RU2542648C1 - Injector test and adjustment bench - Google Patents

Abstract

FIELD: engines and pumps.

SUBSTANCE: invention proposes an injector test and adjustment bench containing counter pressure device (8) allowing to create variable counter pressure to fuel injector, which varies similar to pressure of gases in an engine cylinder during injection, which differs by the fact that the counter pressure device consists of two plungers (10, 11), adjustment sleeves (12, 13) with counter pressure springs (14, 15) and bypass valve (19).

EFFECT: cheaper and simpler design of a bench.

2 dwg

Description

The invention relates to the field of testing and adjusting fuel equipment of diesel internal combustion engines.

A known bench for testing and adjusting nozzles, including interconnected injection chamber, pump element and fuel line with pressure gauge [1].

The disadvantage of this stand is the lack of accuracy of the controlled parameters due to the lack of back pressure for fuel injection, equal to the pressure in the combustion chamber of a diesel engine during the fuel injection period.

A known method for quantifying the quality of atomization of fuel by a nozzle and a device for its implementation with a transparent container in which a predetermined backpressure for injection by a gas-liquid gearbox is automatically supported [2].

A device for measuring the cyclic fuel supply, made in the form of an injection chamber connected to the measuring chamber, a plunger associated with the measuring sensor, a sub-plunger cavity and a pressure regulator for creating and regulating the back pressure from the sub-plunger side in the measuring chamber, is equivalent to the average pressure in the engine combustion chamber during the fuel injection period [3].

A common disadvantage of the method [2] and device [3] is the inability to simulate the variable gas pressure generated by the piston in the diesel cylinder during its movement during fuel injection, which significantly distorts the test results.

The closest technical solution to the claimed invention is a bench for testing a fuel injection system of a diesel engine, comprising a backpressure device equipped with a mechanism for synchronizing with the injection process of controlling the amount of back pressure, comprising a master and a pressure sensor of the working fluid, a unit for comparing their signals, an amplifier for the summing signal from the comparator and a throttle working fluid driven by an electric motor [4]. The amount of back pressure in the injection chamber changes similarly to the change in pressure in the cylinder of a running diesel engine.

The disadvantage of this stand is the complexity of the design of the backpressure device due to the presence of a comparison unit with the amplifier of the summing signal and the throttle of the working fluid driven by an electric motor, which in turn leads to an increase in cost, metal consumption of the stand and high energy consumption.

The aim of the invention is to simplify the design of the stand.

This goal is achieved by the fact that the stand is equipped with a back pressure device, consisting of two plungers, adjusting clips with back pressure springs and an overflow valve.

Figure 1 presents a diagram of the stand.

Figure 2 presents a detailed diagram of the pressure change in the combustion chamber of a diesel engine: P _g - gas pressure, C _CR - total spring stiffness, α - angle of rotation of the crankshaft, φ - injection duration, x - spring travel, bm . - top dead center, P _n - gas pressure at the beginning of fuel injection, P _to - gas pressure at the end of fuel injection.

The stand consists of a lever 1 (Fig. 1), a pump element 2 with a discharge valve 4, a fuel tank 3 with a fuel filter 9, a nozzle 7, a back pressure device 8, pressure gauges 5 and 6 and fuel lines 20, 21 and 22. The back pressure device 8 allows create a variable counter-pressure injection of fuel, changing similarly to the gas pressure in the cylinder of a real engine during the injection process, consisting of plungers 10 and 11, adjusting clips 12 and 13 with counter-pressure springs 14 and 15 and bypass valve 19.

The stand works as follows.

When acting on the lever 1, the fuel from the fuel tank 3 passing through the fuel filter 9 through the fuel line 22 enters the pump element 2 and through the discharge valve 4 with a shut-off belt is injected into the nozzle 7 through the fuel pipe 20. The fuel is injected into the cavity 17 of the backpressure device 8 when achievement of a controlled injection start pressure, controlled by a manometer 5. Pressure increasing as the fuel is injected moves the plungers 10 and 11, compressing the counter-pressure springs 14 and 15. The stiffness and preload of the springs 14 and 15 is regulated so that the pattern of pressure change in the cavity 17, as the plungers 10 and 11 move, is as close as possible to the pattern of pressure change in the combustion chamber of a diesel engine (section 1-2 of FIG. 2). Since the surface area of the plunger 10, which is affected by the fuel pressure, is larger than the area of the passage through which the fuel pressure acts on the plunger 11, the channel 16 is in the closed state.

When the injection is stopped, the discharge valve 4 with a shut-off belt, closing, cuts off the fuel supply and sharply reduces the pressure in the fuel line 20. The plunger 10 slows down and stops, and the inertial plunger 11, spring-loaded with a less rigid spring 15, opens the channel 16. Fuel from the cavity 17, which is under pressure P _k (FIG. 2), through the channel 16 begins to flow into the cavity 18, the pressure in which is set by the bypass valve 19 and is equal to the start pressure of the next injection in the engine cylinder R _n (FIG. 2). At the end of the drain and reduce the pressure to a value of P _n (figure 2), the channel 16 is closed, ensuring the stand is ready for the next injection. The preliminary tightening of the back pressure springs 14 and 15 are regulated by adjusting clips 12 and 13, which allows you to change the amount of back pressure of the fuel injection based on the characteristics of a particular diesel engine.

The change in gas pressure in the engine cylinder during injection in section 1, 2 (Fig. 2), with an increase in the angle of rotation of the crankshaft α, is linear. When compressing the back pressure springs 14 and 15, with an increase in their travel x (Fig.2), their rigidity also increases in a linear manner. Thus, the amount of back pressure in the injection chamber changes similarly to the change in pressure in the cylinder of a running diesel engine.

The selection of back pressure springs 14 and 15 with different stiffness allows you to increase the range of back pressure and, as a result, the range of adjustable fuel systems, providing the desired nature of the pressure changes in the cavity 17 of the back pressure device 8 (section 1-2 of figure 2). The change in pressure of the cavity 17 of the backpressure device 8 is controlled by a pressure gauge 6.

The effectiveness of this stand is determined by the cost reduction and simplification of the design due to the exclusion from the circuit of the comparison unit with the amplifier of the summing signal and the throttle of the working fluid driven by an electric motor, which in turn leads to high energy costs.

Information sources

1. Patent No. 2160847, F02M 65/00. Stand for testing and adjusting nozzles. M.M. Makarov, G.N. Savosin. Declared May 6, 1999, published December 20, 2000.

2. Patent No. 2016217, F02M 65/00. A method for quantifying the quality of fuel atomization by a nozzle and a device for its implementation. Moscow Automotive Institute. Announced on 01/31/1992, published on 07/15/1994.

3. Patent No. 2059870, F02M65 / 00. Device for measuring cyclic fuel supply. Bashkir State Agrarian University. Declared August 10, 1993, published May 10, 1996.

4. Patent No. 920247, F02M 65/00. Stand for the study of diesel fuel injection system. A.A. Moldavsky, O.L. Pashkin. Declared 07/31/79, published 04/15/82.

Claims (1)

A bench for testing and adjusting nozzles containing a backpressure device that allows you to create a variable backpressure of the fuel injection, changing similarly to the gas pressure in the engine cylinder during the injection process, characterized in that the backpressure device consists of two plungers, adjusting clips with back pressure springs and an overflow valve.

Images