JPH03222860A - Pressure intensifying type fuel injection valve - Google Patents

Abstract

PURPOSE:To shorten a fuel injection period of time by installing a pressure valve, for partitioning off a pressure chamber, at the time of a plunger chamber of an injection on-off valve, while interconnecting the pressure chamber to an accumulator chamber where this injection on-off valve is housed, via a pressure inflow means, and making it possible to set the valve closing pressure highish. CONSTITUTION:The base side of a plunger 45 partitioning a plunger chamber 49 at the end face is projected to the inside of a sliding hole 69 formed in a nozzle head 53, and the end part is clamped to a booster piston 71. A pressure intendifying chamber 75 partitioned off by this booster piston 71 is made interconnectible to a fuel inlet 57 via a three-way solenoid valve 77. In addition, at the side of a block 47 of a nozzle body 91, there is formed with an accumulator chamber 103 being interconnected to the plunger chamber 49 via a bypass passage 101. A needle valve 107 or an injection on-off valve is fitted in this accumulator chamber 103 and an injection fuel passage 105. In this case, a pressure valve 113 is installed in an upper part of the needle valve 107, and a pressure chamber 115 being partitioned off by this pressure valve is interconnected to the accumulator chamber 103 via a pressure feeding valve 117.

Description

[Detailed description of the invention]

[Object of the Invention (Industrial Field of Application) The present invention relates to a pressure boosting fuel injection valve used in, for example, a diesel engine, which is provided with a pressure boosting chamber for boosting the pressure of fuel for injection. (Prior art) Since a diesel engine injects fuel into the air inside the cylinder under high pressure and high temperature to ignite it, a higher pressure is applied to the injected fuel to promote atomization of the fuel t1 and fuel injection. It is desirable to try to shorten the period, and one way to deal with this is to shorten the period. For example, there is a pressure-increasing plunger type fuel injection valve as shown in FIG. This fuel injection valve is of a pressure increasing plunger type that pressurizes fuel using hydraulic pressure, and when the plunger l is lowered, the accumulator valve 5 is pushed down via the fuel in the plunger chamber 3, and the fuel in the plunger chamber 3 is The fuel is force-fed to the pressure storage chamber 9 of the nozzle body 7Wi, and then when the needle valve 11 rises due to a pressure drop in the 7-lunger chamber 3, fuel is injected from the injection hole 15 at the tip of the nozzle tip 13 into a cylinder (not shown). A pressure increase piston 17 is disposed at the end of the pressure increase plunger 1 opposite to the plunger chamber 3.
One pressure intensification chamber is formed on the opposite side of the plunger 1. The pressure boosting chamber 19 is supplied with fuel through a three-way solenoid valve 21.
It is possible to communicate with 3. The three-way solenoid valve 21 is the pressure booster chamber 1
In addition to putting the two and the fuel inlet LI23 into communication,
The chamber 19 and the fuel release D 25 are brought into communication. Also,
The fuel tank 1123 can communicate with the plunger chamber 3 through the fuel passage 27, and the fuel tank 1 passage 27 can communicate with the fuel tank 1123.
．． A check valve 29 is provided which allows flow only to the plunger chamber 3 from the plunger chamber 23. The fuel tank 31 is pumped up from the fuel tank 31 by the feed pump 33 and the pressure is regulated.
−) is supplied. 37 is a pressure gauge and 39 is an accumulator. The above three-way solenoid valve 21 has one pressure boosting chamber and fuel release (-125
When these are brought into communication, the fuel sent by the foot pump 33 is supplied from the fuel inlet 23 to the plunger chamber 3 through the fuel passage 27. On the other hand, when the three-way solenoid valve 21 brings the fuel inlet 23 and the pressure boosting chamber 19 into communication, the fuel sent by the foot pump 33 is guided to one pressure boosting chamber. When fuel is introduced into one pressure boosting chamber, the pressure boosting piston 17 is pushed down together with the plunger 1, and the fuel in the plunger chamber 3 is transferred between the pressure receiving parts of the pressure boosting piston 17 and the plunger 1. The pressure is increased by the area, pushing down the accumulator valve 3, and the pressure is fed to the pressure accumulating chamber 9. When the pressure in the pressure accumulator chamber 9 and the pressure in the plunger chamber 3 are balanced, the accumulator valve 5 is closed by the spring 41, and the pressure accumulator chamber 9 is sealed. Here, the three-way solenoid valve 21 has one pressure intensifying chamber and one fuel release chamber [''2].
