JPH0874705A - Pressure valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid breakage of a return-flow valve spring by using a valve body of a delivery-valve closure member which opens in the direction of an injection point as a valve member of a return flow valve which opens in the opposite direction. SOLUTION: During the operation of a fuel injection pump, fuel highly pressurized in a pump working chamber 5 is pressure-fed in the direction of an injection point 7. In this case, a sleeve 13 operating as a valve body of a delivery-valve closure member 19 which opens toward the injection point 7 is allowed to remain pressed against a valve seat ring 47 with the aid of force of a belleville spring 49 and fuel passing through there. When fuel feed pressure of the pump working chamber 5 is reduced when the fuel force feed is completed, the delivery-valve closure member 19 is returned to a valve seat 17 by a compression spring 25. The pressure of fuel flowing toward the end face facing the injection point 7 of the delivery-valve closure member 19, and the end face of the sleeve 13, lifts up the sleeve 13 from a valve seat 45 of a return-flow valve 39 against the force of the belleville spring part. Thus, a part of fuel passes through an opened cross-section of the valve seat 45 of the return-flow valve 39 from the force feeding pipeline 3 to flow out into the pump working chamber 5 through the belliville spring 49.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pumping chamber of a fuel injection pump and a pumping conduit between a pump working chamber and an injection point provided in an internal combustion engine which is to be supplied with fuel by the fuel injection pump. A valve body having a valve seat, the valve body having a through passage, and further opening toward the injection point against the spring force. Is provided, the pressure valve closing member having a valve sealing surface, at which the pressure valve closing member cooperates with the valve seat of the valve body and further opens towards the pump working chamber. A return flow valve is provided, and the valve member of the return flow valve is held in a state of being pressed against a valve seat by a spring.

[0002]

2. Description of the Prior Art According to DE-A 420 2853, which is inserted in a pumping conduit between a pump working chamber of a fuel injection pump and an injection point provided in an internal combustion engine to which fuel is to be supplied. In the case of the known pressure valves, the high-pressure medium supplied to the pressure valve from the pump working chamber via a part of the pumping conduit causes the pressure valve closing member to oppose the force of the return spring from the valve seat to the injection point. Can be lifted in the direction of. This opens the pressure valve. At the end of the high pressure feed, the pressure valve closure member returns to the valve seat as the supply pressure in the pumping conduit decreases. At the same time, the injection valve closes at the injection point. This causes the pressure wave to reciprocate within the closed volume between the pressure valve and the injection valve. These pressure waves can re-open the injection valve and thus lead to an undesired after-injection at the injection point. In order to avoid this, a return flow valve is incorporated in this pressure valve closing member. Through this return flow valve, the pressure level in the pumping conduit is adjusted to the desired residual static pressure (Standdruc) even after the closing of the pressure valve closing member.
It can be reduced to k). This residual static pressure can be adjusted by the preload force of the return valve spring.

In the case of this known pressure valve, such a return valve is formed as a check valve in a known pressure valve which is constructed as an equal pressure valve. The check valve is inserted in the body of the pressure valve closing member. In this case, the ball acts as a check valve member. The ball is held against the conical valve seat by a return valve spring. In order to control the opening of a sufficiently large open cross section as quickly as possible, this check valve member carries out a relatively large stroke movement during the opening stroke movement in the direction of the pump working chamber. However, such a large opening travel distance also results in a large spring travel of the check valve spring, so that such a spring in this known pressure valve is particularly advantageous when the injection pressure is high.
Exposed to extremely large mechanical loads. Such a load may amplify and cause spring breakage, which in turn may lead to failure of the entire injection system.

[0004]

SUMMARY OF THE INVENTION The object of the invention is to improve a pressure valve of the type mentioned at the outset to provide a pressure valve in which breakage of the return flow valve spring is avoided.

[0005]

In order to solve this problem, in the structure of the present invention, the valve body of the pressure valve closing member that opens toward the injection point simultaneously has the valve member of the return flow valve that opens in the opposite direction. It was formed.

[0006]

The advantage of the pressure valve according to the invention is that by using the valve body of the pressure valve closing member which opens in the direction of the injection point as the valve member of the return flow valve, a large opening cross section is provided for this return valve. Since it is formed on the end face, the stroke of the valve member of the return flow valve can be small enough to sufficiently control the opening of the open cross section. Since such a small stroke requires only a small spring stroke of the return flow valve spring, the risk of spring breakage of the return flow valve spring is considerably reduced compared to known pressure valves.

