JPS6044174B2 - Multi-circuit protection valve for compressed air equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a multi-circuit protection valve connected between an air compressor and a plurality of compressed air supply circuits, the protection valve having an overflow valve in each compressed air supply circuit. , the valve closing member of each of these overflow valves is pressed against the valve seat by an adjustable pressure-forming spring, and leaves the valve seat when the overflow pressure of the overflow valve is reached, allowing the flow of compressed air. The present invention relates to a multi-circuit protection valve for a compressed air system, particularly a compressed air braking system for a road vehicle.

Due to the unavoidable setting tolerances when setting the spring force of the pressure-forming spring, it is almost impossible to set the overflow valves of multicircuit protection valves identically.

This means that the overflow valves have different opening pressures. A pressure difference of approximately 0.3 bar is to be expected as a normal setting tolerance. If a setting tolerance exists, the circuit with the lower setting is filled with compressed air first, followed by the circuit with the higher setting. Now, even if the lower set circuit becomes defective and the pressure in this circuit disappears, it is necessary to be able to fill the higher set healthy circuit. In order to meet this requirement, known multi-circuit protection valves each have a fixed throttle connected in front of each overflow valve. The resulting increased pressure in the supply line reaches a high opening pressure, which is caused by the setting tolerance of the higher overflow valve. This device has the disadvantage of a small flow cross section, especially for high flow rates.

Because even if a healthy circuit is not yet filled,
This is because a pressure is created in the supply conduit which is greater than the cut-off value of the pressure regulator. In order to eliminate this drawback, the setting tolerances of the overflow valve must be narrowed, since if the throttling action of the throttle is reduced, the dynamic pressure generated by the throttle is reduced. However, this reduction in the setting tolerance is almost impossible, as mentioned at the beginning. A conical pin protrusion is provided on the valve closing member of the overflow valve of the multi-circuit protection valve, and the pin protrusion and the hole in the supply conduit from the compressor allow the stroke of the valve closing member. The formation of a related variable diaphragm is known from DE 21 43 733 A1.

That is, in FIG. 5 showing the four-circuit protection valve, the compressed air reservoir connections 112 and 1 belonging to braking circuit 1 and
12'', a central connecting conduit section 116 branches off via non-return valves 115 and 115'' and leads to overflow valves 117, 118 belonging to brake circuits (1) and (2). Two side passages 119, 119″ connected to the central connecting conduit 116
At the end of each one central valve seat 120 or one
2 ``There is. Behind each valve seat 120 or 12'' there is an annular space 121 or 12'' delimited by a valve piston 123 or 123'' as a movable wall.
Each valve piston 123 or 123'' has a valve closing member 122 or 122'' on its end face. screw 124
or 124″ adjustable spring 125 or 12
A force of 5'' forces the valve closing member 122 or 122'' onto the valve seat 120 or 12''. In front of the valve seat 120 or 12'' in the direction of flow there is a central hole 126 or 126'' into which the conical pin protrusion 127 or 127'' of the valve closing member 122 or 122'' enters. Together, they form a variable aperture 130 or 13'. Therefore, an annular space 131 or 13'' is formed between the throttle 130 or 13'' and the valve seat 120 or 12'', and when the overflow valve is closed, the pin protrusion receives the primary pressure from the compressor. 127 or 127
'' is also always receiving primary pressure. Now, when the secondary pressure is supplied to the brake circuit 1, ■, the check valves 115, 115'',
Via the central connecting conduit 116 and the side passages 119, 119'' through the aperture 130, 13'' into the annular space 131, 1.
3" and opens the overflow valves 117, 118 against the force of springs 125, 125" to reach the brake circuits (1) and (3).

In this multi-circuit protection valve, the annular surfaces of the valve closing members 122, 122'' belonging to the annular spaces 131, 131'' and the pin protrusion 1
It is extremely difficult to align the surfaces receiving the primary pressure of the 27 and 12 guns with each other in a manner that allows them to function satisfactorily.

