JP3463565B2 - Fuel injection device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection device, and more particularly to a fuel injection device having a variable opening area of injection holes.

[0002]

2. Description of the Related Art With the tightening of exhaust gas regulations, fine control of the fuel injection amount is required, and various fuel injection devices have been disclosed in which the injection hole area is variable. For example, in the device disclosed in Japanese Patent Laid-Open No. 62-248868, the area of the injection hole is changed by using a piezoelectric element, which complicates the structure and requires a device for controlling the current flowing through the piezoelectric element. In the device described in Japanese Patent Laid-Open No. 5-321780 and the device described in Japanese Patent Laid-Open No. 7-224739, the injection hole area is changed by changing the lift amount of the needle valve, and the needle valve is not pressed against the wall surface. It is necessary to stop at an intermediate position, but this is very difficult to do reliably. In the device described in Japanese Patent Application Laid-Open No. 5-321780 and the device described in Japanese Patent Application Laid-Open No. 7-224739, the nozzle hole area is changed by changing the lift amount of the needle valve, and precise machining and precise control are performed. Is required. The device described in JP-A-57-35155 and JP-A-8-35
Device disclosed in Japanese Patent Laid-Open No. 338341 and Japanese Patent Laid-Open No. 8-93.
In the device described in Japanese Patent No. 601, the area of the injection hole is changed by providing a rotary shutter outside the injection hole or rotating the needle valve, and complicated processing and precise control are required. In the device described in JP-A-59-180063 and the device described in JP-A-6-26416, a needle valve is provided in the needle valve and each needle valve is controlled separately. Therefore, complicated processing and complicated control are required.

[0003]

SUMMARY OF THE INVENTION In view of the above problems, it is an object of the present invention to provide a highly reliable fuel injection device having a variable injection hole area with a simple structure.

[0004]

[0005]

[0006]

[0007]

According to the invention of claim 1, the needle valve is movably arranged in the nozzle body at the tip of the valve body, and the needle valve seat portion is separated from the nozzle body seat portion to form the nozzle body. A fuel injection device for injecting fuel by injecting fuel to an injection hole formed on the downstream side of a nozzle body sheet part, in which the opening area of the inlet of the injection hole is large when the pressure of the introduced fuel is high. A fuel pressure responsive injection hole area adjusting member is provided for varying the opening area of the injection hole inlet according to the fuel pressure so that the opening area of the injection hole inlet becomes small when the fuel pressure is low. The injection hole area adjusting member is composed of an elastic member arranged at the tip of the inside of the nozzle body and expanding and contracting according to the fuel pressure, and a valve body arranged on the elastic member, and the fuel is introduced to the upper surface of the valve body. Was First, the valve element moves along the inner surface of the tip of the nozzle body where the inlet of the injection hole is formed in accordance with the fuel pressure to change the opening area of the inlet of the injection hole. Will be provided. In the fuel injection device configured as described above, the amount of contraction of the elastic member changes according to the fuel pressure, and along with that, the valve element moves along the inner surface of the tip of the nozzle body where the inlet of the injection hole is formed. The opening area of the inlet of the injection hole is changed, and when the pressure of the fuel is high, the opening area of the inlet of the injection hole is increased and a large amount of fuel is injected, and when the pressure of the fuel is low, the opening area of the inlet of the injection hole is increased. It is made small and a small amount of fuel is injected.

According to a second aspect of the present invention, there is provided the fuel injection device according to the first aspect, wherein the elastic member is made of an elastic resin. In the fuel injection device configured as described above, the contraction amount of the elastic member formed of the elastic resin changes according to the fuel pressure, and the valve body is attached to the tip of the nozzle body where the inlet of the injection hole is formed. By moving along the inner surface and changing the opening area of the inlet of the injection hole, when the pressure of the fuel is high, the opening area of the inlet of the injection hole is increased and a large amount of fuel is injected, and when the pressure of the fuel is low The opening area of the inlet of the injection hole is reduced, and a small amount of fuel is injected.

