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(11) | EP 3 301 296 A1 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | PRESSURE CONTROL VALVE ASSEMBLY AND FUEL INJECTION DEVICE |
| (57) A pressure control valve assembly (27) comprises a housing (23), a valve seat (45)
formed by the housing and defining a concave (53), a throttling passage (55) formed
in the housing and establishing a communication between a pressure control chamber
(31) with the concave, a return passage (61) formed in the housing and communicating
with the concave, a driving rod (47) movable longitudinally in the housing, a sealing
cone (49) attached to the driving rod for closing or opening the throttling passage.
The sealing cone comprises a sealing head (49b) including first and second truncated
parts (49c,49d) connected together, an annular line is formed between first and second
truncated parts, and the sealing cone forms a sealing contact with a surface of the
concave at the annular line. The present invention prevents cavitation erosion or
particle wear on the valve seat area.
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TECHNICAL FIELD
[0001] The present utility model relates to injecting fuel into a combustion chamber of an internal combustion engine, and more particularly, to a pressure control valve assembly for fuel injection devices and a fuel injection device comprising the same.
BACKGROUND
[0002] Fuel injection devices for injecting fuel directly into a combustion chamber of an internal combustion engine have been disclosed. A fuel injection device typically comprises a needle valve assembly and a pressure control valve assembly for controlling opening and closing of the needle valve assembly. The pressure control valve assembly renders a needle valve element of the needle valve assembly to move so as to open or close an injection hole of the needle valve assembly by controlling pressure within a pressure control chamber defined by the needle valve element and a housing of the needle valve assembly.
[0003] Fig.1 schematically shows a portion of a conventional pressure control valve assembly for controlling opening and closing of a needle valve assembly. As shown in Fig.l, the conventional pressure control valve assembly 1 generally comprises a valve seat 3 defined by a part of a housing, a ball seat 7 attached to a driving rod 5, and a sealing ball 9 disposed on the ball seat 7. A throttling passage 11 communicating with a pressure control chamber (not shown) defined by a needle valve element and a housing of a needle valve assembly is formed in the housing defining the valve seat 3. The sealing ball 9 is used to open or occlude the throttling passage 11. As the driving rod 5 is moved downward to render the sealing ball 9 to abut against the valve seat 3 and occlude the throttling passage 11, the pressure within the pressure control chamber increases under the action of high-pressure fuel from a high-pressure fuel inlet, such that the needle valve element of the needle valve assembly is moved to close an injection hole of the needle valve assembly to stop fuel injection. As the driving rod 5 is moved upward to render the sealing ball 9 to move away from the valve seat 3 and open the throttling passage 11, the high-pressure fuel in the pressure control chamber is discharged through the throttling passage 11, such that the pressure within the pressure control chamber decreases and the needle valve element of the needle valve assembly is moved in the opposite direction to open the injection hole of the needle valve assembly, thereby injecting the fuel into a combustion chamber.
[0004] The pressure control chamber defined by the needle valve element and the housing of the needle valve assembly is typically at a high pressure such as 1600 bar to 2000 bar, while the pressure control valve assembly at the other end of the throttling passage 11 is typically at a low pressure such as atmospheric pressure. Such a great pressure difference causes the high-pressure fuel discharged through the throttling passage 11 to vaporize and generate steam when the high-pressure fuel in the pressure control chamber is discharged through the throttling passage 11. The impact force, which is produced as bubbles formed by the steam burst, will contribute to cavitation erosion and particle wear at a valve seat area around the throttling passage, resulting in untight sealing of the sealing ball against the throttling passage when abutting against the valve seat, affecting normal operation of the fuel injection device.
[0005] Therefore, there is a need to improve the conventional pressure control valve assembly for fuel injection devices.
SUMMARY
[0006] An object of the present utility model is to provide a pressure control valve assembly for fuel injection devices and a fuel injection device comprising the same. The pressure control valve assembly is capable of reducing or eliminating cavitation erosion and particle wear created by an impact force produced as bubbles formed by discharging high-pressure fuel through a throttling passage burst to a valve seat area around the throttling passage, ensuring sealing effect when the throttling passage is occluded.
[0007] According to an aspect of the present utility model, a pressure control valve assembly is provided, comprising:
a housing;
a valve seat formed by a part of the housing and defining a conical concave;
a throttling passage formed in the housing and communicating a pressure control chamber with the concave;
a return passage formed in the housing and communicating with the concave;
a driving rod movable longitudinally in the housing;
a sealing cone attached to the driving rod so as to move with the driving rod, the sealing cone being capable of abutting against a surface of the concave to occlude the throttling passage or moving away from the surface of the concave to open the throttling passage;
an actuating means for actuating the driving rod so as to move the sealing cone away from the surface of the concave; and
a spring acting on the driving rod so as to render the sealing cone to abut against the surface of the concave;
wherein the sealing cone comprises a sealing head including a first truncated part adjacent to the driving rod and a second truncated or conical part connecting with the first truncated part, an annular line is formed between the first truncated part and the second truncated or conical part, and the sealing cone forms a sealing contact with the surface of the concave at the annular line.
