JP4078779B2 - Fuel injection valve - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fuel injection valve capable of injecting fuel in stages.
[0002]
[Prior art]
Conventionally, in order to achieve both low emissions (NOX, HC, black smoke), high output, and low fuel consumption in a diesel engine, it is necessary to make the injection rate variable according to the operating conditions of the engine. In order to realize this requirement, a two-stage valve opening pressure nozzle having two springs configured to urge the needle is known as a conventional technique.
[0003]
However, in this technique, the fuel pressure pumped from the fuel injection pump varies depending on the engine operating condition, so that it is difficult to realize the injection rate required by the engine under all operating conditions.
[0004]
Therefore, for example, a conventional fuel injection valve disclosed in US Pat. No. 5,694,903 includes a control chamber for applying fuel pressure to the needle in the direction of closing the nozzle hole. This controls injection by the magnitude relationship between the force received in the opening direction by the fuel pressure introduced into the nozzle fuel reservoir and the force received in the injection hole closing direction from the fuel pressure in the control chamber. By changing the opening area of the pilot valve stem that controls the fuel pressure in the control chamber, the control chamber pressure is changed, and the needle is lifted stepwise to obtain the required injection rate.
[0005]
Further, as disclosed in, for example, Japanese Patent Application Laid-Open No. 10-54323, fuel injection in which a control valve is disposed at each of an inlet portion and an outlet portion of high-pressure fuel to the control chamber to control the needle lift stepwise. There is a valve. According to this configuration, since the opening / closing control of the entrance and exit to the control room can be controlled independently, stable lift control and the amount of leakage can be reduced.
[0006]
[Problems to be solved by the invention]
However, in the conventional fuel injection valve configuration disclosed in US Pat. No. 5,694,903, the fuel pressure in the control chamber changes depending on the opening area of the stem, the fuel properties, the fuel temperature, etc. It became stable and stable injection rate control was difficult. In addition, a two-way valve is used as the control valve for controlling the control chamber pressure, and the high pressure fuel is constantly leaked through the control chamber and the discharge passage during the injection period. Increased, causing fuel consumption deterioration.
[0007]
In Japanese Patent Laid-Open No. 10-54323, since a plurality of solenoid valves are required, the fuel injection valve becomes large and expensive.
[0008]
In view of the above points, an object of the present invention is a fuel injection capable of controlling the needle lift in a stepwise manner so as to stably obtain the required injection rate in accordance with the entire operating state of the engine with a relatively small structure. To provide a valve.
[0009]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the fuel injection valve according to claim 1 and claim 2 of the present invention is stepwise by a drive device that electrically drives one valve body in the valve chamber constituting the control valve. By lifting the first opening, the first opening communicating with the first pressure chamber, the second opening communicating with the second pressure chamber, the low pressure opening communicating with the low pressure passage, the first opening or The low pressure opening was opened and closed to change the fuel pressure in the first pressure chamber and / or the second pressure chamber.
[0010]
The fuel injection valve lifts the first piston and the second piston stepwise by changing the pressures of the first pressure chamber and the second pressure chamber by stepwise lifting operation of one valve body. Since the first piston and the second piston cooperate with the valve member, the lift of the valve member can be controlled stepwise.
[0011]
As described above, the control valve having a simple configuration including a single valve body enables the fuel injection valve to be reduced in size, and the injection rate can be varied by lifting the first piston and the second piston in stages. A fuel injection valve.
[0012]
The fuel injection valve according to claim 3 of the present invention controls the fuel pressure in the first pressure chamber and the second pressure chamber by changing the fuel pressure in the first pressure chamber and the second pressure chamber in the following three steps. ing.
[0013]
First, before lifting the valve body in the valve chamber, the valve body closes the low-pressure opening. The high pressure fuel in the high pressure passage is guided to the valve chamber through the second opening of the valve chamber, and then the high pressure fuel is communicated to the first pressure chamber through the first opening. On the other hand, although the high pressure circuit communicated with the second pressure chamber communicates with the valve chamber, the low pressure opening is closed by the valve body. Therefore, the first piston and the second piston are urged in the valve closing direction by the high pressure fuel in the first pressure chamber and the second pressure chamber. The valve member is seated on the valve seat together with the biasing means for biasing the valve member in the nozzle hole closing direction in accordance with the lift amount of the valve member.
[0014]
Next, when the valve body performs the first lift, the valve body opens the low pressure opening, and the high pressure fuel in the first pressure chamber and the second pressure chamber communicates with the low pressure passage through the low pressure opening of the valve chamber. Therefore, the fuel pressure in the first pressure chamber and the second pressure chamber changes from the high pressure state to the low pressure state, and the first piston and the second piston lift in the valve opening direction as follows.