According to a third aspect of the invention, there is provided the fuel injection device according to the first aspect of the invention, wherein the elastic member is fuel filled between the valve body and the innermost tip portion of the nozzle body. . In the fuel injection device configured as described above, the volume of the fuel filled between the valve body and the innermost tip of the nozzle body changes according to the fuel pressure, and the valve body forms the inlet of the injection hole accordingly. The nozzle is moved along the inner surface of the tip of the nozzle body to change the opening area of the inlet of the injection hole, and when the pressure of the fuel is high, the opening area of the inlet of the injection hole is increased and a large amount of fuel is injected, When the fuel pressure is low, the opening area of the inlet of the injection hole is reduced and a small amount of fuel is injected.

According to the invention of claim 7, there is provided the fuel injection device according to the invention of claim 1, wherein the fuel pressure responsive injection hole area adjusting member is arranged in the needle valve. In the fuel injection device configured as described above, the fuel pressure responsive injection hole area adjusting member disposed in the needle valve has a large opening area at the entrance of the injection hole when the pressure of the fuel introduced into the entrance of the injection hole is high. Then, a large amount of fuel is injected, and when the fuel pressure is low, the opening area of the inlet of the injection hole is reduced and a small amount of fuel is injected.

[0011]

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a diagram showing the overall structure of a first embodiment of the fuel injection device of the present invention.
[Fig. 3] is an enlarged view of a tip portion. The valve body 100 is composed of a nozzle body 110, an intermediate portion 120, and a driving portion 130. In the nozzle body 110, the valve chamber 1
11 is formed, and the valve body 141 of the needle valve 140 and the first guide 142 move in the valve chamber 111.

The valve body 141 of the needle valve 140 has a first taper surface 146 and a second taper surface 147 having a larger inclination with respect to the central axis than the first taper surface 146. There is.

A recess 150 is formed at the tip of the tapered surface 112 of the valve chamber 111, and an elastic body 151 coupled to the recess 150 and a movable valve 152 having a U-shaped cross section.
Is provided. The elastic body 151 is made of resilient spring steel in the first embodiment.
A nozzle 113 having an inlet is formed at the boundary between the tapered surface 112 and the recess 150.

A first space 121 for slidably receiving a second guide 144 of a needle valve 140, which is connected to a first guide 142 via a connecting rod 143, is provided in the intermediate portion 120.
And a second space 122 that receives a spring 145 that biases the entire needle valve 140 toward the tip side is formed.
The fuel passage 124 guides the fuel sent through the fuel pipe 123 to the fuel passage 114 of the nozzle body 110 and also to the portion above the second guide 144 of the first space 121 via the communication passage 125. The fuel passage 126 guides a part of the fuel passing through a return passage, which will be described later, to the second space 122 and a portion of the nozzle body 110 above the valve chamber 111.

A solenoid 131 is arranged in the drive unit 130. The solenoid 131 generates a magnetic force when energized, and draws the relief valve 132 toward the solenoid 131 side. As a result, the outlet side of the communication passage 134 is opened, and the portion of the first space 121 of the intermediate portion 120 above the second guide 144 is communicated with the return passage 133, and the fuel remaining in the portion is discharged when the valve is closed. Since the magnetic force generated by the solenoid 131 is also acting on the needle valve 140, the magnetic force is attracted to the solenoid 131 side, the outlet side of the communication passage 125 in the intermediate portion 120 is blocked, and the fuel is supplied to the valve chamber 111 of the nozzle body 110. Be led to.

When the valve is closed during engine operation, the solenoid 131
Energization to the needle valve 140 is stopped and the spring 14
5 is pushed to the nozzle body 110 side, and the valve chamber 1
11 on the tapered surface 112 of the needle valve 140
One edge 148 abuts. Also a fuel pump (not shown)
The fuel pumped from the first space 1 of the intermediate portion 120
21 is sent to a portion above the second guide 144 and the force due to the pressure is added to the urging force of the spring 145. As a result, the fuel does not reach the injection hole and is not injected. When the engine is stopped, the fuel pump is also stopped, so the spring 145
Edge 1 of the valve body 141 of the needle valve 140 only by the urging force of
48 is pressed against the tapered surface 112 of the valve chamber 111 to prevent fuel leakage.