[0008] According to another aspect of the present utility model, a fuel injection device is provided, comprising:
a pressure control valve assembly as described above; and
a needle valve assembly;
wherein the needle valve assembly opens to inject the fuel or closes to stop injecting the fuel according to changes in pressure within the pressure control chamber.
[0009] According to the present utility model, since the sealing cone forms the sealing contact with the surface of the concave at the annular line, a space gap defined by the valve seat and the sealing head of the sealing cone to allow the high-pressure fuel to pass through is changed by changing angle formed by a generatrix of the first truncated part and/or a generatrix of the second truncated or conical part with respect to the surface of the conical concave to change flow state and flow direction of the high-pressure fuel, without changing the contact position of the sealing cone with the surface of the concave, such that the cavitation erosion and particle wear created by the impact force produced as the bubbles formed by the high-pressure fuel steam burst to the valve seat area around the throttling passage are ultimately reduced or eliminated, ensuring reliable sealing against the throttling passage and thereby ensuring that the fuel injection device operates normally.
BRIEF DESCRIPTION OF DRAWINGS
[0010] In the drawings:
FIG. 1 schematically shows a portion of a conventional pressure control valve assembly for controlling opening and closing of a needle valve assembly;
FIG. 2 is a schematic sectional view of a fuel injection device according to the present utility model; and
FIG. 3 schematically shows a portion of a pressure control valve assembly for controlling opening and closing of a needle valve assembly according to the present utility model.
[0011] Certain components known in the art are omitted or simplified in the drawings for the purpose of clearly illustrating and understanding the present utility model.
DETAILED DESCRIPTION OF THE UTILITY MODEL
[0012] Detailed descriptions of preferred embodiments of the present utility model will be described in detail below in conjunction with examples. It will be understood by those skilled in the art that these exemplary embodiments are not meant to impose any limitation on the present utility model.
[0013] Fig. 2 is a schematic sectional view of a fuel injection device according to the present utility model and Fig. 3 schematically shows a portion of a pressure control valve assembly for controlling opening and closing of a needle valve assembly according to the present utility model. As shown in Fig. 2 and Fig. 3, the fuel injection device 21 according to the present utility model generally comprises a housing 23, a needle valve assembly 25 disposed in the housing 23 and a pressure control valve assembly 27 disposed in the housing 23 for controlling opening and closing of the needle valve assembly 25. For simplicity, the housing 23 is formed as an integral body in the drawings, but it is to be understood that the housing 23 may be composed of a plurality of parts for ease of manufacture and assembly.
[0014] The needle valve assembly 25 generally includes a needle valve element 29 disposed in the housing 23 and movable in a longitudinal direction. As known in the art, a part (upper part in Fig. 2) 29a of the needle valve element 29 is in a substantially cylindrical shape with a larger diameter, while the other part (lower part in Fig. 2) 29b of the needle valve element 29 is in a substantially cylindrical shape with a smaller diameter and has a conical tip 29c. A pressure control chamber 31 is defined in the housing 23 by an end of the part 29a of the needle valve element 29 together with the housing 23. The volume of the pressure control chamber 31 may increase as the needle valve element 29 is moved downward in the longitudinal direction or decrease as the needle valve element is moved upward in the longitudinal direction. A nozzle pressure chamber 33 surrounding the other part 29b of the needle valve element 29 is defined by the housing 23 at the periphery of the other part 29b of the needle valve element 29 and a nozzle hole 35 is formed in an end (lower end of the housing 23 in Fig. 2) of the nozzle pressure chamber 33. The conical tip 29c of the needle valve element 29 may abut against the nozzle hole 35 so as to occlude the nozzle hole 35 when the needle valve element 29 is moved downward in the longitudinal direction; and the conical tip 29c of the needle valve element 29 may move away from the nozzle hole 35 so as to open the nozzle hole 35 when the needle valve element 29 is moved upward in the longitudinal direction. A spring 37 is disposed on the needle valve element 29. The spring 37 always tends to press the conical tip 29c of the needle valve element 29 against the nozzle hole 35. A first fluid passage 41 communicating the pressure control chamber 31 with a high-pressure fuel inlet 39 and a second passage 43 communicating the nozzle pressure chamber 33 with the high-pressure fuel inlet 39 are also formed in the housing 23.
