JPH0368233B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The invention relates to a reciprocating pump piston which delimits the pump casing and the pump working chamber, and which is mounted in the discharge conduit to the injection valve and connected via a connecting piece. A fuel injection pump for an internal combustion engine having an isobaric relief valve fixed to the pump casing, the pressure relief valve opening in the direction of fuel delivery against the force of the valve casing and the pressure valve spring. It consists of a valve body and a relief valve which opens opposite to the delivery direction and forms a component together with the pressure valve body, the valve spring of the relief valve being supported on the pressure valve body and the casing of the relief valve being It is formed as a pot-shaped filling member mainly arranged inside the pressure valve spring, and the filling member is attached to the cylindrical protrusion of the pressure valve body and has a relief valve. related to things.

PRIOR ART In the case of known fuel injection pumps of this type with isobaric relief valves, a filling member for receiving the relief valves has conventionally been necessary in order to reduce the dead volume, and the pressure valve springs have been is used in place of the filling member held inside the connecting piece by
In some cases, it also serves as a stroke limiter for the pressure valve body. In such configurations, the installation space is small and the pressure valve with or without a return suction flange can also be converted into an isobaric relief valve while maintaining the minimum number of components present. be done. This allows conventional fuel injection pumps to be easily modified or retrofitted. However, the use of such isobaric relief valves has heretofore had the disadvantage that the pressure valve spring of the relief valve can tear the entire component apart during assembly or disassembly of the valve or valve body. This can result in individual components being lost or falling unobserved into the pump working chamber, resulting in the destruction of the entire injection pump.

Problem to be Solved by the Invention The problem to be solved by the present invention is to solve the problem when removing the connecting pipe piece.
The object is to construct the isobaric relief valve of a fuel injection pump of the type described above in such a way that the component consisting of the pressure valve body and the filling member receiving the relief valve remains together.

Means for Solving the Problems The measures taken to solve the above-mentioned problems are that the isobaric relief valve is equipped with a conveyance safety device, the conveyance safety device has at least one safety ring, and the The safety ring prevents the connecting tube from being removed.
and when the pressure valve spring is removed, the component consisting of the pressure valve body and the filling member including the relief valve is kept together.

Effects of the Invention The conveyance safety device in the fuel injection pump according to the present invention allows the valve component group mainly consisting of the pressure valve body and the filling member to be easily removed when the connecting pipe piece is removed and when the pressure valve spring is removed. , can be kept together.

Further advantageous embodiments and improvements of the device according to the invention are possible by means of the measures specified in the subclaims. In short, claim 2
In the case of the conveyance safety device described in Claim 3, the valve component group consisting of the pressure valve body and the filling member is also combined when the pressure valve spring is removed, and furthermore, as described in Claim 3, With this construction, the snap-type coupling device according to the invention is realized in a simple manner.

Example The invention will be explained below with reference to the exemplary embodiments shown.

Bore 10 of the pump casing 11 of the first embodiment of the injection pump, only partially shown in FIG.
A pump cylinder 12 is fitted in the cylinder bore 13 of the pump cylinder.
Pump piston 15 with 4 slides. The known parts of the cam gear and the rotation device for changing the amount are not shown. The cylinder bore 13 has a pump working space 16 which is bounded on one side by the end face 17 of the pump piston 15 and on the other side by an isobaric relief valve 18 .

The isobaric relief valve 18 has a pressure valve body 22 in the valve housing 19 which is disengaged from the valve seat 21 against the force of a pressure valve spring 20 in the discharge direction of the fuel diameter during the opening stroke. A flange 23 located on the underside of the valve housing 19 is clamped against the cylinder bushing 12 by a connecting tube piece 25 screwed into the pump housing 11, and the cylinder bushing is inserted into the pump housing 11. is being held,
Further, the end surfaces where the valve casing 19 and the pump cylinder 12 come into contact are metallically sealed.

A relief valve 26 is attached to the pressure valve body 22, which relief valve 26 forms a unit with the pressure valve body 22. A valve seat 27, a movable valve element 28 formed by a ball, a socket-shaped filling element 31 with a valve spring and a spring collar 30 serve as a housing for the relief valve 26.

