High-pressure common rail fuel injection pump

Abstract

According to the high-pressure common-rail fuel injection pump, descending reset of the plunger is forced, a plunger reset spring is not needed, meanwhile, an oil delivery pump is omitted, two one-way valves are arranged in a low-pressure oil way, and necessary cooling and / or lubricating fuel oil is provided for the fuel injection pump. As a result, a smaller size, a higher applicable rotational speed, lower noise, in particular a lower overall cost, is achieved.

Description

Technical Field

[0001] The present invention relates to a fuel injection pump for an engine, and in particular to a high-pressure common rail fuel injection pump. Background Art

[0002] The high-pressure common rail fuel injection pump on an engine is a device responsible for pressurizing fuel and supplying high-pressure fuel to the engine. To ensure stable and sufficient fuel intake of the fuel injection pump, an additional fuel transfer pump is usually required to be provided in front of the fuel injection pump, bringing additional costs to the system.

[0003] The stroke of the plunger of the fuel injection pump for sucking fuel during its downward movement is achieved by a return spring. Due to the high operating speed of the plunger and extremely short downward movement time, the return spring is large in size and subject to harsh forces, resulting in high working noise, low maximum rotational speed, being unfavorable for miniaturization of the fuel injection pump, and high cost of the fuel injection pump.

[0004] In summary, the high-pressure common rail fuel injection pump of the prior art has deficiencies such as large size, low maximum rotational speed, high noise, and high cost. Summary of the Invention

[0005] The purpose of the present invention is to provide a high-pressure common rail fuel injection pump. By establishing a plunger forced downward device and utilizing the fuel sucking ability of the plunger itself, the fuel transfer pump is eliminated, and at the same time, the plunger return spring is eliminated, achieving the purposes of reducing the size of the fuel injection pump, increasing the maximum rotational speed, reducing noise, and reducing cost.

[0006] To achieve this purpose, the present invention adopts the following technical solutions.

[0007] The present invention provides a high-pressure common rail fuel injection pump, including a pump body, a camshaft, at least one plunger, and a high-pressure module; the plunger is arranged in the compression chamber of the high-pressure module and can reciprocate axially. An inlet valve and an outlet valve are arranged adjacent to the top of the compression chamber: under the action of the inlet spring, the inlet valve makes the fuel maintain a one-way flow tendency from the low-pressure fuel passage outside the inlet valve to the compression chamber; under the action of the outlet spring, the outlet valve makes the fuel maintain a one-way flow tendency from the compression chamber to the external high-pressure outlet.

[0008] A cylindrical eccentric wheel is arranged on the camshaft, a slider that can rotate around the axis is sleeved on the eccentric wheel, and a return pressure block is installed on the slider; the reciprocating sliding direction of the plunger is perpendicular to the axis of rotation of the slider; a push-pull foot is arranged at the bottom of the plunger, and the push-pull foot can be horizontally slidably assembled in the parallel chute between the slider and the return pressure block. The slider abuts against the sole of the push-pull foot to push the plunger upward, and the return pressure block abuts against the instep of the push-pull foot to pull the plunger downward; the plunger is restricted by the slider and the return pressure block and reciprocates as the eccentric wheel rotates.

[0009] The high-pressure common rail fuel injection pump is provided with a first one-way valve and a second one-way valve; the inlet of the first one-way valve is connected to the fuel inlet of the high-pressure common rail fuel injection pump, and the outlet is connected to the low-pressure fuel passage outside the inlet valve, maintaining the tendency of fuel to flow unidirectionally from the fuel inlet to the low-pressure fuel passage; the inlet of the second one-way valve is connected to the low-pressure fuel passage, and the outlet is connected to the transition oil passage, maintaining the tendency of fuel to flow unidirectionally from the low-pressure fuel passage to the transition oil passage.

[0010] The above structure cancels the plunger return spring and replaces it with a return pressure block that moves together with the slider, realizing the forced downward return movement of the plunger. The external low-pressure fuel is sucked into the compression chamber by the downward movement of the plunger, thereby omitting the additional fuel transfer pump. To control the amount of fuel entering the compression chamber, the high-pressure common rail fuel injection pump should be provided with an inlet metering solenoid valve. To ensure a certain amount of fuel enters the fuel injection pump to meet the cooling and / or lubrication requirements, together with the first one-way valve and the second one-way valve, the flow direction of the low-pressure fuel is limited.

