A low-inertia fuel injector with a quick-closing valve

Abstract

The present invention discloses a low-inertia fuel injector for a quick-closing valve, which comprises an injector body (1), an electromagnet component (2), a control valve seat (3), a needle valve body (4), and a needle valve pair (5) installed in the needle valve body; characterized in that: an intermediate valve (6) is arranged between the needle valve pair (5) and the control valve seat (3), and the intermediate valve (6) divides the control chamber B into upper and lower parts, namely a lower control chamber (B1) composed of the intermediate valve (6) and the needle valve sleeve (5b), and an upper control chamber (B2) composed of the control valve seat (3) and the valve seat (6a) of the intermediate valve (6). The fuel injector of this patent application can achieve an injection law of "first slow and then fast". When the solenoid valve is not opened, there is no static fuel leakage. After the solenoid valve is opened, the dynamic fuel leakage is also much smaller than that of the prior art.

Description

Technical Field

[0001] The invention belongs to the technical field of oil supply systems for internal combustion engines, and in particular relates to a low-inertia fuel injector with a quick closing valve of a common rail fuel injection system. Background Art

[0002] If the internal combustion engine wants to further improve thermal efficiency and reduce power loss, it needs to upgrade the injector technology from a structure with high-pressure static fuel leakage in the gap between the mating parts to a structure without high-pressure static leakage.

[0003] A fuel injector without static leakage usually has only one needle valve pair, with a high-pressure chamber and a control chamber at both ends of the pair.

[0004] This type of injector has a disadvantage, that is, the needle valve rises faster when it is opened, and falls slower when it is seated, which results in the injection pattern being fast at first and slow later, which is exactly the opposite of the ideal injection pattern of "slow at first and fast later".

[0005] The common structure of a low inertia injector without static leakage is as follows: Figure 5 and Figure 6 shown.

[0006] At the lower end of the injector body 1, a high-pressure oil inlet passage 1a and an electromagnet mounting hole 1b are arranged in parallel. The electromagnet component 2 is placed in this hole 1b; the control valve seat 3 is arranged between the injector body 1 and the needle valve body 4; the eccentrically arranged throttle hole Z is coaxial with the armature rod of the electromagnet component to form a switch valve; when the electromagnet is energized, the valve opens, and the fuel leaks into the low-pressure chamber through the throttle hole Z; the needle valve pair 5 is arranged in the needle valve body 4 and is guided by the inner hole at the lower end of the needle valve body; the internal space at the upper end of the needle valve pair 5 corresponds to the lower end surface of the control valve seat 3 to form a control chamber B; the outer part of the needle valve pair 5 and the annular space inside the needle valve body 4 form a pressure storage volume chamber A, which is connected to the high-pressure oil inlet hole 1a of the injector body through the oil passage hole 3b of the control valve seat; a throttle hole X is arranged on the upper end of the needle valve sleeve 5b of the needle valve pair 5 to connect the pressure storage volume chamber A with the control chamber B; the control chamber B is connected to the oil outlet throttle hole Z through the control valve seat oil passage hole 3a.

[0007] When the solenoid valve is opened, in order to reduce the rising speed of the needle valve 5a, the pressure drop speed of the control chamber B must be slowed down, which requires that the aperture and flow rate of the oil outlet throttling hole Z be as small as possible.

[0008] Obviously, the oil inlet throttling hole X≤the oil outlet throttling hole Z, and the reduction of Z leads to a smaller X.

[0009] As a result, when the solenoid valve is closed and the needle valve is about to move downward to close, the fuel flow rate from the pressure accumulation chamber A to the control chamber B through the throttle X is relatively small, resulting in a relatively slow pressure rise in the control chamber B and a slow seating of the needle valve. Summary of the Invention

[0010] In view of the problems existing in the prior art, the present invention provides a low-inertia injector with a quick-closing valve for a common-rail fuel injection system.