Furthermore, the advantage of using the valve body of the pressure valve closing member at the same time as the valve member of the return flow valve is that the assembly of the entire pressure valve formed as a pressure equalizing valve is structurally simple. . This can reduce the manufacturing cost.

The valve body of the pressure valve closing member is formed as a sleeve, which is inserted into the guide hole of the pressure valve inside the pumping conduit and at the end face of the sleeve facing the injection point of the pressure valve closing member. It is advantageous if the valve seat and the valve sealing surface of the return valve member are also arranged. The valve sealing surface of the return valve member cooperates with a conical valve seat fixed to the casing. The valve seat may be arranged on a valve seat ring or a guide sleeve press-fitted in the guide hole. A return flow valve spring is attached to the end surface of the sleeve on the pump work chamber side. The return valve spring is preferably designed as a disc spring. This allows an extremely high injection pressure and a corresponding return force. The preload of the Belleville spring, which is adjustable in the pumping conduit for adjusting the residual static pressure, can be formed via an adjusting screw threaded into the guide hole, which axially limits the Belleville spring on the other side. it can.

The throttle downstream of the return valve in the direction of the pump working chamber is preferably formed with a throughflow cross section which is left between the outer peripheral surface of the sleeve and the inner wall of the guide hole. Alternatively, in the case of a sealing disc spring, this diaphragm can also be formed by a slit provided on the underside of the sleeve.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will now be described with reference to the embodiments shown in the drawings.

FIG. 1 shows a pressure valve 1 formed as an equal pressure valve.
FIG. This pressure valve is inserted in a casing (not shown) of the fuel injection pump, and in this casing, the injection chamber provided in the pump working chamber 5 of the fuel injection pump and the internal combustion engine to which the fuel is to be supplied is provided. It is inserted in a pumping conduit 3 which extends between the injection point 7 in the form of a valve.
The pressure valve 1 is arranged on a pipe piece 9 which can be screwed into the pump casing. The inside of this tube piece has a guide hole 11 formed as a stepped hole in the axial direction. In this guide hole, the individual components of the pressure valve 1 are guided in the axial direction. In the guide hole 11, the sleeve 13
A valve body of the form is arranged. The inside of this sleeve forms an axial passage 15, and a conical valve seat 17 is formed at the transition to the passage 15 on the annular end face of this sleeve facing the injection point 7. . This valve seat 17
Together with the cylindrical pressure valve closing member 19 which projects into the through passage 15 and opens in the direction of the injection point 7. A collar 21 provided on this pressure valve closing member has a conical valve sealing surface 23. With this valve sealing surface, the pressure valve closing member 19 is held in a state of being pressed against the valve seat 17 by the compression spring 25. Furthermore, the pressure valve closing member 19 has, in a known manner, a vane-shaped guide surface below the valve sealing surface 23. These guide surfaces are guided in the through passage 15 of the sleeve 13, and fuel can flow from the pump working chamber 5 toward the valve seat 17 between the guide surfaces. In the case of the first embodiment shown in FIG.
The compression spring 25 is clamped between an annular step portion 27 provided on the collar 21 of the pressure valve closing member 19 and a collar 29 of the filler 31 inserted into the guide hole 11. The filling material is held on the step portion of the guide hole 11 by the compression spring 25. The end face of the cylindrical shank 33 of the filling material 31 which projects in the direction of the pressure valve closing member 19 limits the opening stroke movement of the pressure valve closing member 19 in the direction of the injection point 7. A through hole 35 is provided in the filler 31 in the axial direction so that the fuel flow is not obstructed. This through hole 35 is connected to the pressure-feeding conduit 3 leading to the injection point 7 and is crossed by a lateral hole 37. This lateral hole is opened in the enlarged diameter portion of the guide hole 11 that is provided following the valve seat 17.