The sleeve-shaped section 31a of the filling member 31
It has a pressure valve spring 20 and projects into a chamber 32 surrounded by the pressure valve spring, which reduces the dead volume between the pressure valve 18 and the injection nozzle. Ru. Sleeve-shaped section 31
A flange 31b that expands toward the pressure valve body 22 is connected to a, and a cylindrical notch 31 that expands into a conical shape on the end face side is connected to the flange 31b.
c is integrally molded, and a cylindrical projection 22b of the same diameter projects from the stepped end surface 22a of the pressure valve body 22 into the notch. The filling element 31 thereby ensures that the pressure valve body 22, which would otherwise form a bearing for the pressure valve spring 20,
It is attached to the stepped end surface 22a,
Moreover, the pressure valve body 22 and the filling member 31 are brought together in the assembled state shown in the figure by a transportation safety device 45. The transport safety device 45 has a flaring ring serving as a safety ring 46, which engages a ring groove 48 in the pressure valve body 22 by means of a first edge 46a which is flanged at least section by section. The flange 31b of the filling member 31 is secured by the matching and annular second edge 46b.
surrounding. Said second edge 46b is fixedly clamped between the pressure valve spring 20 and a projection 33 formed at the transition between the flange 31b and the sleeve-like section 31a of the filling member 31 and 46b itself forms a bearing for the pressure valve spring 20.

In FIG. 1A, a modified embodiment of a safety ring 46 is shown in dashed lines, which also includes a second edge 46 which is flanged at least in sections.
c into a ring groove 47 formed integrally with the flange 31b of the filling member 31. First edge 46 in the previously described embodiment of safety ring 46
If a or the second edge 46c in the variant embodiments is also flanged or bent in only one place, the associated ring grooves 48, 47 do not have to be designed annularly and can receive said edges 46a or 46c. It is advantageous in terms of costs if the corresponding part of the outer periphery is formed by cutting.

The contact surface between the filling member 31 and the pressure valve body 22, e.g. , processed as a sealing surface. In this case, the required sealing force is the pressure valve spring 20
Therefore, in all operating conditions the safety ring 46 does not need to transmit or receive axial forces.

Valve seat 27 of relief valve 26 designed as a ball valve
is provided with a load relief hole 35, the pressure valve body 22
It is integrally molded on the inner bottom surface of the bottom 36 of the filling member 31 on the opposite side.

The pressure valve body 22 has a cylindrical protrusion 22b.
A concentric backflow hole 38 is provided in the range between the pressure valve body 22 and the seal conical portion 22c, and the backflow hole can pass through the pressure valve body in the longitudinal axis direction depending on the configuration of the pressure valve body 22 (the second (see figure), or opens into a horizontal hole 39 at the lower side of the sealing cone 22c that cooperates with the valve seat 21 as shown in FIG. Fuel returns to the pump work chamber 16 through the backflow hole 38 with an associated transverse hole 39, controlled by the relief valve 26, through the inside of the filling element 31, when the valve seat 21 is closed. bypass. The load relief hole 3 is flowed through during load relief in order to dampen the isobaric load relief and to reduce unrestrained vibrations of the relief valve 26.
5. At least one of the backflow hole 38 and the lateral hole 39, for example the load reduction hole 35, is formed as a throttle hole. The backflow hole 38 or the horizontal hole 3 that follows the load reduction hole 35 during equal pressure load reduction.
9 is also formed as a diaphragm hole. In this case, the two throttle holes are synchronized with each other in such a way that undesirable vibrations of the valve member 28 are eliminated and thereby an equal pressure relief, which is synchronized by the tensioning force of the valve spring 29, takes place. There must be. Due to the damped unloading of the fuel volume existing between the isobaric relief valve 18 and the injection nozzle, the pressure waves generated in the discharge conduit, designated 42, leading to the injection nozzle are also significantly reduced; A worrying after-injection at the injection nozzle therefore does not occur.