Next, FIG. 3 and FIG. 4 in which the tip portion thereof is enlarged when the low-pressure fuel is introduced during engine operation.
Will be described with reference to. First, because the engine is operating, the solenoid 131 of the drive unit 130 is energized to generate a magnetic force, and the relief valve 132 and the needle valve 140 are operated as described above.
Is attracted to the solenoid 131 side. Therefore,
The edge 148 of the needle valve 140 is separated from the taper surface 111 of the valve chamber 111 of the nozzle body 110, and the fuel pumped through the fuel pipe 123 receives the needle valve 140.
Fill around 141.

Here, the pressure of the fuel acts on the upper surface of the movable valve 152, so that the movable valve 152 is recessed at the tip of the valve chamber 110.
Although it tries to move toward the bottom of 50, the bias of the elastic body 151 cannot be overcome because the fuel pressure is low,
As a result, as shown in FIGS. 3 and 4, the movable valve 152 projects into the opening on the inlet side of the nozzle 113, and the opening area of the nozzle 113 on the inlet side is reduced. Therefore, at low pressure,
Since the fuel is injected from the injection hole having a small opening area, a small amount of fuel can be injected.

Next, the case where high-pressure fuel is introduced during engine operation will be described. In this case, the needle valve 14
Since the position of 0 is the same as the case of introducing low-pressure fuel, it will be described only with reference to FIG. 5 in which the tip is enlarged. When high-pressure fuel is introduced, the pressure of the fuel acts on the upper surface of the movable valve 152, and the elastic body 151 exerts a force to move the movable valve 152 toward the bottom of the recess 150 at the tip of the valve chamber 110.
And the movable valve 152 is pushed into the recess 150 of the valve chamber 111. As a result, as shown in FIG. 5, the movable valve 152 does not project into the opening on the inlet side of the nozzle 113, and the opening area on the inlet side of the nozzle 113 increases. Therefore, a large amount of fuel can be injected because the fuel is injected at high pressure from the injection hole having a large opening area.

A modification of the first embodiment will be described below. FIG. 6 shows a first modified example, and in this first modified example, a recess 150 at the tip of the valve chamber 110 is shown.
The difference is that a hole 150a is provided at the bottom of the. As a result, the fuel in the space below the movable valve 152 in the recess 150,
It is prevented that air or the like is accumulated and the movement of the movable valve 152 (to the bottom of the recess 150) is deteriorated and the opening area is reduced.

FIG. 7 shows a second modification,
The second modification is different in that the elastic body is an elastic body 151a made of an elastic resin such as rubber. As a result, the processing cost of the elastic body can be reduced as compared with the first embodiment.

FIG. 8 shows a third modification,
In the third modification, a space is formed below the movable valve 152, and the space is filled with fuel to utilize the compressibility of the fuel. As a result, cost is reduced because an elastic body is not particularly required.

FIG. 9 shows a fourth modification,
In the fourth modified example, the nozzles are arranged in two stages, that is, a first nozzle 113a and a second nozzle 113b each having a diameter smaller than that of the first embodiment. Then, when the valve is closed, as shown in FIG.
The first nozzle 11 in which the edge 148 of No. 1 is arranged on the upstream side
When the low pressure fuel is introduced by contacting the tapered surface 112 of the valve chamber 111 on the upstream side of 3a, only the first nozzle 113a arranged on the upstream side is opened to the downstream side as shown in FIG. 9B. Second nozzle 113b arranged
Is closed, and when high-pressure fuel is introduced, a first nozzle 113a arranged on the upstream side and a second nozzle 113b arranged on the downstream side as shown in FIG. 9C.
So that both of the first nozzle 113a and the second nozzle 113a are opened.
The nozzle 113b is arranged. By doing so, it is possible to clarify the difference between when the fuel is injected at a low pressure and when the fuel is injected at a high pressure.

Next, a second embodiment will be described. FIG. 10 shows a state in which the fuel injection device of the second embodiment is closed, and is substantially the same as the first embodiment except for the nozzle body 200. The valve body 200 has a nozzle body 210 and an intermediate portion 220. And a drive unit 230. Inside the nozzle body 210, the main valve chamber 21
1 is formed, and the valve body portion 241 of the main needle valve 240 and the first guide 242 move in the main valve chamber 211. A sub valve chamber 250 is formed in a valve body portion 241 of the main needle valve 240, and a sub needle valve 251 having a sub needle guide 252 is arranged in the sub valve chamber 250 while being biased by a sub spring 253. There is.