5 is brought into communication again, the pressure within one pressure increase chamber is released to atmospheric pressure, and the pressure increase piston 17 is pushed by the spring 43 and rises by one. At the same time, the pressure within the plunger chamber 3 also decreases to the pressure supplied by the foot pump 33. At this time,
If the pressure in the pressure accumulator 9, the pressure in the plunger chamber 3 and the pressure in the plunger chamber 3 exceed the force that tries to close the 21-torparf 11, the 21-torparf 11 closes and the fuel in the accumulator 9 is released. It is injected from the t+B3 injection hole 15. When the fuel L1 is injected, the pressure in the pressure accumulation chamber 9 begins to decrease, and when this decreasing pressure and the pressure in the spring 41 and the plunger chamber 3 are balanced, the needle valve 11 opens. Close and end injection. After that, repeat the above steps. (Problem to be Solved by the Invention) By the way, in such a conventional pressure increase type fuel injection valve, the so-called valve closing pressure when the needle valve 11 closes and the fuel f=1 injection ends is the pressure in the plunger chamber. It is determined by the balance between the supply pressure to the plunger chamber 3, the force of the spring 41, and the force due to the pressure in the pressure accumulator chamber 9. Since it is the same as the supply pressure to one chamber, the valve closing pressure determined by this supply pressure is considerably lower than the pressure in the pressure accumulation chamber 9 during high-pressure injection, and therefore the pressure in the pressure accumulation chamber 9 after injection is It takes time for the needle valve 11 to close when the pressure drops to the valve closing pressure, and although high-pressure injection is possible, the injection period at that time is not sufficiently shortened, and as a result, the combustion period increases. Combustion, exhaust performance, fuel efficiency, etc. will deteriorate. Therefore, the purpose of this invention is to sufficiently shorten the injection period while making high-pressure fuel injection possible. Means for Solving) In order to solve the above-mentioned problems, the present invention provides a plunger chamber in which fuel for injection is supplied to the tip side of a reciprocally movable plunger, while a plunger chamber is provided in the base side of the plunger. A pressure boosting chamber is provided to which pressure boosting fuel is supplied to increase the pressure of the plunger chamber, and a pressure accumulating chamber that can communicate with the plunger chamber and is filled with injection fuel is biased in the valve closing direction by an elastic means. In a pressure booster fuel injection valve provided with an injection on-off valve, a pressure valve that forms a pressure chamber between the injection on-off valve and the injection on-off valve is provided on the plunger chamber side of the injection on-off valve. A pressure supply passage that enables communication with the pressure accumulation chamber is provided, and a pressure inflow means is provided in the pressure supply passage for causing the fuel in the pressure accumulation chamber to flow into the chamber at a predetermined pressure after fuel injection. ((For Ya) When 1:・l of fuel is supplied to the pressure intensifying chamber, the fuel being supplied to the plunger chamber increases the j+ force and flows into the pressure accumulating chamber and into the pressure chamber. Incoming fuel f-1
While the pressure in the pressure inflow means is maintained at a predetermined level, the pressure in the pressure accumulator becomes high. The pressure in the plunger chamber is then reduced, and the pressure in the accumulator chamber is increased by the elastic means and the pressure in the plunger chamber.

When the force that tries to close the 10 injection on-off valve is turned by 1, the 110 injection on-off valve closes and the fuel in the pressure accumulation chamber is injected by 11n. During fuel f'4'C injection, the pressure in the pressure storage chamber decreases, and when this pressure becomes equal to the predetermined I+ force in the pressure chamber, the injection on-off valve is activated by the action of the elastic means. Promptly speak ['' only at By setting the pressure from the pressure accumulation chamber that supplies the pressure chamber, that is, the valve closing pressure, to be higher than the supply pressure to the plunger chamber, this jump timing can be made earlier, and the injection period can be shortened.9 (Example) Embodiments of the present invention will be described below with reference to the drawings.