Furthermore, the necessary small flow cross section of the apertures 130, 13' is
Due to the use of an annular surface as the diaphragm, it is also impossible to maintain it with sufficient precision. It is an object of the present invention to ensure that, in the event of a failure of a compressed air supply circuit, the remaining healthy compressed air supply circuit is refilled accurately even if this circuit is evacuated to atmospheric pressure. be.

For this purpose, a multi-circuit protection valve is connected between an air compressor and a plurality of compressed air supply circuits and includes an adjustable overflow valve having a valve seat and a valve closing member for each compressed air supply circuit. At an overflow pressure determined by the force of the pressure forming spring and the pressure of the compressed air supply circuit, the valve closing member separates from the valve seat, causing the overflow valve to connect with the compressed air supply circuit such as the air compressor, and prevent overflow. When the pressure height is inversely related to the pressure in the compressed air supply circuit, the valve closing member has a surface that can receive the pressure of the air compressor in the opening direction, and there is no pressure in the compressed air supply circuit. Where the overflow pressure of the overflow valve is within a tolerance band between a lower tolerance limit pressure and an upper tolerance limit pressure, the invention provides that the valve closing members or valve seats of the overflow valve are arranged concentrically with respect to each other. 2
having two annular fins, these fins dividing the face of the valve closing member capable of receiving air compressor pressure into two concentric working surfaces, the outer annular fin being slightly shorter than the inner annular fin and at least as long as the inner annular fin. The fin or its opposing surface is configured to be elastically deformable, the outer working surface is connected to the inner working surface via a crack in the inner annular fin, and the ratio of the sum of both working surfaces to the inner working surface is at least within the upper tolerance limit. Equal to the ratio between the pressure and the lower tolerance limit pressure, when only the outer annular fin is away from the valve seat, the crack will throttle the connection between the air compressor and the compressed air supply circuit, even if the air compressor discharge volume is low. .

Embodiments of the present invention will be described below with reference to the drawings. The two-circuit protection valve shown in FIG. 1 has connections 11 and 12. The connection 11 belongs to a brake circuit as a compressed air supply circuit, and the connection 12 belongs to a brake circuit as a further compressed air supply circuit. One air compressor, not shown, leads to the pressure-forming chambers 13, 14. pressure forming chamber 13,
14 is connected by two overflow valves 1, 11 to the connecting portion 11,
It can be isolated from the connection chambers 19, 21 with 12.

Diaphragm 2 between housing members 22, 23, 24
5, 26 are stretched, and these diaphragms 25,
Valve closing member 15 of overflow valve 1, 11 on one side of 26,
17 are supported and on the other side these valve closing members 15
, 17 are supported, the initial stress of these springs 27, 28 is equal to the screws 29, 31
Adjustable by. The selected initial stress of the pressure-building springs 27, 28 determines the overflow pressure (opening pressure) of the overflow valves 1, 11 in the pressure-building chambers 13, 14.
Furthermore, the valve closing elements 15, 17 are each acted upon by a closing spring 32, 33 which acts in the closing direction. These closing springs 32, 33 are not critical according to the invention and can also be omitted. This kind of overflow valve 1, 11
As a general property of
It is also determined by the pressure built up in the associated overflow valve (marked 1, 11 correspondingly). That is, the valve closing members 15, 17 are subjected to a force in the direction of closing the overflow valve by the pressure-forming springs 27, 28. On the other hand, in the opening direction of the overflow valve, a pressure forming chamber 1 is provided on the working surface of the valve closing members 15 and 17.
3, 14 pressure (inflow side), and diaphragm 25,
The working surface of 26 receives the pressure of the compressed air supply circuits 1 and 11 (outflow side). Since the valve closing elements 15, 17 are likewise subjected to the outflow pressure on their rear surfaces, the active surface of the diaphragms 25, 26 is obtained as the difference between the total diaphragm surface and the active surface of the valve closing elements 15, 17. Therefore, overflow valve 1,
The overflow pressure of 11 is determined by the initial stress of the pressure forming springs 27, 28 when there is no pressure in the compressed air supply circuits 1, 11, but as pressure is built up in the compressed air supply circuits 1, 11, , this overflow pressure becomes smaller. The greater the pressure created in the compressed air supply circuits 1, 11 in this way, the smaller the pressure in the pressure creation chambers 13, 14 required to overcome the force of the pressure creation springs 27, 28 and open the overflow valve. . That is, the height of the overflow pressure has an inverse relationship to the pressure of the compressed air supply circuit. Overflow valve 1 and 1
1 are formed in the same way.