[0011] Preferably, the first one-way valve is provided with a first one-way spring and a first one-way limit. The first one-way spring maintains the tendency of fuel to flow unidirectionally from the fuel inlet to the low-pressure fuel passage, and the first one-way limit restricts the maximum opening stroke of the first one-way valve within a range not exceeding 2 mm. The second one-way valve is provided with a second one-way spring and a second one-way limit. The second one-way spring maintains the tendency of fuel to flow unidirectionally from the low-pressure fuel passage to the transition oil passage, and the second one-way spring restricts the maximum opening stroke of the second one-way valve within a range not exceeding 2 mm.

[0012] The first one-way limit, the second one-way limit and the outlet limit arranged after the outlet valve are beneficial to accelerating the valve reset closing speed.

[0013] Preferably, the first one-way valve is arranged in the high-pressure module or the pump body.

[0014] Preferably, the second one-way valve is arranged in the high-pressure module or the pump body.

[0015] Preferably, the high-pressure common rail fuel injection pump is provided with a low-pressure module, and one or all of the first one-way valve, the second one-way valve, the fuel inlet and the fuel return port are integrally arranged in the low-pressure module.

[0016] Preferably, a pressure relief valve is further arranged in the low-pressure module; the pressure relief valve includes a pressure relief valve core, a pressure relief limit and a pressure relief spring; one end of the pressure relief spring presses on the pressure relief limit, and the other end presses on the pressure relief valve core to keep the pressure relief valve core in a closed tendency; the pressure relief valve includes an inlet and at least one outlet, wherein the inlet is connected to the transition oil passage, and at least one outlet is connected to the fuel return port.

[0017] Preferably, the pressure relief valve and the second one-way valve are axially connected in series as a whole, and the pressure relief limit and the second one-way limit are combined into one.

[0018] Preferably, the slider is further provided with a U-shaped belt. The two upper ends of the U-shaped belt respectively press on both sides of the reset pressing block, so that the reset pressing block is fixed on the slider and moves together with the slider; the U-shaped groove under the U-shaped belt bypasses the eccentric wheel and can rotate axially around the eccentric wheel.

[0019] Preferably, a bearing bush is arranged between the U-shaped belt and the eccentric wheel. The bearing bush is fixedly attached to the eccentric wheel, is in sliding contact with the eccentric wheel and rotates axially around the eccentric wheel.

[0020] Preferably, the plunger and the push-pull foot are separate independent components. The push-pull foot is arranged at the bottom of the plunger and abuts against each other; the push-pull foot and the plunger maintain integral up-and-down movement through a circlip inserted from the side and penetrating through.

[0021] Advantages of the present invention: The present invention provides a high-pressure common rail fuel injection pump. The downward reset of its plunger is forced, and a plunger return spring is not required. At the same time, the fuel transfer pump is cancelled, and two one-way valves are set up in the low-pressure oil circuit to provide the necessary cooling and / or lubricating fuel for the fuel injection pump. Therefore, a smaller size, a higher applicable rotational speed, a lower noise are achieved, and especially a lower comprehensive cost is achieved. Description of the drawings

[0022] Figure 1 is a schematic structural diagram of an embodiment of a high-pressure common rail fuel injection pump of the present invention.

[0023] Figure 2 is Figure 1 a three-dimensional schematic diagram of the forced downward structure of the plunger in the embodiment.

[0024] Figure 3 is a schematic structural diagram of another embodiment of a high-pressure common rail fuel injection pump of the present invention.

[0025] Figure 4 is Figure 3 a three-dimensional schematic diagram of the forced downward structure of the plunger in the embodiment.

[0026] Figure 5 is a schematic structural diagram of another embodiment of a high-pressure common rail fuel injection pump of the present invention.

[0027] Figure 6 is Figure 5 a three-dimensional exploded schematic diagram of the structure of the plunger and the push-pull foot in the embodiment.