The I'm injection valve is a pressure booster plunger type that pressurizes the fuel using hydraulic pressure used in diesel engines.
The plunger 45 is provided so that its distal end side can slide within a block 47, and four plunger chambers are formed surrounded by the end face of the plunger 45 and the block 47. The four plunger chambers have fuel passages 51 formed in the block 47.
．． A check valve 52 provided in the middle of the fuel passage 51. It is possible to communicate with the fuel inlet 1] 57 via a fuel pt passage 55 formed in the nozzle throat 53. The fuel inlet [1157] is connected to one end of the fuel pipe 59, and the other end of the five fuel pipes is connected to a fuel tank 63 with a feed pump 61 provided in the middle. 65 is pressure adjustment valve 1 (56
is a pressure gauge, and 67 is an accumulator. The base side of the plunger 45 on the opposite side from the four plunger chambers protrudes into a sliding hole 69 formed in the nozzle nut 53, and a base end side of the plunger 45 comes into contact with the six sliding holes. A cap-shaped pressure increase piston 71 is slidably housed. The pressure increasing piston 71 is biased in the direction by a spring 73 provided on the plunger 45 side, and a pressure increasing chamber 75 is formed on the opposite side of the pressure increasing piston 71 from the spring 73. There is. The pressure boosting chamber 75 can communicate with a fuel inlet 157 via a three-way solenoid valve 77 in the middle. Three-way electromagnetic fr77
When the seven solenoids are energized or de-energized, the Hall valves 83 and 85 provided at the tip and middle of the lot 81 move, and the pressure intensifying chamber 75 is brought into communication with the combustion chamber 157. , fuel t-+ open 1'J 87 can be switched.
is connected to the fuel tantalo 3. Plunger 4
The nozzle body 91 is located below the block 47 on which the nozzle 5 slides.
is attached by a nozzle nut 93, and a nozzle tip 95 is attached to the lower side of the nozzle body 91 by a retainer 97. The plunger chamber 4 is located on the block 47 side of the nozzle body 91.
A pressure accumulating chamber 103 is formed in the nozzle body 9 and a pressure accumulating chamber 103 that can communicate through a side passage 101 of the accumulator valve 99 is formed.
On the nozzle tip 95 side of No. 1 and on the nozzle tip 95, an 11^ injection fuel flow path 105 communicating with the pressure accumulation chamber 103 is formed. A needle valve 107 as an injection opening/closing valve is housed in the pressure accumulation chamber 103 and the injection fuel flow path 105 so as to be movable up and down. 97a can be opened and closed. At the end of the four plunger chambers of the needle valve 107,
The nine accumulator valves are slidably fitted into the accumulator valve 99 and the needle valve 1.
Flange 109 formed inside the pressure accumulation chamber 103 of 07
A spring 111 as an elastic means is interposed between the two and biases the nine accumulator valves toward the four plunger chambers. On the four plunger chamber sides of the nine accumulator valves, a pressure valve 113 is slidably disposed to face one end of the needle valve 107. pressure valve 11
A flange 114 that is housed in a four part 99a formed in the accumulator valve 99 is mounted on the end portion of the four plunger chambers that protrudes from the nine accumulator valves of No. 3. The flange 114 has a triangular shape. The three apex portions are formed into a circular arc shape, and the circular arc portions are brought into sliding contact with the inner circumferential surface of the recessed portion 99J1, and a through hole 114a is provided in the center. The opposing portions of the pressure '/T 113 and the needle valve 107 have arcuate cross sections, and a pressure chamber 115 is formed between them. The block 47 and the nozzle nut 93 on the four sides of the plunger chamber are provided with a pressure supply valve 117, which serves as a pressure inflow means for supplying the pressure in the pressure accumulation chamber 103 to the pressure chamber 115 at a predetermined pressure. A solenoid valve 119 is also installed to release the pressure inside the pressure chamber 115 which is maintained at a predetermined pressure. The passage 121a in the valve body 121 of the solenoid valve 119 has a professional
It communicates with the pressure chamber 115 through pressure supply passages 123 and 125 formed in the plug 47 and nine accumulator valves, respectively. Pressure supply passage 123 and j+
The connecting portion with the force supply passage 125 is a concave portion 478 on the second block 47 side, and a concave portion 478 on the aluminum block 47 side.