[0011] The present invention is implemented as follows. A low-inertia injector with a quick-closing valve includes an injector body (1), an electromagnet member (2), a control valve seat (3), a needle valve body (4), and a needle valve pair (5) installed in the needle valve body. A high-pressure fuel inlet passage (1a) and an electromagnet mounting hole (1b) are arranged in parallel on the injector body (1). The needle valve pair (5) is arranged in the needle valve body (4). The needle valve pair (5) includes a needle valve (5a) and a needle valve sleeve (5b). The needle valve (5a) is inserted into the guiding hole at the lower end of the needle valve body. The lower end face of the needle valve sleeve (5b) of the needle valve pair (5) and the control valve seat (3) correspondingly form a control chamber B. The annular space between the outside of the needle valve pair (5) and the inside of the needle valve body (4) forms a pressure accumulation volume chamber (A), which is connected to the high-pressure fuel inlet hole (1a) of the injector body through the oil passage hole (3b) of the control valve seat. It is characterized in that: An intermediate valve (6) is arranged between the needle valve pair (5) and the control valve seat (3). The intermediate valve includes an intermediate valve seat (6a) and a valve core (6b). The valve core is slidably and sealingly installed in the valve seat. The intermediate valve (6) divides the control chamber B into upper and lower parts, namely a lower control chamber (B1) formed by the intermediate valve (6) and the needle valve sleeve (5b), and an upper control chamber (B2) formed by the control valve seat (3) and the valve seat (6a) of the intermediate valve (6). An intermediate valve oil outlet throttle hole (Y) for connecting the lower control chamber B1 and the upper control chamber B2 is provided on the valve seat (6a). An intermediate valve oil inlet throttle hole X is provided on the valve seat (6a) of the intermediate valve (6) to connect the pressure accumulation volume chamber (A) and the control chamber (B). The upper control chamber (B2) is connected to the control valve seat oil outlet throttle hole (Z) of the control valve seat (3) through the control valve seat oil passage hole (3a). The intermediate valve oil inlet throttle hole (X) ≤ the control valve seat oil outlet throttle hole (Z); The intermediate valve oil inlet throttle hole (X) > the intermediate valve oil outlet throttle hole (Y).

[0012] Preferably, between the valve sleeve of the intermediate valve and the needle valve sleeve of the needle valve pair (5), there is an annular positioning connection sleeve (7).

[0013] Preferably, an interference fit is adopted between the outer circle of the needle valve sleeve (5b) and the inner circle of the annular positioning connection sleeve (7), and a clearance fit is adopted between the outer circle of the intermediate valve seat (6a) and the inner circle of the annular positioning connection sleeve (7).

[0014] Preferably, there is an angular difference between the lower sealing conical surface of the valve seat (6a) of the intermediate valve and the sealing conical surface of the valve core (6b), and the valve seat (6a) and the valve core (6b) form a double conical surface valve (62).

[0015] Preferably, the angular difference is 0.5°-1.5°.

[0016] Preferably, a hole (5a1) is provided at the upper end of the needle valve body, and a spring (8) is arranged in the hole (5a1). The lower end of the spring is supported on the bottom of the hole (5a1), and the upper end of the spring abuts against the lower end surface of the valve core (6b).

[0017] Preferably, the value range of the oil inlet throttle hole (X) is between 0.1 and 0.2 mm.

[0018] Advantages and technical effects of the present invention: The injector of this patent application can achieve the fuel injection law of "slow first and then fast". When the solenoid valve is not opened, there is no static fuel leakage. After the solenoid valve is opened, the dynamic fuel leakage is also much smaller than that of the prior art. Description of the Drawings

[0019] Figure 1 It is the assembly drawing of the injector assembly of this application;

[0020] Figure 2 It is the enlarged view of the control part of the injector of this application;

[0021] Figure 3 It is the schematic diagram of the opening control oil circuit of this application;

[0022] Figure 4 It is the schematic diagram of the closing control oil circuit of this application;

[0023] Figure 5 It is the schematic diagram of the prior art structure;

[0024] Figure 6 It is the control oil circuit diagram of the prior art;

[0025] Figure 7 It is the comparison diagram of the fuel injection laws of the two injectors of the present invention and the prior art. Detailed Description of the Invention