The first taper surface 212 of the main valve chamber 211 is made to coincide with the main needle taper surface 246 of the valve body 241 of the main needle valve 240, and the main spring 245 of the main spring 245 is closed when fuel is not injected. Due to the urging force, the main needle valve 240 is attached to the first tapered surface 212 of the main valve chamber 211.
The main needle taper surface 246 of the valve body portion 241 of the above is abutted as shown in FIG. 2, passed through the fuel passage 218, and introduced into the portion of the main valve chamber 211 above the first taper surface 212. Block fuel advance.

A plurality of first nozzles 214 are formed radially from a second taper surface 213 formed on the first taper surface 212 via a step, and the second taper surface 21 is further formed.
3 is a tapered tip columnar wall surface 2 that is connected to 3 through a corner 215.
A plurality of second nozzles 216 are radially formed from 16. A corner 215 between the second tapered surface 213 and the tip columnar wall surface 216 has a sub needle taper surface at the tip of the sub needle valve 251 when the valve is closed and when low pressure fuel is introduced as described later. 254 abuts.

A main needle valve 240 connected to the first guide 242 through a connecting rod 243 in the intermediate portion 220.
Space 22 for slidably receiving the second guide 244 of the
1 and a second space 222 that receives the main spring 245 that biases the entire main needle valve 240 toward the tip side. A communication hole 247 is formed in the center of the main needle valve 240 to connect the sub valve chamber 250 and a portion of the first space 221 above the second guide 244. The fuel passage 224 guides the fuel sent through the fuel pipe 223 to the fuel passage 218 of the nozzle body 210, and also to the portion of the first space 221 above the second guide 244 via the communication passage 225. The fuel passage 226 is a portion of the fuel passing through a return passage which will be described later,
2 and the nozzle body 210 to a portion above the main valve chamber 211.

A solenoid 231 is arranged in the drive unit 230. The solenoid 2 as in the first embodiment
When 31 is energized, a magnetic force is generated to draw the relief valve 232 toward the solenoid 231 side. As a result, communication passage 2
The outlet side of 34 is opened, and the upper portion of the first space 221 of the intermediate portion 220 above the second guide 244 is the return passage 233.
The fuel remaining in the relevant part is discharged when the valve is closed, and the main needle valve 240 is connected to the solenoid 2 as well.
Since the magnetic force generated by 31 acts, the solenoid 23
1, the outlet side of the communication passage 225 in the intermediate portion 220 is closed, and the fuel is guided to the main valve chamber 211 of the nozzle body 210.

When the valve is closed during engine operation, the solenoid 23
1 is stopped, the main needle valve 240 is pushed toward the nozzle body 210 by the main spring 245, and as described above, the main needle valve 240 is tapered to the first tapered surface 212 of the main needle valve 240. The surface 246 abuts. In addition, the fuel pumped from the fuel pump (not shown) is supplied to the second space of the first space 221 of the intermediate portion 220.
The force is sent to the portion above the guide 244 and the force due to the pressure is added to the urging force of the main spring 245. As a result, the fuel does not reach the injection hole and is not injected. When the engine is stopped, the fuel pump is also stopped. Therefore, the taper surface 2 of the valve body portion 241 of the main needle valve 240 is generated only by the urging force of the main spring 245.
46 is pressed against the first tapered surface 212 of the main valve chamber 211 to prevent fuel leakage.

Next, the case where low-pressure fuel is introduced during engine operation will be described with reference to FIG. First, since the engine is operating, the solenoid 231 of the drive unit 230 is energized to generate a magnetic force, and the relief valve 232 and the main needle valve 240 are attracted to the solenoid 231 side as described above. Therefore, the main needle taper surface 246 of the main needle valve 240 is connected to the main valve chamber 21 of the nozzle body 210.
1 is separated from the first tapered surface 213, and the fuel pipe 223
The fuel pumped through the space fills around the valve body 241 of the main needle valve 240.

