for compact built-in units

comply without following the disadvantages indicated. 5

The solution to the problem results from the characterizing part of claim 1. Advantageous embodiments result from claims 2-4.

It shows:

FIG. 1 shows the longitudinal section of a tandem master brake cylinder with a central valve according to the invention in the basic position
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Figure 2 shows the longitudinal section of a master cylinder with the invention Central valve in basic position

Figure 3 shows a partial section of the master cylinder according to Figure 2 *

FIG. 4 shows a section along the line A-A according to FIG

In Figure 1, a tandem master cylinder is shown in longitudinal section, which has the following main components:

the housing 1 with stepped bore 2 and the primary piston 3 with piston rod, which is arranged axially displaceably therein 4 and the secondary piston 5 with central valve 6 as well as the connections 10, 10a for the after-flow tank,

In its central area, the secondary piston has a longitudinal slot 11 through which one is fastened in the housing 1 Grooved pin 7 is passed, which secures the secondary piston 5 against rotation. At his the pressure room 8, the end facing the secondary piston 5 has a stepped bore 9, the outlet of which is as follows

■ ι lim

is designed that through the longitudinal slot 11 a connection of the pressure chamber 8 with the follow-up tank connection. The larger diameter section of the stepped bore 9, which is closed by a centrally drilled magnet 15, surrounds the valve body of the central ven tils 6. In the smaller-diameter section, its tappet 13 is guided, which is in the basic position on the through grooved pin 7 guided through the longitudinal slot 11. There is a permanent magnet on the head of the central valve 6 16 arranged so that it faces the magnet 15 homopolar and the resulting repulsive force on the Central valve 6 acts.

When the brake is actuated, the piston rod 4 pushes the primary piston 3 into the pressure chamber 17 and over the compression spring 18, the secondary piston 5 is pushed into the pressure chamber 8 against the force of the compression spring 19. The tappet 13 of the central valve 6 disengages

_{t of} the grooved pin 7, the repulsive force of the magnets 15, 16 ι

presses the central valve 6 on its seat 14 and it can

'i. the brake pressure builds up in pressure chamber 8.

When the brake is released, the secondary piston 5 and the primary piston 3 via the compression spring 18, 19 into the Home position pressed. The central valve 6 is when Starting his plunger 13 on the grooved pin 7 against the force of the magnets 15, 16 and pushed open between the Pressure chamber 8 and the after-flow tank (not shown) can be pressure equalized via connection 10.

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Figure 2 shows a master cylinder in section, which essentially consists of the following components:

the housing 20 with continuous stepped bore 21, the axially displaceable piston 22 with piston rod 23, the disk 24, the central valve 25 and the sleeve 26 for the storage container connection and the pressure connection 2 7.

For a better understanding, reference is made to Figures 3 and 4 at the same time.

The sleeve 26 is drilled through in a stepped manner and a ring magnet 30 is located in its larger-diameter bore 29 on the paragraph 28 arranged such that it is with the sealing ring 32 in front of it and the spacer sleeve 3 7 of the disk 24 is fixed. On the sealing ring 32, the seat 33 is arranged, which is the seat of the ferromagnetic Central valve 25 forms.

The central valve 25 is with a flexible cord-like connection 34 through a, attached to the sleeve 26 supporting, * having a pear-shaped bore 35 Disk 24 is connected to the piston 22 through it.

When the piston rod 23 is loaded, the piston 22 moves into the pressure chamber 31. The cord 34 is relaxed, the ferromagnetic, hemispherical central valve 25 is controlled by the ring magnet 30 is pulled onto its seat 33 and the hydraulic pressure can build up in the pressure chamber 31. With relief the piston rod 23 is the piston 22 by the compression spring 36 tied to it in its starting position pushed.

The central valve 25 is pulled by the cord 34 against the magnetic force from its sealing seat 33 into the bore 35 of the disk 24.
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Claims (4)

FAG Kugelfischer Georg Schäfer R-RS-l ~ 8O8-re-se Limited partnership on shares 02.01.1985 Central valve in or on master cylinder piston of hydraulic systems Claims 1. Central valve in or on the master cylinder piston of hydraulic systems, characterized in that the central valve (6, 25) can be lifted from its seat (14, 33) against the force of one or more magnets (15, 16 and 30). 2. Central valve according to claim 1, characterized in that the head of the central valve (6) is provided with a permanent magnet (16) to which a further magnet (15) is arranged in a piston-proof, homopolar repulsive manner opposite. 3. Central valve according to claim 1, characterized in that the central valve (6) consists of a ferromagnetic material and is in operative connection with a permanent magnet (30) arranged in front of or behind the valve seat. 4. Central valve according to claim 1 and 3, characterized in that the valve body (25) is in operative connection with the cylinder piston (22) via a flexible, cord-like connection (34).