DE2234919A1 - DEVICE FOR CONTROLLING VALVES - Google Patents

Description

234919

Maschinenfabrik Augsburg-Nürnberg Aktiengesellschaft 89 Augsburg, Stadtbachstrasse 1

P. B. 2683 Augsburg, July 13, 1972

Device for controlling valves

The invention relates to a device for controlling valves, especially fuel one injection valves, with a high pressure pump, which is connected to the valve to be controlled via a pressure line.

Fuel is a fuel valve that is usually used in diesel engines iSTade! valves are designed for tightness, jet shape and correct setting of the injection pressure checked. To build up the pressure required for this, manually using compressed air or electrically driven high pressure pumps use. The pump is usually connected to the valve via a rigid pressure piece. As a result of the low flexibility of this rigid system, the opening pressure of the valve becomes the pressure at that of the valve needle lifted from their seat and released a cross-section from ström will be reached very soon. Since the Puimpen used in the Usually only have a very small delivery volume per stroke, the delivered amount is not sufficient to prevent the loss of pressure medium at the valve cover so that the pressure in the pressure piece collapses very quickly.

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The valve breaks and the valve is closed again by pressing the valve needle onto its seat, for example by a valve spring . A further rapid increase in pressure results in a brief spraying again with a subsequent collapse in pressure when the opening pressure is reached. It is therefore not possible to generate a long lasting, powerful spray jet, rather the valve needle executes so-called fluttering movements which in no way correspond to the operating behavior of a valve built into an engine. The result of such a test can therefore only be of limited significance. Because of the poor verifiability, too many valves were previously considered to be inoperable.

Based on this, it is the object of the present invention, with To create a device of the type mentioned at the outset with as little effort as possible, in which a device for checking the valve conditions that are largely similar to the operating conditions of a valve can be maintained for a sufficient period of time.

This object is achieved in that the volume of the pressure line in the pressure range between the closing pressure and the opening pressure of the valve can be increased against a spring force to accommodate a predetermined storage volume. In this case, even with the valve closed, a sufficient amount of pressure medium is accumulated in the pressure line, which after reaching the opening pressure of the valve must flow out through the valve until the closing pressure is reached. The advantages that can be achieved in this way are particularly to be seen in the fact that the spraying process can now continue until the entire storage volume has flowed out through the valve. This allows a strong ab «

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spray jet can be generated with full needle lift, with the temporal Duration can be well above the real injection time. Since now a long time is available for observation and the operating conditions are imitated to a sufficient extent, a test of this type can be ascribed a high level of informative value. the.

In an advantageous embodiment of the invention is for education An elastically stretchable high-pressure rubber hose is provided for the pressure line. Without any additional effort, you can see here due to the elastic stretching of the high-pressure rubber hose, a sufficient one Storage volume. In addition, flexible connection hoses are very easy to handle because there are no fixed cables a certain cable routing is necessary. must be held.

Characterized in that the high-pressure rubber hose is surrounded by at least one steel wire armouring on which the high-pressure rubber hose is attached comes into contact with load and thus limits the elastic expansion of the high-pressure rubber hose, the high-pressure rubber hose is advantageously protected against inadmissible expansion and subsequent bursting.

A first, radially inner one, directly on the surface, is expedient of the high-pressure rubber hose arranged steel wire reinforcement with a soft spring characteristic and a second, radially outer, one steel wire reinforcement, which is arranged at a radial distance from the first, is provided with a hard spring characteristic. Through the radially inner steel wire reinforcement is here an extensive one

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Equalization of the local resilience of the high pressure rubber hose achieved. The high-pressure rubber hose comes into contact with the outer steel wire reinforcement under full load, which means stretching beyond the specified amount is almost impossible. The distance provided between the two steel wire reinforcements allows the extent of the elastic expansion of the high-pressure rubber to be determined adjust hose.

Further features and advantages of the invention emerge from the following description of several exemplary embodiments the drawing in conjunction with the subclaims.