A return flow valve 39, which opens towards the pump working chamber 5, is incorporated in the pressure valve 1 in order to be able to reduce the pressure in the pumping conduit 3 to a defined value after the end of the injection operation. According to the invention, the sleeve 13 is used not only as the valve body of the pressure valve closing member 19 but also as the return flow valve member 41. For this purpose, the guide hole 11
The annular end surface of the sleeve 13 which is axially displaceable therein in the direction of the injection point 7 is located radially outwardly at the transition to the cylindrical outer peripheral surface, the valve sealing surface 43 of the conical return valve. have. This valve sealing surface 43 cooperates with the valve seat of the return valve 39 fixed to the casing. Such a valve seat 45 is arranged on the lower end surface of the valve seat ring 47 press-fitted in the guide hole 11 facing the pump working chamber 5. A cross-flow cross section is left between the inner wall surface of the valve seat ring 47 and the cylindrical outer peripheral surface of the collar 21 provided on the pressure valve closing member 19. The lower end of the sleeve 13 facing the pump working chamber 5 is loaded by a disc spring 49. This disc spring holds the valve sealing surface 43 of the sleeve 13 in a state of abutting against the valve seat 45. The other side of the disc spring 49 is supported by the end face of an adjusting screw 51 screwed into the guide hole 11 on the pump working chamber side. The spring preload (spring preload) can be adjusted via the screwing depth of the adjusting screw. Pressure valve closing member 19
Projects into the area of the adjusting screw 51 through an axial through opening in the disc spring 49.

A cross-flow cross section is provided between the outer peripheral surface of the sleeve 13 and the inner wall of the guide hole 11 so that the return flow of the fuel is not obstructed when the return flow valve 39 is opened. This flow-through cross section can be formed as a throttle section which is placed after the valve seat 45 of the return valve. In the case of the seal disc spring 49, such a throttle section can be formed by the slit 53 provided on the lower surface of the sleeve 13. The first embodiment of the pressure valve according to the invention, shown in FIG. 1, works as follows.

During operation of the fuel injection pump, the high-pressure fuel in the pump working chamber 5 of the fuel injection pump is pumped toward the injection point 7. This fuel flows along the guide surfaces of the pressure valve closing member 19 toward the valve surfaces of these guide surfaces, and when the predetermined feed pressure is exceeded, the pressure valve closing member 19 resists the return force of the compression spring 25. Then valve seat 1
Since it is lifted from 7, fuel can flow into the pumping conduit 3 leading to the injection point 7 by scraping the valve seat 17 of the pressure valve closing member 19. Then, at this location, the fuel is injected into the combustion chamber of the internal combustion engine that is to be refueled. In such a flow direction, the sleeve 13, which acts as the valve body of the pressure valve closing member 19 which opens in the direction of the injection point 7, is assisted by the force of the disc spring 49 and possibly the fuel flowing therethrough, so that the valve seat ring. It is located as it is applied to 47.

When the feed pressure of the fuel in the pump working chamber 5 decreases at the end of the fuel pressure feeding, the force of the fuel flowing toward the pressure valve closing member 19 opens the pressure valve closing member against the force of the compression spring 25. It is no longer sufficient to keep the pressure valve closed and returns to the valve seat 17.
At the same time, the injection valve closes at the injection point 7. The pressure level of the pressure wave peak pressure is reduced via the return valve 39 to a predetermined amount in order to avoid a post-injection at the injection point 7 by a reciprocating pressure wave in the closed volume. The fuel pressure flowing toward the end face of the pressure closing member 19 facing the injection point 7 and the end face of the sleeve 13 lifts the sleeve 13 from the valve seat 45 of the return flow valve against the force of the disc spring 49. , A part of the fuel flows from the pressure-feeding conduit 3 through the cross section between the collar 21 and the valve seat ring 47, and the valve seat 4 of the return valve.
5 through the open cross section and the throttled section between the sleeve 13 and the guide hole 11 and into the pump working chamber 5 via the disc spring 49.

The difference between the second embodiment shown in FIG. 2 and the first embodiment shown in FIG. 1 lies in the structure of the pressure valve closing member and the filling material, and the pressure valve closing member and the filling material. In the configuration of the compression spring clamped between and. Therefore,
The second embodiment will be described by limiting to these components.