Here, the fuel pressure acts on the lower surface of the auxiliary needle guide 252 of the auxiliary needle valve 251, and the auxiliary needle valve 2
The auxiliary needle taper surface 254 of 51 is to be separated from the first taper surface of the main valve chamber 211, but the biasing force of the auxiliary spring 253 cannot be overcome because the fuel pressure is low, and the auxiliary needle of the auxiliary needle valve 251 is not able to be overcome. Tapered surface 254
Is not separated from the first tapered surface of the main valve chamber 211,
The state is as shown in 1. As a result, the first nozzle 21
4 is open, but the inlet of the second nozzle 217 is closed, so that fuel is injected only from the first nozzle 214. Therefore, since the fuel is injected at a low pressure from the injection hole having a small opening area, a small amount of fuel can be injected.

Next, the case where high-pressure fuel is introduced during engine operation will be described with reference to FIG. In this case, the pressure of the fuel acts on the lower surface of the auxiliary needle guide 252 of the auxiliary needle valve 251, and the force for separating the auxiliary needle taper surface 254 of the auxiliary needle valve 251 from the first taper surface of the main valve chamber 211. However, since the fuel pressure is high, the urging force of the sub spring 253 is overcome and the sub needle valve 2
51 is pushed into the sub valve chamber 250 and the sub needle valve 2
The auxiliary needle taper surface 254 of 51 is separated from the first taper surface of the main valve chamber 211, and the state shown in FIG. 12 is obtained. At this time, the fuel or air above the sub needle guide 252 of the sub needle valve 251 is discharged through the communication hole 247 in the center of the main needle valve 240, so that the movement of the sub needle valve 251 is not hindered. As a result, not only the first nozzle 214 but also the inlet of the second nozzle 217 is opened, and the fuel is supplied to the first nozzle 214 and the second nozzle 217.
Is injected from both. Therefore, a large amount of fuel can be injected because the fuel is injected at high pressure from the injection hole having a large opening area.

Next, FIG. 13 shows a modification of the second embodiment. In this modified example, as in the first embodiment, the nozzle is a one-stage nozzle 214a having a large diameter. The nozzles 214a are formed radially from the second tapered surface 213 of the main valve chamber 211. The tapered surface of the tip of the sub needle valve 251 is the main valve chamber 211.
Secondary needle taper surface 254 that fits the second taper surface 213 of
It is a. When the auxiliary needle taper surface 254a is pressed against the second taper surface 213 of the main valve chamber 211, such as when the valve is closed and when low-pressure fuel is introduced, the edge 255 at which the auxiliary needle taper surface 254a starts,
The opening on the inlet side of the nozzle 214a is narrowed down toward the central portion of the nozzle 214a so that the opening area is reduced. 13A shows a state when the valve is closed, and FIG. 13B shows a state when low-pressure fuel is introduced. When the high-pressure fuel is introduced, as shown in FIG. 13C, the auxiliary needle taper surface 254a becomes the second taper surface 2 of the main valve chamber 211.
12, the opening on the inlet side is fully opened and the opening area is increased. By doing so, the number of man-hours for processing the nozzle can be reduced as compared with the second embodiment.

[0035]

According to the invention of each claim, the area of the injection hole is automatically changed according to the pressure of the fuel by the fuel pressure responsive injection hole area adjusting member in which the valve element is simply arranged on the elastic body. Therefore, it is possible to reliably change the injection hole flow rate according to the fuel pressure with an extremely simple configuration.

[Brief description of drawings]

FIG. 1 is a diagram showing a structure and an operation (when a valve is closed) of a first embodiment of the present invention.

FIG. 2 is an enlarged view of a nozzle body portion of FIG.

FIG. 3 is a diagram showing the structure and operation (at the time of introduction of low-pressure fuel) of the first embodiment of the present invention.

FIG. 4 is an enlarged view of a nozzle body portion of FIG.

FIG. 5 is an enlarged view of the nozzle body portion showing the structure and operation (during high-pressure fuel introduction) of the first embodiment of the present invention.

FIG. 6 is an enlarged view of a nozzle body portion of a first modification example of the first embodiment.

FIG. 7 is an enlarged view of a nozzle body portion of a second modified example of the first embodiment.

FIG. 8 is an enlarged view of a nozzle body portion of a third modification example of the first embodiment.