[0028] In the figure: 1 - pump body; 2 - camshaft; 2a - eccentric wheel; 3 - slider; 3a - U-shaped belt; 3b - bearing bush; 4 - reset pressing block; 5 - plunger; 5a - push-pull foot; 5b - sole; 5c - instep; 5d - snap ring; 6 - high-pressure module; 6a - compression chamber; 6b - high-pressure oil outlet; 7 - oil outlet valve; 7a - oil outlet spring; 7b - oil outlet limit; 8 - oil inlet valve; 8a - oil inlet spring; 9 - oil inlet metering solenoid valve; 10 - oil return port; 11 - low-pressure fuel passage; 12 - first check valve; 12a - first check spring; 12b - first check limit; 13 - second check valve; 13a - second check spring; 13b - second check limit; 14 - transition oil passage; 15 - oil inlet port; 16 - pressure relief valve; 16a - pressure relief valve core; 16b - pressure relief limit; 16c - pressure relief spring; 17 - low-pressure module; 18 - cover plate. Detailed implementation manners

[0029] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It can be understood that the specific embodiments described herein are only used to explain the present invention, rather than limiting the present invention. In addition, it should be noted that for the convenience of description, only parts related to the present invention are shown in the drawings, rather than all the structures.

[0030] In the description of the present invention, unless otherwise clearly defined and limited, the terms "connected", "connected to" and "fixed" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection or an integral body; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0031] In the present invention, unless otherwise clearly defined and limited, the first feature being "above" or "below" the second feature may include the direct contact between the first and second features, or may include the situation where the first and second features are not in direct contact but in contact through other features between them. Moreover, the first feature being "above", "above" and "on the top" of the second feature includes that the first feature is directly above and obliquely above the second feature, or simply means that the horizontal height of the first feature is higher than that of the second feature. The first feature being "below", "below" and "under the bottom" of the second feature includes that the first feature is directly below and obliquely below the second feature, or simply means that the horizontal height of the first feature is lower than that of the second feature.

[0032] In the description of this embodiment, the orientation or positional relationships such as "upper", "lower", "left", and "right" are based on the orientation or positional relationships shown in the drawings. They are only for the convenience of description and simplifying the operations, rather than indicating or implying that the device or component referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present invention. In addition, the terms "first" and "second" are only used for distinction in description and have no special meaning. Embodiment 1

[0033] Figure 1 It is a schematic diagram of the structure of an embodiment of a high-pressure common rail fuel injection pump of the present invention. Figure 2 It is Figure 1 A three-dimensional schematic diagram of the plunger forced downward structure of the embodiment.

[0034] A high-pressure common rail fuel injection pump includes a pump body 1, a camshaft 2, a plunger 5, and a high-pressure module 6; the plunger 5 is arranged in the compression chamber 6a of the high-pressure module 6 and can reciprocate axially. An inlet valve 8 and an outlet valve 7 are arranged adjacent to the top of the compression chamber 6a: under the action of the inlet spring 8a, the inlet valve 8 keeps the fuel flowing unidirectionally from the low-pressure fuel passage 11 outside the inlet valve 8 to the compression chamber 6a; under the action of the outlet spring 7a, the outlet valve 7 keeps the fuel flowing unidirectionally from the compression chamber 6a to the external high-pressure outlet 6b.

[0035] A cylindrical eccentric wheel 2a is arranged on the camshaft 2. A slider 3 that can rotate around the axis is sleeved on the eccentric wheel 2a, and a return pressure block 4 is installed on the slider 3; the reciprocating sliding direction of the plunger 5 is perpendicular to the axis of rotation of the slider 3; a push-pull foot 5a is arranged at the bottom of the plunger 5, and the push-pull foot 5a is slidably assembled in the parallel chute between the slider 3 and the return pressure block 4. The slider 3 abuts against the sole 5b of the push-pull foot 5a to push the plunger 5 upward, and the return pressure block 4 abuts against the instep 5c of the push-pull foot 5a to pull the plunger 5 downward; the plunger 5 is restricted by the slider 3 and the return pressure block 4 and generates a reciprocating motion as the eccentric wheel 2a rotates.

