JPS6356428B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel injection valve holder, and more particularly to a two-stage opening pressure type fuel injection valve holder that can provide a throttle period to a Hall type fuel injection valve used in a direct injection diesel engine. This device facilitates adjustment of the valve opening pressure and adjustment of the needle valve lift amount during the throttle period.

Due to its characteristics, diesel engines
Since CO and HC emissions are low in the exhaust gas, it is only necessary to reduce nitrogen oxides in order to comply with exhaust gas regulations. To achieve this, the injection start time is delayed,
It is necessary to reduce the maximum combustion temperature. However, if the injection start time is delayed with a conventional fuel injection valve, the end of injection will be too late, and the CO, HC, smoke, etc. in the exhaust gas will be seriously deteriorated.
It was unusable. Therefore, the fuel injection rate,
In other words, while increasing the injection amount per unit rotation angle and delaying the injection start time, the end of injection can be controlled by CO, HC,
A method has been adopted in which the process is advanced within a range that does not cause deterioration such as smoke. However, an increase in the injection rate necessarily accompanies a shortening of the relative injection time, which poses the problem of short-term combustion that causes combustion noise.

This problem can be solved by providing a throttle period at the beginning of injection, reducing the injection rate at the beginning of injection, and preventing sudden and explosive combustion. Such fuel injection valves that can obtain a throttle period are already known as pin-type nozzles used in pre-combustion type or swirl chamber type engines, and hall-type nozzles used in direct injection type engines. It was not possible to obtain such a throttle period with a nozzle.

In order to solve this problem, a first nozzle spring and a second nozzle spring are provided, and only the first nozzle spring acts at the initial stage of injection to lower the valve opening pressure and limit the needle valve lift to a small value at the initial stage. Two-stage valve opening pressure type fuel injection that creates an injection stroke (throttle period), and in the subsequent main injection, the first and second nozzle springs act simultaneously to increase the valve opening pressure and create a main injection stroke that achieves maximum lift. A valve is already known as Japanese Patent No. 145495, Japanese Patent Publication No. 47-46807 and Japanese Utility Model Publication No. 53-52987. However, with these fuel injection valves, it is difficult to individually adjust the initial injection lift amount, adjust the set load of the second nozzle spring that acts from the beginning of injection, and adjust the set load of the first nozzle spring that acts on the main injection. However, it was often said that it was almost impossible to ensure overall adjustment.

In order to solve this problem, the present applicant proposed a fuel injection valve (Utility Model Application No. 56-129568), for example, as shown in FIG. is held by the holder main body 3, and at the time of initial injection, the first movable spring seat 4 is displaced by the lift of the nozzle needle valve 1, compressing the first nozzle spring 5 to perform the initial injection lift Δl, and then at the time of main injection. The first movable spring seat 4 pushes up the second movable spring seat 6 and the second nozzle spring 7
At the same time, the main injection lift l is performed. That is, the first movable spring seat 4 and the second movable spring seat 6 are provided separately, and the first nozzle spring 5 and the second nozzle spring 7 are respectively pressed, and the initial injection valve opening pressure and the main injection opening pressure are The valve pressure can be set independently. The initial injection valve opening pressure can be set by selecting the thickness of the first nozzle spring adjusting shim 8 interposed between the first nozzle spring 5 and its spring seat. Adjust the load so that it matches the initial injection valve opening pressure. The main injection valve opening pressure is set by rotating and lowering the male screw member 9 that hooks the second movable spring seat 6, and connecting the upper end of the first movable spring seat 4 with the push rod 6a of the second movable spring seat 6. Adjust the second nozzle spring 7 in the male threaded member 9 by rotating the second nozzle spring adjustment screw 10 while the lower ends of the first nozzle spring 5 and the second nozzle spring This is done so that the sum of the set loads becomes a predetermined main injection valve opening pressure.

To set the initial injection lift Δl, after adjusting the main injection valve opening pressure as described above, attach the dial gauge to the holder main body 3, align the position of the male threaded member 9 with the zero point of the dial gauge, and then and raise the male threaded member 9 until the pointer of the dial gauge points to the predetermined initial injection lift Δl,
This is done by tightening the lock nut 11 at that position and fixing the male threaded member 9.