FIG. 9 is an enlarged view of a nozzle body portion of a fourth modified example of the first embodiment, in which (A) shows a state when the valve is closed,
(B) shows the state when the low-pressure fuel is introduced, and (C) shows the state when the high-pressure fuel is introduced.

FIG. 10 is a diagram showing the structure and operation (when the valve is closed) of the second embodiment of the present invention.

FIG. 11 is a diagram showing the structure and operation (during low-pressure fuel introduction) of the second embodiment of the present invention.

FIG. 12 is a diagram showing the structure and operation (during high-pressure fuel introduction) of the second embodiment of the present invention.

FIG. 13 is an enlarged view of a nozzle body portion of a modified example of the second embodiment, in which (A) shows the state when the valve is closed and (B) shows
Shows the state when the low-pressure fuel is introduced, and (C) shows the state when the high-pressure fuel is introduced.

[Explanation of symbols]

110 ... Nozzle body 111 ... Valve chamber 112 ... Tapered surface 113 ... Nozzle 114 ... Fuel passage 120 ... middle part 121 ... First space 122 ... Second space 123 ... Fuel pipe 124 ... Fuel passage 125 ... communication passage 126 ... Fuel passage 130 ... Drive unit 131 ... Solenoid 132 ... Relief valve 133 ... Return passage 134 ... Communication passage 140 ... Needle valve 141 ... Valve body 142 ... First Guide 143 ... connecting rod 144 ... Second Guide 145 ... Spring 146 ... First needle taper surface 147 ... First needle taper surface communication hole 148 ... Edge 150 ... Recess 151 ... Sub valve chamber 152 ... Sub needle valve 210 ... Nozzle body 211 ... Main valve chamber 212 ... First tapered surface 213 ... Second tapered surface 214 ... First nozzle 215 ... Corner 216 ... Tip-shaped wall surface 217 ... Second nozzle 218 ... Fuel passage 220 ... middle part 221 ... First space 222 ... Second space 223 ... Fuel pipe 224 ... Fuel passage 225 ... communication passage 226 ... Fuel passage 230 ... Drive unit 231 ... Solenoid 232 ... Relief valve 233 ... Return passage 234 ... Communication passage 240 ... Main needle valve 241 ... Valve body 242 ... First Guide 243 ... connecting rod 244 ... Second guide 245 ... Main spring 246 ... Main needle taper surface 247 ... Communication hole 250 ... Sub valve chamber 251 ... Secondary needle valve 252 ... Secondary needle guide 253 ... Secondary spring 254 ... Secondary needle taper surface

Continuation of the front page (56) Reference JP-A-11-62785 (JP, A) JP-A-11-30167 (JP, A) Actually open 4-17167 (JP, U) Actually open 62-43176 (JP , U) (58) Fields investigated (Int.Cl. ⁷ , DB name) F02M 61/18 330 F02M 61/18 320 F02M 61/18 350 F02M 61/10

Claims (3)

(57) [Claims] 1. A needle valve is movably disposed in a nozzle body at the tip of a valve body, and a needle valve seat portion is separated from the nozzle body seat portion and is formed on a downstream side of the nozzle body seat portion of the nozzle body. A fuel injection device for injecting fuel by injecting fuel into a hole, in which the opening area of the inlet of the injection hole is large when the pressure of the introduced fuel is high, and the opening area of the inlet of the injection hole is large when the pressure of the introduced fuel is low. The fuel pressure responsive injection hole area adjusting member is provided for changing the opening area of the inlet of the injection hole according to the fuel pressure so that the opening area becomes small, and the fuel pressure responsive injection hole area adjusting member is arranged in the nozzle body, The fuel pressure responsive injection hole area adjusting member is composed of an elastic member which is arranged at the inner tip of the nozzle body and expands and contracts according to the fuel pressure, and a valve body which is arranged on the elastic member. When it is introduced to the upper surface of the nozzle, the valve body moves along the inner surface of the tip of the nozzle body where the inlet of the injection hole is formed according to the fuel pressure to change the opening area of the inlet of the injection hole. Characteristic fuel injection device. 2. The fuel injection device according to claim 1, wherein the elastic member is made of an elastic resin. 3. The fuel injection device according to claim 1, wherein the elastic member is fuel filled between the valve body and the innermost tip portion of the nozzle body.