[0036] The high-pressure common rail fuel injection pump is provided with a first one-way valve 12 and a second one-way valve 13; the inlet of the first one-way valve 13 is communicated with the inlet 15 of the high-pressure common rail fuel injection pump, and the outlet is communicated with the low-pressure fuel passage 11 outside the inlet valve 8, keeping the fuel flowing unidirectionally from the inlet 15 to the low-pressure fuel passage 11; the inlet of the second one-way valve 13 is communicated with the low-pressure fuel passage 11, and the outlet is communicated with the transition oil passage 14, keeping the fuel flowing unidirectionally from the low-pressure fuel passage 11 to the transition oil passage 14.

[0037] The fuel passes through the transition oil passage 14 to supply the fuel required for cooling and lubrication to the fuel injection pump.

[0038] The above structure cancels the plunger return spring and replaces it with a return pressure block that moves together with the slider, realizing the forced downward movement of the plunger for reset. When the plunger moves downward, low-pressure fuel from the outside is sucked into the compression chamber, thus eliminating the need for an additional fuel transfer pump. To control the amount of fuel entering the compression chamber, the high-pressure common rail fuel injection pump should be provided with an inlet metering solenoid valve 9. In this embodiment, the inlet metering solenoid valve 9 is a solenoid valve that opens when energized, that is, when the electromagnetic coil is energized, the inlet valve 8 remains open, and when de-energized, it resumes the trend of maintaining one-way flow. To ensure a certain amount of fuel enters the fuel injection pump to meet the cooling and / or lubrication requirements, a first check valve and a second check valve are added to limit the flow direction of the low-pressure fuel.

[0039] The first check valve 12 is provided with a first check spring 12a and a first check limit 12b. The first check spring 12a maintains the trend of fuel flowing unidirectionally from the inlet port 15 to the low-pressure fuel passage 11, and the first check limit 12b limits the maximum opening stroke of the first check valve 12 within a range not exceeding 2 mm. The second check valve 13 is provided with a second check spring 13a and a second check limit 13b. The second check spring 13a maintains the trend of fuel flowing unidirectionally from the low-pressure fuel passage 11 to the transition oil passage 14, and the second check spring 13a limits the maximum opening stroke of the second check valve 13 within a range not exceeding 2 mm.

[0040] The first check limit 12b, the second check limit 13b, and the outlet limit 7b provided after the outlet valve 7 are beneficial to accelerating the valve reset closing speed.

[0041] Both the first check valve 12 and the second check valve 13 are arranged in the high-pressure module 6. Embodiment 2

[0042] Figure 3 It is a schematic diagram of the structure of another embodiment of the high-pressure common rail fuel injection pump of the present invention. Figure 4 Is Figure 3 A three-dimensional schematic diagram of the plunger forced downward structure of the embodiment.

[0043] Different from the foregoing embodiment, the following differences exist in this embodiment.

[0044] The high-pressure module 6 is provided with an independent plunger sleeve 6c, which is easier to process. The plunger sleeve 6c and the high-pressure module 6 can use different materials, which is more conducive to reducing material costs.

[0045] Through Figure 4 It can be seen that the high-pressure common rail fuel injection pump includes two juxtaposed plungers 5, and each plunger 5 is equipped with a set of its own eccentric wheel 2a, slider 3, return pressure block 4, and push-pull foot 5a. The eccentric angles of the two eccentric wheels 2a on the camshaft 2 are 180 degrees out of phase with each other.

[0046] Both the first one-way valve 12 and the second one-way valve 13 are arranged in the pump body 1.

[0047] The fuel inlet metering solenoid valve 9 is a solenoid valve that opens when powered off. That is, when the electromagnetic coil is powered off, the fuel inlet valve 8 remains open, and when powered on, it resumes the tendency to maintain unidirectional flow. A cover plate 18 is provided above the fuel inlet metering solenoid valve 9 to seal the oil passage.

[0048] The slider 3 is further provided with a U-shaped belt 3a. The upper ends of both sides of the U-shaped belt 3a press on both sides of the reset pressure block 4 respectively, so that the reset pressure block 4 is fixed on the slider 3 and moves together with the slider 3; the U-shaped groove under the U-shaped belt 3a bypasses the eccentric wheel 2a and can rotate axially around the eccentric wheel 2a.