The isobaric relief valve 18' in the second embodiment shown in FIG. 2 is similar to the isobaric relief valve 18' shown in FIG.
Unlike the pressure valve body 22', the pressure valve body 22' is provided with a sealing conical portion 22c' located on the lower side, and a conveyance safety device 45' is provided in the range of the flange 31b' of the filling member 31'. The safety device
It is designed as a snap-type connection which allows a slight axial movement of the filling member 31' relative to the pressure valve body 22'. Such transportation safety device 4
5' prevents the following when removing the equal pressure relief valve 18'. That is, when the pressure valve spring 20 is removed, the valve spring 29 of the relief valve 26 presses the component group consisting of the filling element 31' and the pressure valve body 22' against each other and the relatively small part of the relief valve 26, i.e. the valve element. 28, valve spring 29, and spring collar 30 are prevented from being lost and possibly falling into the pump working chamber 16.

The transport safety device 45' is formed by a retaining ring, which is clearly shown in FIG. 2A, which shows section A' in FIG. The wire cross section of approximately half of each of the filling members 31'
and one annular groove 47' and 4 integrally formed in the mutually facing walls of the valve body 22'.
8'. One ring groove 47' is formed integrally with the cylindrical cutout 31c' of the filling member 31', and the other ring groove 48' is integrally formed with the cylindrical projection 22b' of the pressure valve 22'. The ring groove 48' in the cylindrical projection 22b' has the same width as the wire diameter of the safety ring 51 and essentially guides the safety ring in the axial direction; It is integrally molded into the protrusion 22b' with a depth sufficient to completely accommodate the safety ring 51 to be pressed.
According to the present invention, the ring groove 47' is provided with a safety ring 51.
and has a play a relative to the ring groove 47', for example in the delivery direction, so that during normal operation of the valve, almost no axial load is applied to the safety ring 51. Not communicated. The stepped end face 22a' is sloped at a gentle angle and the conical side wall (not shown) of the ring groove 47' may in some cases close to the relief valve 2.
It is possible to withdraw the filling member 31' so that the components 6 can be replaced or re-adjusted.

Pressure valve bodies 22, 22' of all embodiments shown without return suction flange, which serves to reduce the isobaric load.
differs from ordinary check valves in that it has one cylindrical recess 37 in addition to the above-mentioned backflow hole 38 (see Figures 1 and 2) and side hole 39;
The recess forms a bearing for the valve spring 29.
If the isobaric relief valves 18, 18', in addition to the required isobaric offloading, also control one isoventricular offloading, the pressure valve bodies 22, 22' can, of course, be replaced, for example, by the sealing cone of FIG. The underside of 22c can also be provided with a known return suction flange. Another example of such use is for example Swiss Federal Patent No.
394710. Embodiments without a return suction flange are of course limited by this, due to the small valve stroke.
This has the advantage that the mass of the relief valve 26 added to the mass of the pressure valve body 22, 22' does not have any adverse effects.

When additionally equipping an existing fuel injection pump with the equal pressure relief valve according to the present invention, FIGS.
In the case of a configuration corresponding to the diagram, the pressure valve body 2 is also
2, 22' are reworked, and the valve housing 19, the pressure valve spring 20 and the connecting piece 25 are used unchanged.

Since the mode of operation of the above-mentioned equal pressure relief valves 18, 18' is almost the same as that of known equal pressure relief valves,
A brief explanation will be given below based on the embodiment shown in FIG.

During the delivery stroke of the injection pump shown in FIG. 42 to the injection nozzle. At the end of injection, the inclined control edge 14 on the pump piston 15
controls the opening of the control hole 43 in the wall of the pump cylinder 12, causing a sudden drop in the pressure in the pump working chamber 16, causing the pressure valve body 22 of the equal pressure relief valve 18 to close to the valve seat 21.
, and the residual pressure present in the discharge conduit 42 and also in the chamber 32 causes the chamber 32 to close the pump working chamber 1.
The relief valve 2 is connected to the relief valve 2 through the load reduction hole 35 connected to the
6 valve member 28. Such a relief valve 2
6 is pushed open to connect the chamber 32 with the depressurized pump working chamber 16 via the backflow hole 38 and the transverse hole 39. The spring tension of the valve spring 29 of the relief valve 26 and the relieving hole 35 and/or the transverse hole 39, which may be configured as a throttle hole, also define the pressure height and the speed, which pressure height The load reduction is performed at or at that speed. The transport safety device 45 does not affect or impair the functionality of the isobaric relief valve 18. The transport safety device 45 operates only when the equal pressure relief valve 18 is removed, and the pressure valve body 22
and prevents the filling member 31 from falling apart and thereby preventing the filling member 31 from falling apart.
This prevents the internal components of the relief valve 26 from falling out.