The initial injection and main injection valve opening pressures and the initial injection lift are adjusted and set using the method described above.The valve opening pressure during main injection is set by contacting the lower end of the push rod 6a with the upper end of the first movable spring seat 4. When this is done, care must be taken to ensure that the lower surface of the second movable spring seat 6 and the male threaded member 9 do not separate. If you set the valve opening pressure during main injection without noticing the separation, the male threaded member 9 that was separated will come into contact with the second movable spring seat 6 when setting the next initial injection lift amount, and the second movable spring seat 6 will This is an extremely difficult task that requires careful attention because there is a problem in that the main injection valve opening pressure changes due to changes in the set load. Furthermore, regarding the initial injection lift amount setting, there is a slight dimensional tolerance between the female threads of the holder main body 3 and the female threads of the lock nut 11 that are screwed into the male threaded member 9, causing the threads to fall. Moreover, since the value of the initial injection lift Δl is as small as about 0.1 mm, it is difficult to accurately set the interval of the initial lift Δl by rotating the male threaded member 9 due to the collapse of the thread. It is extremely difficult.

The present invention has been made in order to solve many of the problems in the adjustment work of the conventional fuel injection valve holder described above, and it is possible to adjust the settings of the initial injection valve opening pressure, the main injection valve opening pressure, and the initial injection lift, respectively. To provide a fuel injection valve holder which can be adjusted individually and whose adjustment work is simplified.

In order to achieve this object, in the present invention, a nozzle body is attached to one end of the holder body, a first movable spring seat is brought into contact with the nozzle needle valve, and a first movable spring seat is provided between the first movable spring seat and the holder body. A nozzle spring is disposed above the first movable spring seat to set the initial valve opening pressure, and a second nozzle spring is installed above the first movable spring seat at a distance equivalent to the initial injection lift.
A lower end of the push rod of the movable spring seat is disposed, and a second nozzle spring is disposed between the second movable spring seat and the holder main body, and after the initial injection lift of the nozzle needle valve, the first In the fuel injection valve holder configured to set the main injection valve opening pressure by the resultant force of the nozzle spring and the second nozzle spring, a screw hole and a fitting hole are sequentially formed from the other end side of the holder main body. A second movable spring seat support member that supports the second movable spring seat is removably fitted into the uppermost part of the fitting hole, and the second movable spring seat support member and the first nozzle spring are connected to each other. A first step for setting the initial valve opening pressure between
A nozzle spring adjustment shim is provided, and a hollow male threaded member is screwed into the screw hole, and the head of the first movable spring seat when the nozzle needle valve is seated extends from the upper end of the second movable spring seat support member. The length _{l 2 of} the push rod portion of the second movable spring seat is slightly larger than the length l 1 of the second movable spring seat, and the spring seat portion of the second movable spring seat is disposed on the male threaded member. An adjustment member for adjusting the pressing force of the second nozzle spring is provided, and an initial injection lift adjustment shim is inserted between the lower surface of the second movable spring seat and the upper surface of the second movable spring seat support member. That is.

With the above configuration, the first nozzle spring has the same configuration as the conventional one, so it can be adjusted independently as before.

In addition, the initial injection lift adjustment shim that sets the initial injection lift amount has a length l ₁ from the upper surface of the second movable spring seat support member to the head of the first movable spring seat when the needle valve is seated, and 2. The difference between the length of the push rod part of the movable spring seat _l2 , that is, _l2 - _l1 = h, is automatically measured, and the value obtained by adding the initial injection lift Δl to this h,
That is, let h+Δl=t be the thickness of the shim.

Next, the main injection valve opening pressure is set based on the main injection valve opening pressure at the time of adjustment, which has been calculated in advance with the initial injection lift adjustment shim removed.
This can be done by adjusting the adjustment member to change the pressing force of the second nozzle spring. After that, an initial injection lift adjustment shim is interposed between the upper surface of the second movable spring seat support member and the lower surface of the second movable spring seat to adjust the initial injection valve opening pressure, main injection valve opening pressure, and initial injection lift. The overall adjustment is completed by making each amount adjustment independently.

As described above, according to the configuration of the present invention, each adjustment can be performed independently and extremely easily and accurately.

