GB2136051A

GB2136051A - Test device for injection systems

Info

Publication number: GB2136051A
Application number: GB08405363A
Authority: GB
Inventors: Bert Wurst
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1983-03-02
Filing date: 1984-03-01
Publication date: 1984-09-12
Also published as: JPS59160068A; GB2136051B; IT8419835A0; DE3307243C2; DE3307243A1; IT1174505B; GB8405363D0

Abstract

The test device for injection systems has a closed housing 10 filled with a compressed gas, the pressure of which corresponds, in particular, to the compression pressure of the internal combustion engine at the start of injection. Located in the bottom of the chamber 10, opposite the nozzle, is a recess 14 which has a pressure- regulating valve 16 connected after it. The test fluid is supplied via the pressure-regulating valve to a flowmeter device. The chamber 10 is put under pressure via a pump 17 and a non-return valve. The nozzle 11 is connected to an injection pump. An embodiment discloses several nozzles in a chamber, each nozzle having its own pressure regulating valve assigned to it. A further embodiment indicates a test device having a flowmeter device (31, Fig. 3, not shown) provided in the chamber. The invention provides for testing of injection systems in a manner true closely related to engine operating conditions, <IMAGE>

Description

SPECIFICATION Test device for injection systems The invention starts from a test device according to the pre-characterising clause of the main claim. In test devices of this type, two different measuring methods are used, namely an open system and a closed system. In the open system, the test fluid is sprayed from the nozzle into the open, that is to say the outer atmospheric pressure prevails in front of the test nozzle. In the closed system, the test fluid is injected into a measuring chamber which is already filled with fluid or which fills up during the measuring operation. Consequently, test fluid is located in front of the test nozzle, and not air as in the open system. The sprayed test fluid has to accelerate and displace the fluid located in front of the nozzle.

The disadvantage of both systems, therefore, is that they are not true to reality.

Advantages of the invention In contrast to these, the test device according to the invention with the characterising features of the main claim has the advantage that conditions in the internal combustion engine can be simulated in a simple way for the test operation. A test technique which is true to reality and directly related to the engine is consequently achieved.

As a result of the measures listed in the subclaims, advantageous developments and improvements of the features indicated in the main ciaim are possible. It is especially advantageous to arrange several test nozzles in the chamber or to provide in the chamber, in addition, also flowmeter devices assigned to the injection nozzles.

Drawing Exemplary embodiments of the invention are illustrated in the drawing and explained in more detail in the following description. Figure 1 shows a test device in a diagrammatic representation, Figure 2 shows a modification of the exemplary embodiment according to Figure 1 and Figure 3 shows a second exemplary embodiment.

Description of the exemplary embodiment In Figure 1, 10 denotes a closed chamber, on the top side of which is located an injection nozzle 11 directed into the chamber. This nozzle is connected to a line 12 which comes from an injection pump (not shown). A spray damper 1 3 is arranged round the mouth of the injection nozzle.

Located on the underside of the chamber 10 is a funnel-like recess 1 4 to which a pressureregulating valve 1 6 is connected via a line 1 5. The line 1 5 leads to a vessel receiving the test fluid.

The chamber 10 is filled with a compressed gas, especially air, by means of an air pump 1 7 via a line 18 having a non-return valve 19.

Appropriately, at the start of testing, the pressure is brought to a value corresponding to the compression pressure in the internal combustion engine at the start of injection. The direction of opening of the non-return valve is established from the gas pump 1 7 towards the chamber 10.

As a result of the injection of test fluid into the closed chamber at the pressure mentioned, a testing of the injection system which is true to reality and directly related to the engine is achieved, since the injection system injects into the compressed gas. In this way, conditions in the internal combustion engine can be simulated in a simple way. The test fluid can first flow via the line 15 with the built-in pressure-regulating valve 16 into a flowmeter device (not shown). This measuring device can operate continuously (for example, a displacement counter) or discontinuously (for example, measuring glasses). Weight-measuring devices can also be used.