The mode of operation of the isobaric relief valve 18' shown in FIG. 2 is the same as in the first embodiment according to FIG. 1, apart from the difference in the construction of the transport safety device 45'.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view showing a first embodiment of the device according to the present invention, FIG. 1A is an enlarged view of part A in FIG. 1,
FIG. 2 is a longitudinal sectional view showing the second embodiment, and FIG. 2A is an enlarged view of portion A' in FIG. 10... Hole, 11... Pump casing, 12... Pump cylinder, 13... Cylinder hole, 14... Slope control edge, 15... Pump piston, 16... Pump working chamber, 17... End face, 18, 18'... Equal pressure relief valve, 1
9... Valve casing, 20... Pressure valve spring, 21... Valve seat, 22, 22'... Pressure valve body, 22a, 22a'...
End face, 22b, 22b'...Protrusion, 22c, 22
c'... Seal cone, 23... Flange, 25... Connection pipe piece, 26... Relief valve, 27... Valve seat, 28... Valve member, 29... Valve spring, 30... Spring groove, 31,3
1′...Filling member, 31a...Division, 31b, 31
b'...flange, 31c, 31c'...notch, 32
...Chamber, 33...Protrusion, 35...Load reduction hole, 36...
Bottom, 37... recess, 38... backflow hole, 39... horizontal hole, 4
2...Discharge conduit, 43...Control hole, 45, 45'...Transfer safety device, 46...Safety ring, 46a, 46
b, 46c...rim, 47, 47', 48, 48'...ring groove, 51...safety ring.

Claims (1)

[Claims] 1. Pump casing 11 and pump working chamber 16
Fuel for an internal combustion engine with a reciprocating pump piston 15 limiting the movement of the pump and an isobaric relief valve 18 mounted in the discharge conduit 42 to the injection valve and fixed to the pump casing 11 via a connecting conduit 25 In the injection pump, the equal pressure relief valve 18 is connected to a valve casing 19, a pressure valve body 22 which opens in the direction of fuel delivery against the force of a pressure valve spring 20, and a pressure valve body 22 which opens in the opposite direction to the delivery direction and releases pressure. It consists of a relief valve 26 which together with the valve body 22 forms a component, the valve spring 29 of which is supported on the pressure valve body 22 and the casing of the relief valve 26 is supported by the pressure valve spring 20.
A pot-shaped filling member 3 mainly arranged inside the
1, in which the filling member 31 is attached to the cylindrical protrusion 22b of the pressure valve body 22 and has a relief valve 26, the equal pressure relief valves 18, 18 ' is equipped with a conveyor safety device 45, 45', which conveyor safety device has at least one safety ring 46, 51, which protects the connecting tube 25 and the pressure valve. A device for an internal combustion engine, characterized in that, when the spring 20 is removed, the constituent unit consisting of the pressure valve bodies 22, 22', the filling member including the relief valve 26, and 31, 31' is kept together. fuel injection pump. 2. Fuel injection pump according to claim 1, wherein the conveying safety device 45' is designed as a snap-type connection allowing a slight axial movement of the filling member 31' relative to the pressure valve body 22'. 3. The filling element 31 consists of a sleeve-shaped section with a relatively small diameter that projects into the pressure valve spring 20 and an enlarged flange, the end side of the filling element 31' in the area of the flange 31b' being is provided with a cylindrical recess 31c', which recess has a diameter larger than the inner diameter of the sleeve-shaped section 31a and in which a cylindrical projection of the pressure valve body 22' is disposed. 22b' protrudes, and furthermore, both the cylindrical notch 31c' of the filling member 31' and the cylindrical projection 22b' of the pressure valve body 22' each have a single integrally formed part in the walls facing each other. It has ring grooves 47', 48', and a retaining ring which engages in both ring grooves 47', 48' and serves as a safety ring 51 together with the ring grooves forms a transport safety device 45'. A fuel injection pump according to claim 2.