Next, embodiments of the present invention will be described with reference to FIGS. 2 to 5. FIG. 2 is a longitudinal cross-sectional view of a fuel injection valve showing an embodiment of the present invention. In the figure, 20 is a holder main body, and a nozzle main body 21 is attached to the tip of the holder main body with a nozzle nut 22.
A plurality of injection holes 21a are formed at the tip of one. A nozzle needle valve 2 is provided in the inner hole of this nozzle body 21.
3 is slidably fitted, the tip of the nozzle needle valve 23 abuts the valve seat 21b, and a head 23a is formed at the upper end. The holder main body 20 has a screw hole 20a' toward the tip and first to fifth fitting holes 20a, 20b, 20c, 20d whose diameters are sequentially reduced.
20e are coupled. In FIG. 2, the head 23a of the nozzle needle valve 23 is fitted into the fourth fitting hole 20d at the second stage from the bottom via the fifth fitting hole 20e. Further, a push rod 24a of the first movable spring seat 24 is slidably fitted into the fourth fitting hole 20d. The first movable spring seat 24 receives the head 23a of the nozzle needle valve 23 at its lower end, and the head 24b at its upper end is fitted into the third fitting hole 20c.

In FIG. 2 of the holder main body 20, the first field fitting hole 20a at the uppermost stage and the second fitting hole 20 at the next stage.
b includes a flange 25a that fits into the first fitting hole 20a, and a body portion 2 that fits into the second fitting hole 20b.
A second movable spring seat support member 25 integrally formed with the second movable spring seat support member 25 is fitted so that the respective step portions are in contact with each other and can be inserted and removed from above. A flat part 25c is formed on the upper surface of the second movable spring seat support member 25, and an inner hole 25d is bored in the axial center of the flat part 25c.
A push rod 26a of the second movable spring seat 26 is slidably inserted into the second movable spring seat 26, and a shim 27 for adjusting the initial injection lift is inserted into the lower surface of the second movable spring seat 26, and the second movable spring seat support member 25 It is supported by the flat part 25c. Here, the length l ₂ of the push rod 26a is determined from the flat part 25c of the second movable spring seat support member 25 to the head part 2 of the first movable spring seat 24 in the seated state.
The distance l to the top surface of 4b is set slightly larger than ₁ . The flat portion 25c of the second movable spring seat support member 25 is fixed in position by being held down by the hollow male screw member 28 screwed into the screw hole 20a', so that the flat portion 25c is fixed in position. is formed. The lower end surface of the second movable spring seat support member 25 connects the upper end of the first nozzle spring 30 housed in the third fitting hole 20c of the holder main body 20 via the first nozzle spring adjustment shim 29. and applies a pressing force to the first movable spring seat 24. The second movable spring seat 26 is located at a hollow portion 28 of the male screw member 28.
a and inserted into the hollow part 28a.
A pressing force is applied to the second nozzle spring 31 by receiving the lower end of the nozzle spring 31, and the second nozzle spring adjusting screw (adjustment Element)
32 adjusts the pressing force, and the position of the second nozzle spring adjustment screw 32 is fixed by tightening a lock nut 33 screwed therein.

Male thread member 28 at the upper end of the holder main body 20
is covered by a cap nut 36 screwed thereon. A fuel passage 38 for guiding fuel from a fuel injection pump (not shown) to a pressurized space 37 of the nozzle body 21 is provided on the sides of the holder body 20 and the nozzle body 21 .

The pressing force of the second nozzle spring 31 can be adjusted by screwing a cap screw 34 onto the upper end of the male threaded member 28, and inserting a second nozzle spring adjusting shim 35 on the inner surface of the cap screw 34, as shown in FIG. A so-called shim adjustment method may also be used.

In the fuel injection valve holder of the present invention having the above configuration, the fuel pumped from the fuel injection pump is fed under pressure to the pressurized space 37 of the nozzle body 21 through the fuel passage 38, and the pressure inside the pressurized space 37 is reduced to the first nozzle. When the initial injection valve opening pressure set by the spring 30 is exceeded, the nozzle needle valve 23 begins to lift, and when it is displaced by the initial injection lift Δl, the head 24b of the first movable spring seat 24 moves to the push rod of the second movable spring seat 26. 26a, and at the valve opening pressure and lift amount in this state, initial injection is performed at a low injection rate. When the fuel pressure further increases and exceeds the combined force of the pressing force of the first nozzle spring 30 and the pressing force of the second nozzle spring 31, the nozzle needle valve 23 is moved via the first movable spring seat 24 to the second movable spring seat 26. Press the second nozzle spring 3
1 is compressed and lifted, the nozzle needle valve 23 is displaced by the maximum lift 1, and main injection is performed at a high injection rate.