In the second embodiment, the pressure valve closing member 219 is formed in a pot shape. The closed end surface projects in the direction of the pump working chamber 5. At the transition of this closed end surface of the compression valve closing member 219 to the cylindrical outer peripheral surface, a conical valve sealing surface 223 is formed by oblique chamfering. This valve sealing surface has a conical valve seat 1 provided on the sleeve 13 as in the first embodiment.
Work with 7. A compression spring 225, which holds the pressure valve closing member 219 in a state of being pressed against the valve seat 17, is guided in an inner hole 61 of the pressure valve closing member 219, and one end of the compression spring has an inner hole. It is supported by the annular stepped portion 227 of 61, and the other end thereof is supported by a support ring 63 inserted into the guide hole 11 and fixed to the casing.
To allow fuel flow through the pressure valve closure member 219, the pressure valve closure member has a beveled hole 65 extending radially outward from the inner bore 61. This oblique hole is inclined toward the pump working chamber 5 and opens into the annular chamber 67 formed by the step portion of the cylindrical outer peripheral surface of the pressure valve closing member 219. This annular chamber reaches the valve seat 17 of the sleeve 13 and the sealing surface 43.
The annular chamber 67 is bounded radially outward by a guide sleeve 69 which is fixedly inserted in the guide hole. Like the valve seat ring 47 of the first embodiment, this guide sleeve has a valve seat 245 of the return flow valve 239 on the end surface facing the pump working chamber 5. The valve sealing surface 43 of the sleeve 13 is applied to this valve seat in a known manner by means of a disc spring 49. The end of the guide sleeve 69, which is remote from the pump working chamber 5, is guided by the annular step of the support ring 63, which guide sleeve closes the inner wall of the guide sleeve and the pressure valve closure guided in this guide sleeve. A throughflow cross section is formed between the member 219 and the member 219. This flow-through cross section can be formed in a known manner by the gap between the guide surfaces of the pressure valve closing member 219.

Furthermore, the second embodiment shows another possibility of fuel flow through the sleeve 13. In this sleeve, a throttle hole 71 leading to the through passage 15 from the cross-flow cross section between the outer wall surface of the sleeve 13 and the wall of the guide hole 11.
Is provided. Through this throttle hole 71, the returning fuel is throttled after passing through the return flow valve 239 and flows out into the pump working chamber 5. The pressure valve of the second embodiment shown in FIG.
Works as in the example. However, in the case of this second embodiment, the pressure valve closing member 219 is guided axially in the guide sleeve 69, not in the sleeve 13, so that the opening stroke movement of the pressure valve closing member 219 is Limited by being applied to the support ring 63. In the case of the second embodiment, the fuel flows into the annular chamber 67 along the valve seat 17 in the direction of the injection point 7 and then from this location along the outer peripheral surface of the pressure valve closing member 219 in the pumping conduit 3. Flow into. By applying the pressure valve closing member 219 to the support ring 63, the fuel flows through the oblique hole 6
5 through the pressure valve closing member 219.

When the pressure is reduced after the high-pressure feed has ended, the fuel likewise flows from the pressure-feeding conduit 3 into the annular chamber 67, and from this point along the throttle section 71 via the valve seat 245 controlled to open. Return to the pump work room 5.

Therefore, with the pressure valve according to the invention,
The return flow valve is provided with the largest possible cross-flow cross-section to allow a small opening stroke controllable by a sturdy disc spring to ensure spring break of the return flow valve opening towards the pump working chamber. To be avoided. In this case, it is particularly advantageous if the valve body of the pressure valve opening in the direction of the injection point and the valve element of the return valve are designed as a common component in the form of a sleeve.

[Brief description of drawings]

1 shows a first pressure valve formed as an isostatic valve, in which the pressure valve closing member projects axially into a sleeve forming the valve body of the pressure valve closing member and the return flow valve member, FIG. It is a longitudinal section showing an example.

2 shows a second pressure valve formed as an isostatic valve, in which the pressure valve closing member is axially connected to the sleeve, which pressure valve closing member is guided in an additional guide sleeve. It is a longitudinal section showing an example.

[Explanation of symbols]

1 pressure valve, 3 pumping conduit, 5 pump working room,
7 injection points, 9 tube pieces, 11 guide holes, 13
Sleeve, 15 through passage, 17 valve seat, 19 pressure valve closing member, 21 collar, 22 valve sealing surface, 25
Compression spring, 27 annular step, 29 collar, 31
Filler, 33 Shaft, 35 Through Hole, 37 Transverse Hole, 39 Return Flow Valve, 41 Return Flow Valve Member, 4
3 valve sealing surface, 45 valve seat, 47 valve seat ring,
49 disc spring, 51 adjusting screw, 61 inner hole, 6
3 support ring, 65 oblique hole, 67 annular chamber, 69
Guide sleeve, 71 throttle hole, 219 pressure valve closing member, 223 valve sealing surface, 225 compression spring, 227 annular step portion, 239 return flow valve

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Herbert Schumacher, Federal Republic of Germany Gerlingen Mühlstraße 36

Claims (14)