[0049] A bearing bush 3b is arranged between the U-shaped belt 3a and the eccentric wheel 2a. The bearing bush 3b is fixed in contact with the eccentric wheel 2a, slides in contact with the eccentric wheel 2a and rotates axially around the eccentric wheel 2a. Embodiment III

[0050] Figure 5 It is a schematic diagram of the structure of another embodiment of the high-pressure common rail fuel injection pump of the present invention. Figure 6 is Figure 5 A three-dimensional exploded view of the plunger and the push-pull foot structure of the embodiment.

[0051] Different from the foregoing embodiments, the following differences exist in this embodiment.

[0052] The high-pressure common rail fuel injection pump is provided with a low-pressure module 17. The first one-way valve 12, the second one-way valve 13, the fuel inlet 15 and the fuel return port 10 are all integrally arranged in the low-pressure module 17.

[0053] A pressure relief valve 16 is further arranged in the low-pressure module 17; the pressure relief valve 16 includes a pressure relief valve core 16a, a pressure relief limit 16b, and a pressure relief spring 16c; one end of the pressure relief spring 16c presses on the pressure relief limit 16b, and the other end presses on the pressure relief valve core 16a to keep the pressure relief valve core 16a in a closed tendency; the pressure relief valve 16 includes an inlet and at least one outlet. The inlet communicates with the transition oil passage 14, one of the outlets communicates with the fuel return port 10, and the other outlet communicates with the fuel inlet 15. The pressure relief valve 16 is of a two-stage opening type. It opens at a lower first-stage pressure, and the fuel flows back to the fuel tank from the fuel return port 10, taking away the heat in the fuel injection pump. It opens at a higher second-stage pressure, and the fuel returns to the fuel inlet 15 for recycling.

[0054] The pressure relief valve 16 and the second one-way valve 13 are axially connected in series as a whole, and the pressure relief limit 16b and the second one-way limit 13b are combined into one.

[0055] The plunger 5 and the push-pull foot 5a are separate and independent components. The push-pull foot 5a is arranged at the bottom of the plunger 5 and abuts against each other. The push-pull foot 5a and the plunger 5 are kept moving up and down integrally by a circlip 5d inserted and penetrated from the side.

[0056] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, rather than limitations on the implementation manners of the present invention. For those of ordinary skill in the art, various obvious changes, re-adjustments and substitutions can be made without departing from the protection scope of the present invention. It is not necessary and impossible to enumerate all the implementation manners here. Any modifications, equivalent substitutions and improvements made within the spirit and principle of the present invention shall be included in the protection scope of the claims of the present invention.

Claims

1. A high-pressure common rail fuel injection pump, characterized in that: The high-pressure common rail fuel injection pump includes a pump body (1), a camshaft (2), at least one plunger (5), and a high-pressure module (6); the plunger (5) is arranged in the compression chamber (6a) of the high-pressure module (6) and can reciprocate axially. An inlet valve (8) and an outlet valve (7) are arranged adjacent to the top of the compression chamber (6a): under the action of an inlet spring (8a), the inlet valve (8) makes the fuel maintain a tendency to flow unidirectionally from the low-pressure fuel passage (11) outside the inlet valve (8) to the compression chamber (6a); under the action of an outlet spring (7a), the outlet valve (7) makes the fuel maintain a tendency to flow unidirectionally from the compression chamber (6a) to the external high-pressure outlet (6b). A cylindrical eccentric wheel (2a) is arranged on the camshaft (2), a slider (3) that can rotate around an axis is sleeved on the eccentric wheel (2a), and a reset pressing block (4) is installed on the slider (3); the reciprocating sliding direction of the plunger (5) is perpendicular to the axis of rotation of the slider (3) around the axis; a push-pull foot (5a) is arranged at the bottom of the plunger (5), and the push-pull foot (5a) is slidably assembled in the parallel chute between the slider (3) and the reset pressing block (4). The slider (3) abuts against the sole (5b) of the push-pull foot (5a) to push the plunger (5) upward, and the reset pressing block (4) abuts against the instep (5c) of the push-pull foot (5a) to pull the plunger (5) downward; the plunger (5) is restricted by the slider (3) and the reset pressing block (4) and generates a reciprocating motion as the eccentric wheel (2a) rotates. The high-pressure common rail fuel injection pump is provided with a first check valve (12) and a second check valve (13); the inlet of the first check valve (13) is communicated with the inlet (15) of the high-pressure common rail fuel injection pump, and the outlet is communicated with the low-pressure fuel passage (11) outside the inlet valve (8), maintaining the tendency of fuel to flow unidirectionally from the inlet (15) to the low-pressure fuel passage (11); the inlet of the second check valve (13) is communicated with the low-pressure fuel passage (11), and the outlet is communicated with the transition oil passage (14), maintaining the tendency of fuel to flow unidirectionally from the low-pressure fuel passage (11) to the transition oil passage (14).