Show it

Figure 1 shows a device according to the invention

for spray control of valves,

Figure 2 shows an embodiment of the pressure

management,

FIG. 3 shows a further embodiment, for example

Pressure line,

Figure 4 is a volume «pressure diagram of a

such pressure line.

In Figure 1, 1 denotes a high pressure pump, which has a Pressure port 2 with a distribution piece 3 is in connection. The high pressure pump 1 is usually operated with compressed air. There are however, manually or electrically operated pumps are also conceivable. To the

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Simplifying the pump structure and reducing the forces to be absorbed by the pump find pumps with very small Delivery volume per stroke use. Several pressure lines 4 can be connected to the distribution piece 3, each of which leads to a valve 5, which is designed as a needle valve in the case shown, lead that to be checked for leaks, jet shape and correct setting of the spray pressure. At the outlet of the distributor 3 Check valves 6 can be provided, which prevent pressure medium from flowing back from the pressure line 4 to the pump 1 and thus prevent the individual pressure lines from influencing one another. A return then leads from distribution piece 3 « Line 7 back to the pump, via which the pressure medium that is not pressed into the pressure lines can flow back to the pump 1. In the area the connection of the pressure line 4 to the valve 5 is provided with a safety valve 8, which then responds immediately and connects the pressure line 4 to the atmosphere via an emergency discharge line 9, when the pressure in the pressure line 4 exceeds an adjustable limit value. Are useful as check valves 6 and as Safety valves 8 spring-loaded ball valves are provided. The pressure medium injected to test the valve 5 is in a tub caught. From the "tub 10 a return line to the pump lead back. However, the tub 10, as soon as it is filled, can also be emptied by hand into a storage container provided on the pump 1 will.

The pressure medium conveyed by the pump 1, as a rule, is used as the pressure medium Anticorit, as long as the pressure is in the Pressure line 4 the opening pressure of the valve 5, the pressure at which

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-bir the needle is possibly lifted from its seat against the force of a valve spring, not reached, stored in the pressure line 4. For this purpose, the pressure line 4 is designed to be elastically stretchable or is connected to a storage space. "When the pressure in the pressure line 4 has reached the opening pressure of the valve 5, an outflow cross-section is released and the pressure medium can escape into the tub 10. At this point in time, the shape of the jet indicated at 11 can be checked very precisely Volume of the pressure line 4, either due to the elastic rebound of the pressure line 4 itself or a previously tensioned spring or membrane, the entire medium stored in the pressure line 4 is sprayed off via the valve 5. This allows a very long-lasting spraying process to be achieved, The valve needle is pressed onto its sealing seat again when the pressure in the pressure line 4 has dropped to the closing pressure of the valve 5. The closing pressure of a valve is always below the opening pressure because it is greater when the valve is closed effective areas come into play In terms of the delivery volume per stroke of the high pressure pump 1, longer periods of time are required to build up a pressure corresponding to the opening pressure of the valve 5 in the pressure line 4, there are large intervals between the individual spraying processes. In these intervals, the valve 5 can easily be checked for leaks. If only a check of the tightness is to be carried out, the pressure limit value at the safety valve 8 could for example also be set so that the opening pressure of the valve 5 is not reached, but a very high pressure at the

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Valve needle attacks. The correct setting of the injection pressure can be easily monitored in a simple manner by means of a manometer 12, which is arranged on the distributor 3 in the case shown.

In Figure 2 is a section through a pressure medium line 4 is shown, which itself has a very high elastic expandability. In the present case, the pressure line is formed by a high-pressure rubber hose 13. The rubber hose has a very large wall thickness to absorb the high internal pressures. On the surface of the high-pressure rubber hose 13, a steel wire reinforcement 14 is provided ₃ which is advantageously formed by a thin-wire steel wire mesh. The steel wire reinforcement 14 has a very soft spring characteristic, so that an elastic expansion of the high-pressure rubber hose 13 is fully guaranteed. At a radial distance from the radially inner steel wire reinforcement 14, a further radially outer steel wire reinforcement 15 is provided, which is formed by a thick-wire steel wire mesh. The spring characteristic of the thick-wire steel wire reinforcement 15 rises very steeply, so that large forces are required even for a slight elongation. If a pressure builds up in the cavity 16, the high-pressure rubber hose 13 with the radially inner steel wire reinforcement 14 initially expands until the outer surface comes fully into contact with the steel wire reinforcement 14. The expansion path of the high-pressure rubber hose 13 is accordingly limited by the distance between the steel wire reinforcement 14 and the surface.