By forming nine convex portions that fit tightly and slidably into 7a, the space and l-mulator valve 99
Even if the pressure supply passages 123 and 125 are lowered, the four plunger chambers are prevented from communicating with each other. Valve body 1
21 can be moved to the right in FIG. 1 by energizing the solenoid 127, thereby opening the passages 1', 2]
, n can be opened to the fuel tank 63 via the fuel pipe 129. The pressure supply valve 117 is located between a pressure supply passage 131a formed in the block 47 communicating with the pressure supply passage 123 and a pressure supply passage 131b formed in the block 47 communicating with the side passage 101. Interposed valve body 135
．． Adjustment 137. It is composed of a spring 139 that is interposed between the valve body 135 and the adjustment screw 137 and urges the valve body 135 to the left in FIG. 1, and the pressure supply passage 131b
The internal passage 135a of the valve body 135, which is always in communication with the pressure supply passage R131a, can be communicated with the pressure supply passage R131a when the -f+ body 135 is moved to the left by the spring 139. Here, the pressure inside the pressure accumulation chamber 103 when the valve body 135 moves to the right against the urging force of 13 springs is 500 k
g f ,/c rn '. Next, the operation of the pressure increase type fuel injection valve configured as described above will be explained using FIGS. 2 to 6. First, the three-way solenoid valve 77 is energized and the rod 81 is moved to the right in the figure so that the pressure boosting chamber 75 and the fuel t4 open II 87 are in communication. , fuel piping 59. The fuel is supplied to the plunger chamber 49 through the inlet 57 and the fuel passage 55.51. Next, when the three-way solenoid valve 77 is energized and the rod 81 is moved to the left in the figure so that the fuel inlet 57 and the pressure intensifying chamber 75 are in communication, the fuel ( The fuel is guided to the pressure boosting chamber 75 through the fuel pipe 59 and the fuel input 1'+ 57. When the fuel is guided to the pressure boosting chamber 75, the pressure boosting piston 71 is moved against the spring 73 by the plunger 45. The pressure inside the four plunger chambers reaches an extremely high pressure (e.g. 3000 kg r/
c:rn2). Accordingly, the 1-mulator valve 99 is pushed down against the spring 111, and the fuel in the four plunger chambers flows into the pressure accumulation chamber 103 through the side passage 101, and at the same time, the fuel in the pressure supply passage 131b
, valve body passage Rr135a, pressure supply passage 131a,
123, 125 into the pressure chamber 115 (second
(see figure). During this process, the fuel pressure on the pressure accumulation chamber 103 side increases to 500
When it reaches k g f / cr n', the valve body]
35 moves to the right against the spring 139 and moves to the pressure accumulation chamber 10.
3 and the pressure chamber 115 are shut off, and the pressure in the pressure accumulation chamber 103 and the pressure chamber 115 is maintained at the above-mentioned 500 kgr/C: m 2 (see FIG. 3). That's me, the pressure inside the pressure accumulator chamber 103 has further increased to an ultra-high pressure (
For example, when the pressure reaches 3000 kg f /<:rn2), the nine accumulator valves rise and become idle as shown in FIG. 3, and the plunger chamber 49 and the pressure accumulation chamber 103 are cut off. Here, when the three-way solenoid valve 77 is operated and the pressure increase chamber 75 and the fuel release valve [195] are communicated again, the pressure inside the pressure increase chamber 75 is released completely, and the pressure increase valve 75 is opened to the fuel release valve [195]. The plunger 71 is pushed by the spring 73 and decreases by -1 along with the plunger 45. In response to this (in the old days), the feedability of the feed 7 in the runner chamber 49 and the feedability of the suship ( ) 1 gradually became OK. At this time, if the force in the pressure accumulator 103 is 1.1 times the force trying to break the needle valve 107 due to the spring 111 and the pressure in the plunge chamber 49, then
The needle half 107 and the pressure valve 113 go -IM and close, and the fuel 1'4 in the pressure accumulating chamber 103 is injected with I'i'+ TL 97 ;I color 11n (see Figure 11).