[0015] The pressure control valve assembly 27 generally comprises a valve seat 45 formed by a part of the housing 23, a driving rod 47 movable longitudinally in the housing 23, a sealing cone 49 attached to the driving rod 47 so as to move with the driving rod 47, and an actuating means 51 for actuating the driving rod 47. The valve seat 45 defines a substantially conical concave 53 and a throttling passage 55 communicating the pressure control chamber 31 with the concave 53 is also formed in the housing 23. The sealing cone 49 includes a main body part 49a which is exemplified as being cylindrical and a conical sealing head 49b. Of course, it is also possible to omit the main body part 49a. The sealing head 49b includes a first truncated part 49c connecting with main body part 49a and a second truncated or conical part 49d connecting with the first truncated part 49c. Since the angle formed by a generatrix of the first truncated part 49c with respect to a surface of the conical concave 53 is different from the angle formed by a generatrix of the second truncated or conical part 49d with respect to the surface of the conical concave 53, an annular line is formed between the first truncated part 49c and the second truncated or conical part 49d. The sealing head 49b forms tight sealing contact with the valve seat 45 just at the annular line when the sealing head 49b abuts against the valve seat 45, thereby occluding or closing the throttling passage 55.
[0016] The actuating means 51 for actuating the driving rod 47 may be pneumatic or hydraulic actuating means. In a preferred embodiment, the actuating means 51 is shown as an electromagnetic coil communicating with a power supply (not shown) through a wire 57, while the driving rod 47 is made of a magnetic material capable of being attracted by electromagnetic force generated by the electromagnetic coil. A spring 59 acting on the driving rod 47 is also disposed in the housing 23 and the spring 59 always tends to urge the driving rod 47 to move toward the valve seat 45 so as to press the sealing head 49b of the sealing cone 49 against the valve seat 45, thereby occluding or closing the throttling passage 55. A return passage 61 for communicating the concave 53 with an external low-pressure circuit (not shown) is also formed in the housing 23. In order to ensure that the driving rod 47 is moved in a proper direction, a guide partition 63 through which the driving rod 47 passes may be disposed above the concave 53 and a through hole 65 formed in the guide partition 63 communicates the concave 53 with the return passage 61.
[0017] The operation of the fuel injection device according to the present utility model will be described in detail below in conjunction with Fig. 2.
[0018] Initially, the electromagnetic coil 51 is not energized and no electromagnetic attracting force is applied to the driving rod 47 made of the magnetic material. The driving rod 47 is urged to move toward the valve seat 45 under the urging force exerted by the spring 59 disposed at the upper end of the driving rod 47, such that the sealing head 49b of the sealing cone 49 attached to the driving rod 47 is pressed against the valve seat 45, thereby occluding or closing the throttling passage 55. At this time, the pressure control chamber 31 communicates with the high-pressure fuel inlet 39 through the first fluid passage 41, and the nozzle pressure chamber 33 communicates with the high-pressure fuel inlet 39 through the second fluid passage 43. In this case, both the pressure control chamber 31 and the nozzle pressure chamber 33 are in a high-pressure state. A downward force difference acting on the needle valve element 29 is generated due to the fact that the diameter of the portion 29a of the needle valve element 29 defining the pressure control chamber 31 is larger than the diameter of the portion 29b of the needle valve element 29 located in the nozzle pressure chamber 33. As a result of this force difference together with the spring 37, the needle valve element 29 is urged toward the nozzle hole 35 so as to move longitudinally downward, and the conical tip 29c of the needle valve member 29 abuts against the nozzle hole 35, such that the nozzle hole 35 is occluded. Thus, the high-pressure fuel can't be injected out of the nozzle hole 35.
[0019] Next, the electromagnetic force generated by the electromagnetic coil 51 attracts the driving rod 47 to move upward away from the valve seat 45 against the urging force of the spring 59 when a current is supplied to the electromagnetic coil 51, such that the sealing head 49b of the sealing cone 49 is moved with the driving rod 47 away from the valve seat 45 and the pressure control chamber 31 in the high-pressure state communicates with the concave 53 defined by the valve seat 45 through the throttling passage 55. Since the concave 53 communicates with the external low-pressure circuit through the return passage 61, the pressure within the pressure control chamber 31 decreases rapidly. At this time, however, the nozzle pressure chamber 33 is still at a high pressure. The needle valve element 29 is moved axially upward against the urging force of the spring 37 and the hydraulic force caused by the pressure within the pressure control chamber 31 under the action of the high pressure within the nozzle pressure chamber 33, such that the conical tip 29c of the needle valve element 29 is moved away from the nozzle hole 35. Thus, high-pressure fuel from a fuel supply line (not shown) is injected into the combustion chamber of the engine via the high-pressure fuel inlet 39, the second fluid passage 43, the nozzle pressure chamber 33 and the nozzle hole 35.
