DE2834019A1 - PRESSURE REGULATORS OF AIR BRAKE SYSTEMS IN MOTOR VEHICLES - Google Patents

Description

Hanover, July 19, 1978 WP 3/78 - B./St

WABCO WESTINGHOUSE GmbH, HANNOVER

Pressure regulators for compressed air brake systems in motor vehicles

The invention relates to a pressure regulator for the independent control of the operating pressure of compressed air brake systems in Motor vehicles according to the preamble of claim 1.

Pressure regulators are generally used to automatically regulate the operating pressure of compressed air brake systems in Motor vehicles by allowing the compressed air conveyed by the air compressor to flow through until a pressure level set on the pressure regulator in the air tanks of the motor vehicle is reached, this pressure level being different depending on the design of the brake system Can have values.

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When the set operating pressure is reached, the pressure regulator interrupts further pressure build-up in the system and controls the compressed air still generated by the air compressor into the open air and thus switches the air compressor on Depending on the tank pressure, automatically on idle or load operation.

A pressure regulator of this type is in the design documents (European catalog) from Wabco Westinghouse GmbH in the Bl. 975 300 900 3 of the catalog group 6 described.

As a rule, the pressure regulator switches back to the delivery position, when the pressure in the brake system has fallen so far that this value is approx. 10% below the cut-off pressure level lies. This so-called switching range is subject to tight tolerances because, on the one hand, there is the pressure drop not below a certain value, which still enables braking in accordance with statutory provisions, and on the other hand, at a certain upper value, sufficient cooling of the air compressor must be guaranteed.

The disadvantage is that in the previously known pressure regulators, the switching range due to the interaction of spring forces, Frictional forces and changing active surfaces is achieved, with a large proportion of these influencing variables long-term changes is subject to changes in the switching margin can lead. So that these variables do not increase or decrease the switching range inadmissibly, one is forced to make the effective surfaces large and to keep the oils satchel of the individual parts very tight, which the functional safety as well as the production costs influenced in a negative sense.

Another disadvantage is that pressure regulators, which are intended to be used in high-pressure brake systems, for high cut-off pressures of 15 ... 20 bar, with large control pistons, require control springs with large dimensions. Switching spans in the 1O - ^ - range are particularly difficult to implement here in a size that is justifiable in terms of costs, so that particularly high demands are made on manufacturing tolerances. _{03Q008 / 0127}

The invention is based on the object of creating a pressure regulator whose factory-set switching range does not change over a long period of time changed and the switching range can be kept within small tolerances without major manufacturing effort.

According to the invention, this object is achieved by the im Claim 1 listed features solved.

Advantageous refinements of the invention can be found in the subclaims.

The assignment according to the invention of a shut-off piston controlling pilot control room as well as the arrangement of an exhaust valve in the shut-off piston to vent this pilot control room, the valve member of which is in operative connection with a plunger which forms an inlet valve with the control piston causes the pressure drop required for switching - that is, the switching range now is dependent in an advantageous manner on the soft path of the control piston must travel through when the Shut-off piston has reached its lower position until the outlet valve is open. The inlet valve with The plunger forming the control piston has the smallest possible passage cross-section that is required at the lower end adapted outer diameter, so that the frictional force that acts on the seal on the outer diameter of the plunger results, is negligibly small.

The influencing variables, which indefinitely change the switching range, were applied to a reduced to the smallest possible value.

The adjustability of the shut-off piston results the advantage that the switching range is only determined by setting the shut-off piston stroke and

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is immutable and voa. Pfcderkeünwert the rule spring, the also does not change, is dependent.

Control pistons can now be used in high-pressure systems and control springs are kept smaller, since the switching range depends on the amount of differential pressure.

The invention is explained in more detail below with the aid of the figures.

Show it:

Fig. 1 pressure regulator, diaphragm design,

Fig. 2 Pressure regulator, piston design.and

3 shows an enlarged section of the pilot control chamber associated exhaust valve.

The valve housing 1 has connections for the compressed air inlet (connection 2) from the compressed air generator and for the Compressed air outlet (connection 3) into the compressed air tank (s), with an in Check valve 4 opening the direction of flow is arranged. Between one of the inclusion of a control spring 5 Serving housing cover 6 and the valve housing 1, a membrane 7 is arranged as a control piston, which under the by means of a threaded pin adjustable tension of this control spring 5 is.