The valve closing members 15, 17 are pressed against valve seats 16, 18 provided within the housing 22. The valve closing members 15,
Elastic valve rings 36, 37 are inserted into the closing surfaces 34, 35 (see FIGS. 2 to 4) of 17, and these valve rings 34, 3
5 is an annular fin 3 with a triangular cross section arranged concentrically with each other.
8 and 39, 41 and 42, respectively.
These fins divide the surface of the valve closing member that can receive the pressure of the air compressor into two concentric working surfaces, such that the ratio of the sum of both the outer and inner working surfaces to the inner working surface is It is equal to or greater than the ratio of the upper tolerance limit pressure and the lower tolerance limit pressure of the overflow valve. outer annular fin 39,
42 is formed slightly lower than the inner annular fins 38, 41. In actual experiments, it was found that outer annular fins 39, 42 that are lower by 0.1 W$L are better. The inner annular fins 38, 41 have cracks 43, 4 that act as apertures.
It has 4. The operation of this two-circuit protection valve will be explained below.

When a pressure is built up in the pressure-building chamber 13 by the supply of compressed air from the air compressor, this pressure reaches the outer working surface from the inner working surface through the crack 43. This pressure therefore acts on the sum of the inner working surface and the outer working surface, ie on the total working surface. When the force generated by the pressure acting on this entire active surface is large enough to overcome the force of the pressure-building spring 27, the valve closing member 15 is lifted and the outer annular fin 39 is moved against the valve seat 16. be separated from The pressure at this time is the overflow pressure of the overflow valve 1 when there is no pressure in the compressed air supply circuit 1. The valve closing member 15 has an outer annular fin 39 separated from the valve seat 16 and an inner annular fin 38 still attached to the valve seat 16.
remain for a short period of time in a position not far from the

The overflow pressure that hitherto acted on the outer active surface then escapes through the annular gap formed between the raised outer annular fin 39 and the valve seat 16. In this state, only a small amount of air is supplied from the inner working surface through the crack 43 which acts as a throttle, so that in this state no significant pressure is maintained under the outer working surface. Therefore, to a large extent only the inner working surface is effective. However, the overflow pressure cannot maintain said position of the valve closing member 15 through this small surface, and the valve closing member 15 is pushed back towards the valve seat 16 and the outer annular fin 39 closes again. The overflow pressure now acts again on all working surfaces, and the valve closing member 15 is forced into the outer annular fin. 39 is released and the inner annular fin 38 moves back into the closed position and the cycle described above is repeated. The valve closing member 15 therefore enters a flutter phase. In this flutter stage, the outer annular fin 39
Each time the air is removed, some air is compressed from the pressure-forming chamber 13. It flows into the air supply circuit 1. As a result, a pressure gradually builds up in this compressed air supply circuit 1 and acts upwardly against the pressure-building spring 27 on the diaphragm 25 , thereby exerting an effect on the pressure in the pressure-building chamber 13 via the valve closing element 15 . will be assisted. If the output of the pneumatic compressor is of a suitable magnitude, the pressure within the pressure-forming chamber 13 and thus on the entire or inner working surface of the valve closing member 15 also increases. Due to the pressure build-up in the compressed air supply circuit 1 or its influence on the pressure in the pressure build-up chamber 13, the valve closing member 15 initially opens with the outer annular fin 39 open and the product =^ko1:
;′Heir〃? Ken-ni 38 also separates from the valve seat 16, and the crack 43
The throttling effect of is eliminated.