[Claims] 1. A pump working chamber (5) of a fuel injection pump.
A valve seat (1) which is to be installed in a pressure-feeding conduit (3) between a fuel injection pump and an injection point (7) provided in an internal combustion engine.
7) is provided, which valve body has a through passage (15) and which further opens against the spring force towards the injection point (7). 19, 21
9) is provided, the pressure valve closing member having a valve sealing surface (23, 223) at which the pressure valve closing member cooperates with the valve seat (17) of the valve body. , And a return flow valve (39, 23) that opens toward the pump working chamber (5).
9) is provided, and the valve member of the return flow valve is a spring (4
9) in the form of being held against the valve seat (45, 245) by a pressure valve closing member (19, 19) which opens towards the injection point (7).
219) has a valve body with a return flow valve (39,
239) is also formed as a valve member,
Pressure valve. 2. The valve body is embodied as a sleeve (13), the sleeve having on its upper end face facing the injection point (7) a valve seat (17) for a pressure valve closing member (19, 219). ) And a return valve seat (4
5,245) and a valve sealing surface (43) cooperating with the sleeve such that the valve seat (17) is located radially inward and the valve sealing surface (43) is located radially outward. The pressure valve according to claim 1, which is formed in (13). 3. The end surface of the sleeve (13) facing the pump working chamber (5) is loaded by a compression spring, which compression spring is provided on the valve sealing surface (4) of the sleeve (13).
The pressure valve according to claim 2, wherein 3) is held in a state of being crimped to the valve seat (45, 245). 4. A flow-through cross section at least partially between the cylindrical outer peripheral surface of the sleeve (13) and the inner wall of a guide hole (11) formed as a stepped hole, which accommodates the entire pressure valve device. The pressure valve according to claim 3, wherein the pressure valve is provided. 5. The pressure valve as claimed in claim 4, wherein the compression spring which loads the sleeve (13) is embodied as a disc spring (49). 6. An adjusting screw (5) in which an end face of the disc spring (49) separated from the sleeve (13) is screwed into a guide hole.
6. The pressure valve according to claim 5, which is axially applied to 1). 7. A pressure valve closing member (19) is axially guided in the through passage (15) of the sleeve (13) and a valve seat (45) of the return valve (39) is provided with a guide hole. (1
The valve seat ring (47) fixedly inserted in 1) is arranged on the lower end surface facing the pump working chamber (5), and the inner wall surface of the valve seat ring and the outer peripheral surface of the pressure valve closing member (19). (21) provided after the valve sealing surface (23) between
7. The pressure valve according to claim 6, wherein a throughflow cross section is provided at the height of. 8. A compression spring (2) for the pressure valve closing member (19).
5) is an annular step portion (27) formed on a side of the collar (21) of the pressure valve closing member (19) separated from the valve sealing surface (23), and an annular step portion fixed to the casing. The pressure valve of claim 7, wherein the pressure valve is clamped between the pressure valve and the pressure valve. 9. An annular step, which is fixed to the casing, is formed by a collar (29) provided on a cylindrical filler (31), and this filler is pumped to the injection point (7). Axial through-hole (3) connected to conduit (3)
9. The pressure valve according to claim 8, comprising 5), the through-hole being intersected by at least a transverse hole (37). 10. The valve seat (245) of the return flow valve (239).
Is arranged on the lower end face of the guide sleeve (69), which is firmly inserted into the guide hole (11), facing the pump working chamber (5), and inside this guide sleeve, the pressure valve closing member (219). ) Is slidably guided in the axial direction, and the pressure valve closing member (219) and the guide sleeve (6).
7. The pressure valve according to claim 6, wherein a cross-flow cross section remains between the pressure valve and the pressure valve. 11. A pressure valve closing member (219) is formed in the shape of a pot, and one end of a compression spring (225) projects into an opening facing the injection point (7). 11. The pressure valve according to claim 10, wherein is clamped between the annular step of the inner bore (61) of the pressure valve closing member (219) and the annular step fixed to the casing. 12. The inner hole (6) of the pressure valve closing member (219).
1), at least one bevel (65) is provided with a valve seat (1
12. The pressure valve according to claim 11, which is led to an annular chamber (67) adjacent to 7). 13. The return flow valve (39, 239) is provided downstream with a throttled portion, the throttled portion being formed between the sleeve (13) and the guide hole (11),
And / or the outer peripheral surface of the sleeve (13) and the through passage (1
The pressure valve according to claim 6, which is formed by a throttle hole (71) provided between the pressure valve and the pressure valve. 14. The valve sealing surface (23, 223) and valve seat (17) as well as the return flow valve seat (45, 245) and the valve sealing surface (43) provided on the sleeve (13) are conical. Pressure valve according to any one of claims 2 to 13, which is formed.