[0020] The electromagnetic force disappears when the current supplied to the electromagnetic coil 51 is cut off, and the fuel injection device 1 returns to a closed state under the action of the urging force exerted by the spring 59 at the upper end of the driving rod 47, such that fuel injection is stopped. The process described above is performed repeatedly, thereby injecting the fuel continuously into the combustion chamber of the engine.
[0021] In an conventional fuel injection device where the sealing ball is employed to occlude the throttling passage, the shape of the sealing ball is fixed after the diameter of the sealing ball is determined, and the space gap defined by the valve seat and the sealing ball to allow high-pressure fuel to pass through when the throttling passage is opened is also determined, therefore the flow state and flow direction of the high-pressure fuel are also determined. Unlike the prior art, the fuel injection device according to the present utility model replaces the sealing ball with the sealing cone, and the sealing cone has the sealing head including the first truncated part and the second truncated or conical part connecting with the first truncated part. In this case, even in the instance that the diameter of the annular line (circle) between the first truncated part and the second truncated or conical part is already determined, the space gap defined by the valve seat and the sealing head of the sealing cone to allow the high-pressure fuel to pass through may still be changed by changing the angle formed by a generatrix of the first truncated part and/or a generatrix of the second truncated or conical part with respect to the surface of the conical concave so as to change the flow state and flow direction of the high-pressure fuel, thereby ultimately reducing or eliminating cavitation erosion and particle wear caused by the impact force produced as bubbles formed by the high-pressure fuel burst to the valve seat area around the throttling passage, and ensuring normal operation of the fuel injection device.
[0022] The present utility model has been described in detail above in conjunction with particular embodiments. Obviously, both the above descriptions and the embodiments shown in the drawings are to be construed as illustrative and not restrictive to the present utility model. For example, in a preferred embodiment, the pressure control valve assembly of the present utility model is described in conjunction with a fuel injection device, but it is to be understood that the pressure control valve assembly of the present utility model is applicable to any device in which high-pressure fluid is intermittently discharged and potential cavitation erosion and particle wear may be generated. It will be apparent to those skilled in the art that various alterations and modifications may be made without departing from the spirit of the present utility model, and that such alterations and modifications do not depart from the scope of the present utility model.
a housing (23);
a valve seat (45) formed by a part of the housing (23) and defining a conical concave (53);
a throttling passage (55) formed in the housing (23) and communicating a pressure control chamber (31) with the concave (53);
a return passage (61) formed in the housing (23) and communicating with the concave (53);
a driving rod (47) movable longitudinally in the housing (23);
a sealing cone (49) attached to the driving rod (47) so as to move with the driving rod (47), the sealing cone (49) being capable of abutting against a surface of the concave (53) to occlude the throttling passage (55) or moving away from the surface of the concave (53) to open the throttling passage (55);
an actuating means (51) for actuating the driving rod (47) so as to move the sealing cone (49) away from the surface of the concave (53); and
a spring (59) acting on the driving rod (47) so as to render the sealing cone (49) to abut against the surface of the concave (53);
characterized in that, the sealing cone (49) comprises a sealing head (49b) including a first truncated part (49c) adjacent to the driving rod (47) and a second truncated or conical part (49d) connecting with the first truncated part (49c), an annular line is formed between the first truncated part (49c) and the second truncated or conical part (49d), and the sealing cone (49) forms a sealing contact with the surface of the concave (53) at the annular line.
a pressure control valve assembly (27) according to any one of claims 1-5; and
a needle valve assembly (25);
wherein the needle valve assembly (25) opens to inject the fuel or closes to stop injecting the fuel according to changes in pressure within the pressure control chamber (31).
a needle valve element (29) disposed in the housing (23) and movable in a longitudinal direction, wherein the needle valve element (29) includes a part (29a) of a larger diameter, an other part (29b) of a smaller diameter and a conical tip (29c) formed at an end of the other part (29b) of the smaller diameter, the pressure control chamber (31) is defined by an end of the part (29a) of the larger diameter together with the housing (23);
a nozzle pressure chamber (33) defined by the housing (23) surrounding the other part (29b) of the smaller diameter;
a nozzle hole (35) formed in an end of the nozzle pressure chamber (33) and capable of being occluded or opened by the conical tip (29c);
a first fluid passage (41) formed in the housing (23) for communicating the pressure control chamber (31) with a high-pressure fuel inlet (39):and
a second fluid passage (43) formed in the housing (23) for communicating the nozzle pressure chamber (33) with the high-pressure fuel inlet (39).