[0026] In order to make the purpose, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0027] Please refer to Figures 1 to 4A low-inertia fuel injector with a fast closing valve comprises a fuel injector body 1, an electromagnet component 2, a control valve seat 3, a needle valve body 4, and a needle valve pair 5 installed in the needle valve body; the fuel injector body 1 is provided with a high-pressure oil inlet passage 1a and an electromagnet installation hole 1b arranged in parallel; the needle valve pair 5 is arranged in the needle valve body 4, the needle valve pair 5 comprises a needle valve 5a and a needle valve sleeve 5b, and the needle valve 5a is inserted into a guide hole at the lower end of the needle valve body; the needle valve sleeve 5b of the needle valve pair 5 corresponds to the lower end surface of the control valve seat 3 to form a control chamber B; the outer portion of the needle valve pair 5 and the annular space inside the needle valve body 4 form a pressure storage volume chamber A, which is connected to the high-pressure oil inlet hole 1a of the fuel injector body through the oil passage hole 3b of the control valve seat;

[0028] The inventive point of the present invention is that an intermediate valve 6 is arranged between the needle valve pair 5 and the control valve seat 3, the intermediate valve includes an intermediate valve seat 6a and a valve core 6b, and the valve core is slidingly sealed and installed in the valve seat; the intermediate valve 6 divides the control chamber B into two parts, namely, the control chamber lower chamber B1 composed of the intermediate valve 6 and the needle valve sleeve 5b, and the control chamber upper chamber B2 composed of the control valve seat 3 and the valve seat 6a of the intermediate valve 6; the valve seat 6a is provided with an intermediate valve oil outlet throttling hole Y connecting the control chamber lower chamber B1 and the control chamber upper chamber B2; the valve seat 6a of the intermediate valve 6 is provided with an intermediate valve oil inlet throttling hole X, which connects the pressure storage volume chamber A with the control chamber B; the control chamber upper chamber B2 is connected with the control valve seat oil outlet throttling hole Z of the control valve seat 3 through the control valve seat oil passage hole 3a;

[0029] The intermediate valve oil inlet throttling hole X is less than or equal to the control valve seat oil outlet throttling hole Z; the intermediate valve oil inlet throttling hole X is greater than the intermediate valve oil outlet throttling hole Y.

[0030] Preferably, an annular positioning connection sleeve 7 is provided between the valve sleeve of the intermediate valve and the needle valve sleeve of the needle valve pair 5 .

[0031] Preferably, the outer circle of the needle valve sleeve 5b and the inner circle of the annular positioning connecting sleeve 7 are transitionally matched, and the outer circle of the intermediate valve seat 6a and the inner circle of the annular positioning connecting sleeve 7 are clearance matched.

[0032] Preferably, an angle difference is provided between the lower sealing cone surface of the valve seat 6a of the intermediate valve and the sealing cone surface of the valve core 6b, and the valve seat 6a and the valve core 6b form a double cone valve 62. In order to ensure the flow area when the valve core is opened and the smaller impact force when the seat is seated, the angle difference of the two cone surfaces is set in a smaller range, preferably, the angle difference is 0.5°-1.5°.

[0033] Preferably, in order to ensure that the valve core 6b is quickly and reliably seated, a hole 5a1 is provided at the upper end of the needle valve body, and a spring 8 is arranged in the hole 5a1. The lower end of the spring is supported on the bottom of the hole 5a1, and the upper end of the spring abuts against the lower end surface of the valve core 6b.

[0034] When the needle valve is lifted and begins to spray oil after the solenoid valve is energized, the speed of change of the hydraulic force applied to the top of the needle valve, i.e., the speed of change of the pressure in the lower chamber B1 of the control chamber, is very slow compared to the ordinary structure. This is due to the smaller diameter of the intermediate valve oil outlet throttling hole Y, such as <0.1mm; and the slower pressure change speed of the upper chamber B2 of the control chamber. The upper chamber B2 of the control chamber can have a slower pressure drop speed after the solenoid valve is energized, which depends on the smaller diameter of the control valve seat oil outlet throttling hole Z, such as <0.2mm; and the replenishment of fuel from the pressure accumulator chamber A to the upper chamber B2 of the control chamber through the oil inlet throttling hole X. Obviously, in the process of spraying oil after the solenoid valve is opened, it is required that the intermediate valve oil inlet throttling hole X ≤ the control valve seat oil outlet throttling hole Z.