The chamber 10 must be designed in terms of its volume in such a way that there is in its lower part a sufficiently large space for the entire measuring range, thus ensuring that the level of the test fluid never rises so high that the nozzle injects against a liquid column.

Under certain circumstances, there is no need for a separate supply of pressure via the line 18 by means of an outer air pump 1 7, if a pressure buildup process is carried out before the actual measuring operation. During this process, the injection pump conveys test fluid into the chamber 10 via the nozzle until the pressure set at the pressure-regulating valve 1 6 is reached. The fluid flowing off from the pressure-regulating valve then signals that the test or operating pressure has been reached.

The exemplary embodiment according to Figure 2 differs from that according to Figure 1 essentially in that several injection nozzles are now arranged in the chamber. The chamber is designated by 20, several nozzles being arranged on its top side in exactly the same way as in the exemplary embodiment according to Figure 1, and again a funnel-shaped recess 14 located opposite each nozzle is formed on the underside of the chamber. A pressure-regulating valve 1 6 is again connected via the line 1 5 to each such recess. The working pressure is likewise provided again in the way described above.

If pressure is supplied from outside via the line 18, the non-return valve 1 9 is necessary to ensure that the pressure conditions remain quite specific in the particular chamber subjected to the injection operation. Moreover, when several chambers are supplied in parallel from a common pressure-supply device, this prevents the pressure conditions in adjacent chambers from being influenced by injection operations in another chamber. When non-return valves are used, different pressure levels can also be established in various chambers for the purpose of special examinations. By means of the proposed test device, the gas counter pressures can be set individually for each test-nozzle chamber, and any open measuring systems can be connected after it.

The exemplary embodiment according to Figure 3 differs from the preceding embodiment essentially in that, here, each injection nozzle 10 has assigned to it a measuring system 30 which appropriately consists of a displacement counter measuring continuously. The injection quantity of each nozzle, after being sprayed out into the chamber 30 which is again under gas pressure, is introduced into the measuring system 31 after covering a specific distance. In this exemplary embodiment, the funnel-shaped recesses 1 4 are not necessary, as they are in the previous exemplary embodiments, but only one pressureregulating valve 1 6 is required for the entire device. Moreover, it has the advantage that no valves need be used between the nozzle and the measuring system.

Instead of the pressure-regulating valves, feed pumps switched on a function of pressure can also be used for all the exemplary embodiments.

Claims

1. Test device for injection systems in which the test fluid is supplied via a test-oil proportioning device especially an injection pump, and the test fluid sprayed from a nozzle passes into a chamber, characterised in that a compressed gas is located in the closed chamber at least in the mouth region of the nozzle.

2. Device according to Claim 1, characterised in that the pressure of the compressed gas corresponds to the compressing pressure in the internal combustion engine at the start of injection.

3. Device according to Claim 1 or 2, characterised in that the chamber is stressed by a pump (17) via a non-return valve (19) which can open in the direction from the pump towards the chamber.

4. Device according to one of Claims 1 to 3, characterised in that formed in the bottom of the chamber is a recess (14) which is located opposite the nozzle and to which is connected a pressureregulating valve (16), by which the test fluid is supplied to a flowmeter device.

5. Measuring device according to one of Claims 1 to 4, characterised in that several nozzles are arranged in the chamber, and in that a recess with a pressure-regulating valve is provided for each nozzle.

6. Device according to Claim 1, characterised in that located additionally in the chamber (30) is a flowmeter device (31) which is assigned to each nozzle and into which passes the pressure fluid sprayed out from the nozzle.

7. Device according to Claim 1, characterised in that even when several nozzles are used, only one pressure-regulating valve is connected to the chamber.

8. Device according to Claim 6, characterised in that the flowmeter device operates continuously.

9. Device according to Claim 8, characterised in that a displacement counter is used as a flowmeter device.

1 0. A test device for an injection system substantially as herein described with reference to Figure 1, Figure 2, or Figure 3 of the accompanying drawings.