Under the membrane 7 there is a pressure chamber 9, the pressurization of which via a bore 10 is the same Pressure conditions like that of the compressed air tank is subject. The lower surface of the membrane 7 forms with the Ring surface 11 of a coaxially arranged under the membrane 7, the upper housing wall 12 penetrating sealed Hollow tappet 13, an inlet valve 7, 11, this tappet 13 with its lower end in one of one Shut-off piston 14 and the upper wall 12 formed pilot chamber 15 protrudes. This one under the top

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directed tension of a spring 16 standing as a hollow piston formed shut-off piston 14 is sealingly guided in a cylindrical housing formation 17. A arranged in the cavity 18 of the piston 14, under the Tension of a spring 19 standing valve body 20 forms an outlet valve 20/21 with a valve seat 21 fixed to the piston, which vent the pilot chamber 15 through a bore 22 of the piston 4 and outlet 25 into the atmosphere lets, it is directed against the tension of the spring 19 opening movement of the valve body 20 by means the lower end of the plunger 13 penetrating the bore 22 of the piston 14.

The exhaust valve, which is vented to the outside when the maximum operating pressure is reached in the brake system by a valve body 24 fixed to the piston and a fixed valve body Valve seat 25 is formed. This outlet valve 24/25 opens the passage of the compressed air from the the two connections 2 and 3 associated chamber 26 into the open (outlet 23). The piston stroke 27 is accessible from the outside by inserting disks or by means of a Adjustable screw setting.

The function of the pressure regulator according to Fig. 1 is as follows:

The compressed air delivered by the air compressor flows over Connection 2 into chamber 26. After the non-return valve 4 has been opened, it is passed through the one from connection 3 Line to the compressed air tanks and via hole 10 in room 9

A force now builds up in space 9, which acts on the underside of the spring 5 on the switch-off value adjusted membrane 7 acts. As soon as this force is greater than the switch-off value, the membrane 7 bulges

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upwards and the plunger 13 follows this movement as a result of the force of the spring 19 arranged under the valve body 20, so that the outlet valve 20/21 closes. With further pressure build-up in space 9, the annular surface 11 of the plunger 13 also lifts from the lower surface of the diaphragm 7, which results in the pilot chamber 15 being pressurized.

The pressure building up in this pilot chamber 15 moves the shut-off piston 14 against the force of the spring 16 down and switches the promotion to the open air via the opening outlet valve 24/25 and via outlet 23.

This state remains until the pressure acting on the control piston (diaphragm 7) decreases and the membrane, which is receding downwards after closing the valve 7/11, also moves the plunger 13 downwards, which causes an opening of the valve 20/21 against the force of the spring 19, so that the pilot control chamber 15 into the open vented and the resulting relief of the graduated piston 14 closes the outlet valve 24/25.

The pressure regulator shown in FIG. 2 is identical with the parts of the regulator shown in FIG. 1 Provided reference numbers. Only the piston arranged instead of the diaphragm 7 has the reference number 7a, and instead of the housing cover 6, the corresponding upper housing part is marked here with 6a.

The structure and function are otherwise as with regard to FIG. 1 described.

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Claims (6)

283A019 Hanover, July 20, 1978 WP 3/78 - B./St, HANNOVER patent claims 1. Pressure regulator for the automatic control of the operating pressure of compressed air brake systems in motor vehicles, which allows compressed air supplied by a compressed air generator system to flow through the brake system's reservoir until a maximum container or operating pressure is reached, with a control piston responding to the maximum operating pressure built up in a pressure chamber, its maximum Stroke position switches off the delivery of compressed air into the storage tank by the stroke of a shut-off piston, which can be pressurized with the maximum pressure via an opening inlet valve, opens an outlet valve venting into the atmosphere, characterized in that one above the shut-off piston (14) 030008/012 7 ORIGINAL INSPECTED separate pilot chamber (15) with the below the Control piston (7) located pressure chamber (9) over the cavity of a plunger (13), its upper and lower ends protrudes into the respective chambers (9 or 15), in connection stands that the upper annular surface (11) of the plunger (15) with the lower surface of the piston (7) the connection between the pressure chamber (9) and the pilot chamber (15) producing the inlet valve (7/11) and that the lower butt end with one inside the shuttering tkolbens (14) arranged movable valve member (20), which with a piston-fixed valve seat (21) of the shut-off piston (14) into the pilot control chamber (15) forms venting outlet valve (20/21), is in operative connection. 2. Pressure regulator according to claim 1, characterized in that the control piston consists of a membrane (7). 3. Pressure regulator according to claim 1, characterized in that the control piston consists of a cylindrical piston (7a). 4. Pressure regulator according to claims 1 to 3, characterized in that the hollow plunger (13) is guided pressure-tight in the housing wall. 5. Pressure regulator according to claims 1 to 4, characterized in that the valve member (20), which is movably arranged in the shut-off piston (14) and operatively connected to the hollow plunger (13), is actuated by a spring ( 19) is stretched in the valve closing direction. 6. Pressure regulator according to claims 1 and 2, characterized in that the stroke (27) of the shut-off piston (14) is adjustable. 030008/0127