Since the air compressor continues to discharge, the pressure in the pressure-forming chamber 13 and the pressure in the compressed air supply circuit 1 approach each other, excluding the slight pressure difference defined by the closing spring 32. The closing spring 32 prevents backflow from the compressed air supply circuit and is not important to the invention and may be omitted. As the pressure in the pressure-building chamber 13 and the compressed air supply circuit 1 increases, the diaphragm 25 deflects more and more upwards against the force of the pressure-building spring 27 .
7 is compressed. The valve closing member 15 follows the deflection of the diaphragm 25 until the deflection of the diaphragm 25 is limited because a spring catch (not shown) abuts a stop (not shown) on the housing part 23 . An increasing valve cross section is then opened between the inner annular fin 38 and the valve seat 16 until the overflow valve 1 is completely opened with the maximum possible deflection of the diaphragm 25. After the above-mentioned pressures approach each other, the pressure is further increased in the pressure generation chamber 13 and the compressed air supply circuit 1 to the full pressure of the air compressor. The duration of the aforementioned flutter phase is related to the magnitude of the air compressor output.

At large delivery volumes, the flutter phase of the valve closing member 15 is short or does not occur at all. Because the pressure formation chamber 13
The pressure within the compressed air supply circuit 1 rapidly exceeds the overflow pressure and reaches a certain value, i.e. when the inner working surface of the valve closing member 15
The inner annular fin 38 can be pressed against the valve seat 16 without the aid of pressure.
This is because it rises to a value that is sufficient to move it away from. As can be seen from the above description, when the overflow valve 1 is closed, if there is pressure in the compressed air supply circuit 1, due to the assistance of this pressure acting through the diaphragm 25, the valve closing member 15 undergoes a flutter phase. starts at low overflow pressure.

The above-mentioned action is performed in the same way for the other overflow valve 11 of the multi-circuit protection valve.

Next, the cooperative action of overflow valves 1 and 11 will be explained.

First, when the total pressure of the air compressor is 10 bar and the compressed air supply circuits 1 and 11 are evacuated and have no pressure, the overflow valve 1 has an overflow pressure of 7.0 bar, and the overflow valve 11 has an overflow pressure of 7.0 bar.
Assume that has an overflow pressure of 7.3 bar. The tolerance range of the overflow pressures of both overflow valves 1, 11 therefore lies between 7.0 bar and 7.3 bar, with a lower tolerance pressure of 7.0 bar and an upper tolerance pressure of 7.3 bar. Furthermore, the ratio of the total working surface to the inner working surface of the valve closing members 15, 17 is 7.5:7.0 (greater than the minimum ratio of 7.3:7.0 between the upper tolerance limit pressure and the lower tolerance limit pressure), i.e. Assume 1.0714:1. It is assumed that both compressed air supply circuits 1 and 11 are healthy. The above-mentioned function of the overflow valve 1 is realized by the pressure-forming chambers 13, 1 communicating with each other.
Starting at a pressure of 7.0 bar within 4. At the latest, after the pressure forming chamber 13 and the compressed air supply circuit 1 reach the same pressure,
The pressure in the pressure-forming chambers 13, 14 rises to 7.3 bar, so that the action described above for the overflow valve 1 also begins on the overflow valve 11. Therefore, if both compressed air supply circuits 1 and 11 are healthy, both overflow valves 1
, 11 is not a problem. Now, it is assumed that the compressed air supply circuit 1, which has a lower tolerance limit pressure of 7.0 bar as an overflow pressure, has a defect, and air leaks from this defect.