. At this time, one gradient in the pressure accumulation chamber 103 is 3000 kg, f7
cm' becomes the fuel 110 injection II-. When fuel is injected, the pressure inside the pressure accumulation chamber 103 gradually decreases, and the pressure supply passage 13 communicating with the pressure accumulation chamber 103 gradually decreases.
The pressure at l b also decreases, and this pressure becomes 500 kgf/cm.
2, the valve body 135 moves to the left as shown in FIG. 5, thereby communicating the pressure supply passages 131a and 131b. As a result, the pressure in the pressure chamber 115 becomes the same as the pressure inside the pressure accumulation chamber 103, and at this time, the needle valve 107 quickly lowers and closes only by the biasing force of the spring 111 while keeping the pressure valve 113 pressed, and the injection is stopped. finish. At this time, the pressure inside the pressure chamber 115 and the pressure accumulation chamber 103 is 500
kgr/crn" becomes the valve closing pressure. When the injection is finished, the feed pump 61 is turned on as shown in Fig. 6.
The fuel V for the next injection flows into the four plunger chambers. At this time, the pressure inside the pressure chamber 115 remains elevated to the valve closing pressure, so by energizing the solenoid 127 of the solenoid valve 119, the valve body passage 121a and the fuel pipe 129 are communicated, and the pressure chamber 115 is opened. It is opened to atmospheric pressure, and the released fuel is returned to the fuel tank 63. In this state, the storage j1: chamber 103 falls to a high pressure slightly lower than the jump pressure. After that, when the solenoid 127 is energized or stopped and the solenoid valve 117 is closed, the state shifts to the state in which the four plunger chambers are pressurized as shown in FIG.
Repeat the bipedal movement. FIG. 7 shows the injection pressure and valve closing pressure and the corresponding fuel injection rate and injection period in the conventional example, and No. 814 is 1. The injection pressure and valve closing pressure in the example described above, and the corresponding fuel i
t l'a ejection rate and injection duration are shown. The closing pressure in the embodiment described above is 200 kg f/cm" (from the FM system). Supply j1-to the river'!1) Higher 500 kg
r/c: set to m', which is good for the descent of the plunger 45).
g f y′c m 2 to 3000 kg [(・ITI
'It's expensive. As a result, the 1η valve timing that ends after fuel injection is either the pressure inside the pressure accumulator 103 or 500.
pressure chamber with kg f' 7 cm 2)
:It is faster because it only takes until the internal pressure reaches 3. Therefore, the injection period can be changed to 1 while keeping the fuel injection amount the same as in 1.
, 1 to t2 can be shortened. This will improve combustion and exhaust performance and significantly reduce fuel consumption. Moreover, since the valve closing pressure can be set by adjusting the head 119 of the pressure supply valve 117, the injection period can also be set accordingly. In addition, the valve closing operation described in - is carried out only by the biasing force of the spring 111 when the pressure inside the pressure storage chamber 103 drops to the pressure inside the pressure chamber 115, so the valve closing operation is quick, and therefore the combustion It can prevent afterburn caused by fuel dripping, which has a negative impact on the fuel. FIG. 9 shows a second embodiment of the invention. In this embodiment, the solenoid valve 117 shown in FIG.
3 is also used. The configuration of the pond is similar to that of the first embodiment. The rod-shaped valve 143 has a solenoid 145 and a solenoid 14.
5, the rod-shaped valve body 147 moves in the left-right direction in the figure.
It is composed of. The rod-shaped valve body 147 includes a main passage 151 communicating with the fuel inlet 149, first and second communication passages 153 and 155 provided perpendicularly to the middle and end of the main passage 151, and a solenoid 1 connected to the main passage 151.