Next, a method for adjusting the fuel injection valve holder will be explained with reference to FIGS. 4 and 5. First, the initial injection valve opening pressure is set by screwing the hollow male threaded member 28 into the holder main body 20, fixing the second movable spring seat support member 25, and forcefully feeding fuel from the fuel passage 38. The first nozzle spring adjustment shim 29, whose thickness is selected to achieve the valve opening pressure, is inserted into the second nozzle spring adjusting shim 29.
This is done by inserting it between the lower surface of the movable spring seat support member 25 and the first nozzle spring 30.

Next, to set a predetermined initial injection lift Δl,
Male screw member 28 and second movable spring seat support member 25
from the holder main body 20, and put it in another jig.
When assembled in the state shown in the figure, the push rod 26a of the second movable spring seat 26 is inserted into the inner hole 25d of the second movable spring seat support member 25, and the lower surface of the second movable spring seat 26 is attached to the second movable spring seat support member 25. The lower end surface of the male threaded member 28 is brought into contact with the flat part 25c of the second movable spring seat support member 25 while the male screw member 28 is in contact with the flat part 25c of the second movable spring seat support member 25. On the other hand, the screw hole 28b in the inner space of the male threaded member 28
The male screw member 39 of the dial gauge 40 is screwed onto the dial gauge 40, the measuring rod 40a of the dial gauge 40 is brought into contact with the head 26b of the second movable spring seat 26, and the pointer of the dial gauge 40 at this time is set to zero. In this state, when the second movable spring seat support member 25 and the male screw member 28 are attached to the holder body 20 as shown in _FIG. is the second movable spring seat support member 2
Since the distance from the flat part 25c of No. 5 to the upper surface of the head 24b of the first movable spring seat 24 in the seated state is slightly larger than l ₁ , the push rod 26a is connected to the top surface of the head 24b of the first movable spring seat 24. the second
The movable spring seat 26 is slightly spaced apart from the upper surface of the second movable spring seat support member 25, that is, the flat portion 25c forming the bottom surface of the screw hole 20a'. At this time, the indicated value h of the pointer of the dial gauge 40 is read. That is, if the length of the push rod 26a is _l2 , the value of h is the difference between _l2 and _l1 , that is, _l2 - _l1 =h. Therefore, to set the initial injection lift Δl, the second movable spring seat 2
The initial injection lift adjustment shim 27 having a thickness of h+Δl=t may be interposed between the lower surface of the spring seat 6 and the flat portion 25c of the second movable spring seat support member 25.

Next, to set the main injection valve opening pressure, use the initial injection lift adjustment shim 27 selected as described above.
Remove and assemble this fuel injector. By doing this, the head 24b of the first movable spring seat 24
The lower end of the push rod 26a of the second movable spring seat 26 is in contact with the upper surface, and the second movable spring seat 26 is spaced apart from the flat portion 25c of the second movable spring seat support member 25 by the distance h. In this state, the second nozzle spring adjustment screw 32 is adjusted to change the spring force of the second nozzle spring 31 to set a predetermined main injection valve opening pressure, but the actual main injection valve opening pressure is determined by the first nozzle spring. This is the sum of the spring forces of both springs 30 and 31 when both springs 30 and 31 are compressed by the initial injection lift amount Δl from this state. Therefore, the main injection valve opening pressure during adjustment that is set at this time is lower than the actual main injection valve opening pressure as the sum of both spring forces when the first nozzle spring 30 and the second nozzle spring 31 are extended by Δl. Set. The main injection valve opening pressure during this adjustment can be calculated in advance with sufficient accuracy. In addition, in the case of the shim adjustment shown in FIG.
This is done by interposing it between the cap screw 34 and the cap screw 34.