Generally, there is residual pressure in the compressed air supply circuit 11 due to previous driving operation, but the defective compressed air supply circuit 1
There is no pressure due to this defect. In this case, this defect is not a problem as long as the residual pressure in the compressed air supply circuit 11 is sufficient to reduce the overflow pressure in the overflow valve 11 to below 0.7 bar. However, if the compressed air supply circuit 11 does not have such residual pressure, and in the worst case, there is no pressure, a problem will arise. That is, in this case, if the discharge amount of the air compressor is small, the conventional device cannot open the overflow valve 11 and fill the compressed air supply circuit 11 with compressed air. In this case, in the present invention, the pressure forming chambers 13, 1
At a pressure of 7.0 bar in 4, the valve closing member 15 enters its flutter phase, allowing a small amount of air to enter the compressed air supply circuit 1, which air escapes through the defect. Therefore, no pressure is generated in the compressed air supply circuit 1 to support the pressure in the pressure forming chamber 13. However, according to the present invention, the crack 43 is configured as a throttle, so even if the air compressor discharges only a small amount during idling of a vehicle engine, the crack 43
This amount is larger than the amount of air flowing into the compressed air supply circuit 1 through 3. According to the invention, the ratio of the sum of the outer and inner working surfaces of the valve closing member 15 to the inner working surface is at least equal to the ratio of the upper tolerance limit pressure and the lower tolerance limit pressure, so that the pressure-forming chamber 13
, 14 assumes a value of 7.5 bar, the valve closing member 15 remains in its flutter phase. But 7.3b
From the tolerance upper limit pressure of ar, the valve closing member 1 of the overflow valve 11
7 begins to operate as described above, this overflow valve 1
1 eventually reaches its stable fully open position, so that a healthy compressed air filling of the compressed air supply circuit 11 is guaranteed. As mentioned above, this already appears at the minimum area ratio of 7.3:7.0=1.0429:1, that is, the ratio of the upper tolerance limit pressure to the lower tolerance limit pressure. Thus, according to the present invention, if the compressed air supply circuit 1 fails, for example, a healthy compressed air supply circuit 11 having an overflow valve 11 set to a higher overflow pressure than the overflow valve 1 of this circuit 1 has no pressure. This circuit 11 can also be reliably filled.

Moreover, since the cracks 43 and 44 are used as apertures, the flow cross section can be maintained with sufficient accuracy.
It should be noted that the diaphragms 25, 26 can be omitted if the valve closing members 15, 17 are designed as stepped pistons, which are sealed in the housing parts 23, 24 and can be moved against the pressure-forming springs 27, 28. be able to.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view of a two-circuit protection valve with an overflow valve formed according to the present invention, FIG. 2 is a bottom view of a valve closing member, and FIG. 3 is a valve closing according to FIG. FIG. 4 is a longitudinal sectional view of the member, and FIG. 4 is an enlarged view of the part marked ■ in FIG. 1. FIG. 5 is a sectional view of a conventional multi-circuit protection valve. 1, 11... Overflow valve, 15, 17...
Valve closing member, 16, 18...Valve seat, 27, 28...
...Pressure formation spring, 38, 39, 41, 42...
...Annular fin, 43,44...1st damage.

Claims (1)

[Claims] 1 A multi-circuit protection valve is connected between an air compressor and a plurality of compressed air supply circuits, an overflow valve having a valve seat 16, 18 and a valve closing member 15, 17 for each compressed air supply circuit. and at an overflow pressure determined by the force of the adjustable pressure-forming springs 27, 28 and the pressure of the compressed air supply circuit, the valve closing member 15, 17 moves away from the valve seat 16, 18, causing the overflow valve to open. The air compressor and the compressed air supply circuit are connected, the height of the overflow pressure has an inverse relationship to the pressure of the compressed air supply circuit, and the valve closing member 15,1
7 has a surface that can receive the pressure of the air compressor in the opening direction, and when there is no pressure in the compressed air supply circuit, the overflow pressure of the overflow valve is within the tolerance band between the tolerance lower limit pressure and the tolerance upper limit pressure. In some, the valve closing member 15, 17 or the valve seat 16, 18 of the overflow valve has two annular fins 38, 39, 41, 42 arranged concentrically with respect to each other, which fins are connected to the air compressor pressure. The surface of the valve closure member 15, 17 that can receive the valve closure member 15, 17 is divided into two concentric working surfaces, the outer annular fin 39, 42 intersecting the inner annular fin 38, 4.
1 and at least the inner annular fins 38, 41
Alternatively, the opposing surfaces thereof are formed to be elastically deformable, and the outer working surface is connected to the inner working surface via cracks 43 and 44 in the inner annular fins 38 and 41, and the ratio of the sum of both working surfaces and the inner working surface is is at least equal to the ratio of the upper tolerance limit pressure and the lower tolerance limit pressure, and only the outer annular fins 39, 42 are in contact with the valve seat 16.
, 18, the cracks 43, 44 throttle the connection between the air compressor and the compressed air supply circuit, even if the discharge amount of the air compressor is small. Multi-circuit protection valve for vehicle compressed air equipment with a supply circuit.