Third and fourth communication passages 157 and 15 provided on the 45 side
9 is formed. In the state shown in FIG. 9, the second communication passage 155 is
At this time, fuel is supplied to the pressure increase chamber 161 and the four plunger chambers are pressurized. On the other hand, when the rod-shaped valve body 147 moves leftward from this state, the first
The communication passage 153 communicates with the fuel passage 163, and the third communication passage 1
57 connects the pressure boosting chamber 161 and the combustion chamber 57 to communicate with each other. At this time, new fuel is supplied to the four plunger chambers through the fuel t1 passage 163. Then, when the rod-shaped valve body 147 is further moved to the left, the fourth communication passage 159 communicates the flow passage 167 connected to the pressure chamber 115 and the fuel release port 165. As a result, the pressure within the pressure chamber 115, which has increased by 1'' to the valve closing pressure, is reduced. In this embodiment, as in the first embodiment, the injection period can be sufficiently shortened while maintaining the desired injection amount while sufficiently atomizing the fuel with high 1+ injection, improving combustion and exhaust performance and reducing fuel consumption. This will result in a significant reduction. In addition, in this case, since the operation of reducing the pressure inside the pressure chamber 115 is made to function as the rod-like valve 143 that switches the pressure increasing chamber 161 between fuel input II 149 and fuel release 111 G 5, -F~, for the above pressure reduction This eliminates the need for a dedicated solenoid valve, which can reduce costs accordingly. [Effects of the Invention] As described below, according to the present invention, a pressure valve is provided on the plunger chamber side of the IQ Ikawa opening valve to form a pressure chamber between it and the injection opening/closing valve. A pressure supply passage is provided to enable communication between the pressure chamber and a pressure accumulation chamber in which the 11 injection volume valves which are biased in the valve closing direction by means are provided. Since the structure is provided with a pressure inflow means for causing the inside of the pressure accumulation chamber to flow into the pressure chamber at a predetermined pressure before and after the a injection, the pressure inside the pressure chamber set by the pressure inflow means can be set as the valve closing pressure. The valve pressure can be set higher regardless of the supply pressure to the plunger chamber, which allows the valve to close earlier, ensuring sufficient fuel atomization with high-pressure injection and a sufficient fuel injection period with a predetermined injection amount. It is possible to improve combustion and exhaust performance, and reduce fuel consumption.

[Brief explanation of drawings]

Fig. 1 is a sectional view of a fuel injection valve showing a first embodiment of the present invention, Figs. 2 to 6 are explanatory diagrams of its operation, and Fig. 7 is a change in valve closing pressure and injection pressure in a conventional example. FIG. 8 is an explanatory diagram showing the fuel injection rate and injection period according to changes in valve closing pressure and injection pressure in the first embodiment, and FIG. 1013 is a cross-sectional view of a fuel injection valve showing a second embodiment of the invention, and No. 1013 is a cross-sectional view of a fuel injection valve showing a JK conventional example. 45・Plunger 49...Plunger chamber 75...
Pressure boosting chamber 103... Pressure accumulating chamber 07... Neattle valve (injection on/off valve) 11... Spring (elastic means) 13... Pressure valve 115... Pressure chamber 17... Pressure supply valve (pressure inflow means) )23.125,131a,1
31b-・Pressure supply passage

Claims (1)

[Claims] A plunger chamber to which fuel for injection is supplied is provided on the tip side of the reciprocally movable plunger, while a pressure increasing chamber is provided at the base side of the plunger to which fuel for pressure increase is supplied to increase the pressure in the plunger chamber. A pressure accumulator chamber is provided, is capable of communicating with the plunger chamber, and is filled with the injection fuel,
In a pressure booster fuel injection valve provided with an injection on-off valve that is biased in the closing direction by an elastic means, a pressure chamber is provided between the injection on-off valve and the plunger chamber side of the injection on-off valve. A pressure valve is provided to allow communication between the pressure chamber and the pressure accumulation chamber, and a pressure supply passage is provided to allow the fuel in the pressure accumulation chamber to flow into the pressure chamber at a predetermined pressure after fuel injection. A pressure increase type fuel injection valve characterized by being provided with a pressure inflow means.