[0035] When the solenoid valve is powered off and needs to end the injection, the oil outlet throttle hole Z is closed. At this time, the pressure rise rate of the upper chamber B2 of the control chamber is greater than the pressure rise rate of the lower chamber B1 of the control chamber, and the pressure of the upper chamber B2 of the control chamber is greater than the pressure of the lower chamber B1 of the control chamber. In order to increase the pressure difference between the two volume chambers and enable the intermediate valve core 6b to open quickly and reliably, the intermediate valve oil inlet throttle hole X is required to be greater than the intermediate valve oil outlet throttle hole Y. Therefore, the value range of the oil inlet throttle hole X is between 0.1 and 0.2 mm.

[0036] When the valve core 6b is opened, the fuel in the pressure accumulation volume chamber A flows into the control chamber lower chamber B1 through the oil hole 6a1 of the valve seat 6a and the oil path 63 formed by the annular space of the valve core 6b, through the valve port 62. This causes the pressure in the control chamber lower chamber B1 to rise rapidly in an instant, that is, the hydraulic force at the top of the needle valve rises rapidly, and the needle valve quickly seats.

[0037] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A low-inertia fuel injector with a quick-closing valve, comprising an injector body (1), an electromagnet component (2), a control valve seat (3), a nozzle body (4), and a nozzle pair (5) installed in the nozzle body; a high-pressure fuel inlet passage (1a) and an electromagnet mounting hole (1b) are arranged in parallel on the injector body (1); the nozzle pair (5) is arranged in the nozzle body (4), the nozzle pair (5) includes a nozzle needle (5a) and a nozzle sleeve (5b), and the nozzle needle (5a) is inserted into the guiding hole at the lower end of the nozzle body; the nozzle sleeve (5b) of the nozzle pair (5) and the lower end face of the control valve seat (3) correspondingly form a control chamber B; the outer part of the nozzle pair (5) and the annular space inside the nozzle body (4) form a pressure accumulation volume chamber (A), which is connected to the high-pressure fuel inlet passage (1a) of the injector body through the oil passage hole (3b) of the control valve seat; it is characterized in that: An intermediate valve (6) is arranged between the needle valve pair (5) and the control valve seat (3). The intermediate valve includes an intermediate valve seat (6a) and a valve core (6b). The valve core is slidably and sealingly installed in the intermediate valve seat. The intermediate valve (6) divides the control chamber B into upper and lower parts, namely a lower control chamber (B1) composed of the intermediate valve (6) and the needle valve sleeve (5b), and an upper control chamber (B2) composed of the control valve seat (3) and the intermediate valve seat (6a) of the intermediate valve (6). An intermediate valve oil outlet throttle hole (Y) communicating the lower control chamber B1 with the upper control chamber B2 is provided on the intermediate valve seat (6a). An intermediate valve oil inlet throttle hole X is provided on the intermediate valve seat (6a) of the intermediate valve (6) to communicate the accumulator volume chamber (A) with the control chamber (B). The upper control chamber (B2) is communicated with the control valve seat oil outlet throttle hole (Z) of the control valve seat (3) through the control valve seat oil passage hole (3a). The intermediate valve oil inlet throttle hole (X) ≤ the control valve seat oil outlet throttle hole (Z); the intermediate valve oil inlet throttle hole (X) > the intermediate valve oil outlet throttle hole (Y). An angle difference is provided between the lower sealing cone surface of the intermediate valve seat (6a) and the sealing cone surface of the valve core (6b). The intermediate valve seat (6a) and the valve core (6b) form a double-cone surface valve (62). The angle difference is 0.5° - 1.5°. A hole (5a1) is provided at the upper end of the needle valve body. A spring (8) is arranged in the hole (5a1). The lower end of the spring is supported on the bottom of the hole (5a1), and the upper end of the spring abuts against the lower end surface of the valve core (6b).

2. The low-inertia fuel injector of the quick-closing valve according to claim 1, characterized in that: Between the valve sleeve of the intermediate valve and the needle valve sleeve of the needle valve pair (5), there is an annular positioning connection sleeve (7).

3. The low-inertia fuel injector of the quick-closing valve according to claim 1, characterized in that: The outer circle of the needle valve sleeve (5b) and the inner circle of the annular positioning connection sleeve (7) adopt an interference fit, and the outer circle of the intermediate valve seat (6a) of the intermediate valve and the inner circle of the annular positioning connection sleeve (7) adopt a clearance fit.

4. The low-inertia fuel injector of the quick-closing valve according to claim 1, characterized in that: The value range of the oil inlet throttle hole (X) is between 0.1 and 0.2 mm.

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