2. The high-pressure common rail fuel injection pump according to claim 1, characterized in that: The first check valve (12) is provided with a first check spring (12a) and a first check limit (12b). The first check spring (12a) maintains the tendency of fuel to flow unidirectionally from the inlet (15) to the low-pressure fuel passage (11), and the first check limit (12b) limits the maximum opening stroke of the first check valve (12) within a range not exceeding 2 mm. The second check valve (13) is provided with a second check spring (13a) and a second check limit (13b). The second check spring (13a) maintains the tendency of fuel to flow unidirectionally from the low-pressure fuel passage (11) to the transition oil passage (14), and the second check spring (13a) limits the maximum opening stroke of the second check valve (13) within a range not exceeding 2 mm.

3. The high-pressure common rail fuel injection pump according to claim 1, characterized in that: The first check valve (12) is arranged in the high-pressure module (6) or the pump body (1).

4. A high-pressure common rail fuel injection pump according to claim 1, characterized in that: The second check valve (13) is arranged in the high-pressure module (6) or the pump body (1).

5. The high-pressure common rail fuel injection pump according to claim 1, characterized in that: The high-pressure common rail fuel injection pump is provided with a low-pressure module (17); one or all of the first one-way valve (12), the second one-way valve (13), the fuel inlet (15) and the fuel return port (10) are integrally arranged in the low-pressure module (17).

6. The high-pressure common-rail fuel injection pump according to claim 5, characterized in that: A pressure relief valve (16) is further arranged in the low-pressure module (17); the pressure relief valve (16) includes a pressure relief valve core (16a), a pressure relief limit (16b), and a pressure relief spring (16c); one end of the pressure relief spring (16c) presses on the pressure relief limit (16b), and the other end presses on the pressure relief valve core (16a) to keep the pressure relief valve core (16a) in a closed tendency; the pressure relief valve (16) includes an inlet and at least one outlet, wherein the inlet communicates with the transition oil passage (14), and at least one outlet communicates with the fuel return port (10).

7. The high-pressure common rail fuel injection pump according to claim 6, characterized in that: The pressure relief valve (16) and the second one-way valve (13) are axially connected in series as a whole, and the pressure relief limit (16b) and the second one-way limit (13b) are combined as a whole.

8. A high-pressure common rail fuel injection pump according to claim 1, characterized in that: The slider (3) is further provided with a U-shaped belt (3a). The two upper ends of the U-shaped belt (3a) respectively press on both sides of the reset pressing block (4), so that the reset pressing block (4) is fixed on the slider (3) and moves together with the slider (3); the U-shaped groove under the U-shaped belt (3a) bypasses the eccentric wheel (2a) and can rotate axially around the eccentric wheel (2a).

9. The high-pressure common rail fuel injection pump according to claim 8, characterized in that: A bearing bush (3b) is arranged between the U-shaped belt (3a) and the eccentric wheel (2a). The bearing bush (3b) is fixedly attached to the eccentric wheel (2a), is in sliding contact with the eccentric wheel (2a) and rotates axially around the eccentric wheel (2a).

10. A high-pressure common rail fuel injection pump according to claim 1, characterized in that: The plunger (5) and the push-pull foot (5a) are separate independent components. The push-pull foot (5a) is arranged at the bottom of the plunger (5) and abuts against each other; the push-pull foot (5a) and the plunger (5) move up and down integrally by a circlip (5d) inserted from the side and penetrating through.

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