Thereafter, the male threaded member 28 is removed from the holder main body 20, and the preset initial injection lift adjustment shim 27 is attached to the flat part 2 of the second movable spring seat support member 25.
5c and the lower surface of the second movable spring seat 26, adjustment of the initial injection valve opening pressure, the main injection valve opening pressure, and the initial injection lift amount is completed. As described above, each adjustment can be performed independently.

As detailed above, according to the present invention, the initial injection valve opening pressure can be set by interposing the first nozzle spring adjusting shim on the lower surface of the second movable spring seat support member by selecting the thickness of the first nozzle spring adjusting shim. Therefore, it can be done easily and accurately. The initial injection lift Δl is determined by the length _l2 of the push rod of the first movable spring seat and the distance l from the top surface of the second movable spring seat support member to the top surface of the head of the first movable spring seat in the seated state. Since the difference h from ₁ can be automatically measured,
This can be done easily and accurately by selecting an initial injection lift adjustment shim with a thickness of h+Δl and interposing it between the lower surface of the second movable spring seat and the upper surface of the second movable spring seat support member. can. Furthermore, the setting of the main injection valve opening pressure is performed by removing the initial injection lift adjustment shim and adjusting the pressure by calculating in advance with the push rod of the second movable spring seat in contact with the head of the first movable spring seat. If the second nozzle spring is adjusted based on the main injection valve opening pressure, the main injection valve opening pressure can be easily obtained as a set load that is a combination of the first nozzle spring and the second nozzle spring. Furthermore, even if adjustments are made to other parts after adjusting each part, the adjustments made before will not be disturbed, making the adjustment extremely easy.

[Brief explanation of drawings]

FIG. 1 is a vertical cross-sectional view of a conventional fuel injection valve, FIG. 2 is a vertical cross-sectional view of a fuel injection valve holder showing one embodiment of the present invention, and FIG. 3 is a vertical cross-sectional view of a fuel injection valve holder showing another embodiment of the present invention. 2
A sectional view of the nozzle spring pressing force adjusting means, and FIGS. 4 and 5 are longitudinal sectional views showing a method of setting the initial injection lift. 20... Holder body, 20a'... Screw hole, 20a,
20b, 20d, 20e... Fitting hole, 21... Nozzle main body, 23... Nozzle needle valve, 24... First movable spring seat, 24b... Head, 25... Second movable spring seat support member, 26... Second movable spring Seat, 26a... Push rod (push bar part), 27... Initial injection lift adjustment shim, 28
...Male thread member, 29...First nozzle spring adjustment shim, 30...First nozzle spring, 31...Second nozzle spring, 32...Second nozzle spring adjustment screw (adjustment member).

Claims (1)

[Claims] 1 Attach the nozzle body to one end of the holder body,
A first movable spring seat is brought into contact with the nozzle needle valve, and a first movable spring seat is placed between the first movable spring seat and the holder main body.
A nozzle spring is disposed to set an initial valve opening pressure, and the lower end of the push rod of the second movable spring seat is disposed above the first movable spring seat at a distance equivalent to the initial injection lift; A second nozzle spring is disposed between the movable spring seat and the holder main body, and the main injection valve is opened by the combined force of the first nozzle spring and the second nozzle spring after the initial injection lift of the nozzle needle valve. In the fuel injection valve holder configured to set the pressure, a screw hole and a fitting hole are sequentially formed from the other end side of the holder main body, and the second movable spring seat is provided at the top of the fitting hole. a first nozzle spring adjustment for removably fitting a second movable spring seat support member supporting the second movable spring seat support member and setting the initial valve opening pressure between the second movable spring seat support member and the first nozzle spring; a hollow male screw member is screwed into the screw hole, and a hollow male screw member is screwed into the second screw hole.
From the length _l1 of the upper end of the movable spring seat support member to the head of the first movable spring seat when the nozzle needle valve is seated, the length of the push rod portion of the second movable spring seat
l ₂ is slightly larger, the spring seat portion of the second movable spring seat is disposed within the male threaded member, an adjustment member for adjusting the pressing force of the second nozzle spring is provided in the male threaded member, and the second A fuel injection valve holder, characterized in that an initial injection lift adjustment shim is inserted between the lower surface of the movable spring seat and the upper surface of the second movable spring seat support member.