In the embodiment shown in Figure 3, the pressure « Line 4 is formed by a tube 17 which is in communication with a cylinder 18 in which a piston 19 loaded by a spring

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20 is sealingly performed. When the pressure in the pressure line increases, the piston 20 moves against the force of the spring 19 above, so that the space 21 located below the piston in the case shown is enlarged. That via the bore 22 from the When the valve is open, pressure medium entering the space 21 is returned to the pipe 17 by the force of the spring 19. presses. The largest volume of the space 21 is reached when the turns of the spring 19 lie on top of one another. To prevent « tion of wear on the spring 19 can, however, also be provided a stop against which the piston 20 comes to rest.

In the diagram shown in FIG. 4, the pressure in the pressure line 4 is plotted as the ordinate and the volume of the pressure line is plotted as the abscissa. The higher opening pressure of the valve 5 is denoted by pj and the closing pressure is denoted by ρ. At 23, the volume »pressure diagram of a previous pressure line, for example a rigid pipe, is plotted. The branch of the curve rises very steeply in accordance with the steeply rising spring characteristic of a rigid pipe. The storage volume marked with hatching is therefore very small. At 24, the characteristic curve of an inventive external pressure line is drawn on. The curve is divided into two branches, a first gently rising branch and a second very steeply rising branch. The gentle rise corresponds roughly to the stretching of the high-pressure guinemixing hose 13 or the tension of the spring 19 at the transition point from the gently rising suna steeply rising branch of curve 24 is the point ssf-reiclvi :; at the <a, for example, the high-pressure rubber hose 13 at as? diülcärahtigena radially change the steel wire reinforcement to the plant Izornrnt or on which the 'turns of the spring 19 are placed on top of each other * The steeply rising branch then corresponds approximately to the

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hold a rigid body. Due to the very gentle rise of the first branch of the curve, the storage volume, also marked with hatching, becomes very large in the pressure line according to the invention. Since the storage volume is very large ₄ , a very long injection time is then also achieved in a desirable manner.

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Claims (1)

(P. B. 2683) /O Expectations Device for controlling valves, in particular fuel injection valves with a high-pressure pump, which is connected to the valve to be controlled via a pressure line, characterized in that the Volume of the pressure line (4) in the pressure range between the closing pressure and the opening pressure of the valve tils (5) for receiving a predetermined storage volume · » lumens can be enlarged against a spring force. Device according to Claim 1, characterized in that an elastically stretchable line is used to form the pressure line (4) High pressure rubber hose (13) is provided. Device according to Claim 2, characterized in that the high-pressure rubber hose (13) is surrounded by at least one steel wire reinforcement (14, 15). Device according to claim 3, characterized by a first, radially inner, directly on the surface of the high " pressure rubber hose (13) arranged steel wire armature tion (14) with a soft spring characteristic and a second, radially outer one with a radial distance to the first. arranged steel wire reinforcement (15) with a hard spring characteristic. V- 309884/0383 5. Apparatus according to claim 1, characterized in that a cylinder (18) is connected to the pressure line, in which a piston {20) loaded by a spring (19) is movably mounted. 6. Apparatus according to claim 1, characterized in that that with the pressure line (4) a space closed off by a membrane is in communication. ' 7. Device according to one of the preceding claims, characterized in that a at a yorbestimm « maximum pressure opening safety valve (8) is provided. 8. Device according to one of the preceding claims, characterized in that by a high pressure pump (1) several pressure lines (4) via a distribution piece (3) can be charged » 309884/0383 Blank page