[0015]
When the first piston is lifted, it comes into contact with the second piston, and the second piston is lifted so that both the first piston and the second piston are lifted, so that the lift amount of the first piston and the lift amount of the second piston are The valve member is lifted by the combined amount, the valve member is separated from the valve seat, and fuel is injected from the injection hole.
[0016]
Next, when the valve body is lifted more than the first lift and then the second lift is performed, the first pressure chamber remains in communication with the low pressure passage through the valve chamber, so that the fuel pressure in the first pressure chamber is changed from the high pressure state to the low pressure state. The valve body closes the second opening, and the second pressure chamber blocks communication with the low-pressure passage. Therefore, the fuel pressure in the second pressure chamber is maintained at a high pressure, and the second piston is urged in the valve closing direction. That is, the first piston lifts and contacts the second piston, the valve member lifts by the lift amount of the first piston, the valve member moves away from the valve seat, and fuel is injected from the injection hole.
[0017]
In this way, a simple control valve composed of a single valve body provides an inexpensive fuel injection valve, and the first and second pistons are lifted stepwise to vary the injection rate. It can be a valve.
[0018]
Further, when the valve body performs the second lift and the valve member lifts by the lift amount of the first piston, the high pressure circuit and the low pressure circuit are shut off by closing the second opening. The wasteful work of the fuel pump that pumps the fuel is suppressed, and the fuel consumption is improved.
[0019]
According to a fourth aspect of the present invention, the urging means includes first urging means for urging the valve member in the nozzle hole closing direction regardless of the lift amount of the valve member. The first urging means is configured such that when the first pressure chamber and the second pressure chamber are connected to the low pressure passage and the urging force of the first piston and the second piston in the valve member closing direction is reduced, the valve member The urging force in the valve closing direction is maintained to prevent the valve member from separating from the valve seat.
[0020]
On the other hand, when the valve member is lifted more than the first lift, the second piston is provided so as to bias the valve member in the nozzle hole closing direction. The second piston is biased in the injection hole closing direction so that the inertial force due to the lift of the piston does not push up the second piston. Therefore, it can be set as the fuel injection valve from which the stable injection amount is obtained.
[0021]
In the fuel injection valve according to claim 5 of the present invention, the valve body lifts toward the drive device side and closes the low pressure opening, so that the valve body support portion where the valve body lifts and slides by the drive device is in a low pressure fuel atmosphere. It is in. Therefore, the amount of fuel leakage from the gap required for sliding the valve body support portion can be reduced.
[0022]
According to a sixth aspect of the present invention, in the fuel injection valve according to the sixth aspect of the present invention, the passage that connects the high pressure passage and the second pressure chamber is a first passage in which the high pressure passage is disposed in a passage that connects the second opening and the second pressure chamber. It is configured to be connected to the throttle portion at a position on the valve chamber side.
[0023]
When the first pressure chamber changes the fuel pressure from low pressure to high pressure, the high pressure fuel is supplied through the high pressure passage and the valve chamber, but compared with the case where the first pressure chamber is supplied from the high pressure passage through the second pressure chamber. Thus, there is an effect that one throttle portion between the high pressure passage and the second pressure chamber can be reduced.
[0024]
If the throttle part can be reduced by one, the fuel is smoothly supplied to the first pressure chamber, so that the pressure increase in the first pressure chamber is accelerated. For this reason, the force acting on the nozzle hole in the closing direction increases quickly, and the descending speed of the valve member can be increased. That is, the valve closing response of the valve member is improved.
[0025]
According to a seventh aspect of the present invention, there is provided a fuel injection valve having a passage connected between the high pressure passage and the first pressure chamber via a second throttle portion for adjusting the fuel flow.
[0026]
With this configuration, the high-pressure fuel can be introduced into the fuel passage from the high-pressure passage to the first pressure chamber not only through the valve chamber but also from the passage connecting the high-pressure passage and the first pressure chamber.
[0027]
With the configuration described above, the amount of fuel flowing into the first pressure chamber when the valve member is closed can be increased, and the pressure increase in the first pressure chamber can be accelerated. For this reason, the force acting on the nozzle hole in the closing direction increases quickly, and the descending speed of the valve member can be increased. That is, the valve closing response of the valve member is improved.
[0028]
The fuel injection valve according to claim 8 of the present invention is configured to be connected between the first pressure chamber and the second pressure chamber via a fourth throttle portion that adjusts the fuel flow.
[0029]
With this configuration, the high-pressure fuel can be introduced into the fuel passage from the high-pressure passage to the first pressure chamber not only via the valve chamber but also from the passage connecting the first pressure chamber and the second pressure chamber described above.
[0030]
With the configuration described above, the amount of fuel flowing into the first pressure chamber when the valve member is closed can be increased, and the pressure increase in the first pressure chamber can be accelerated. For this reason, the force acting on the nozzle hole in the closing direction increases quickly, and the descending speed of the valve member can be increased. That is, the valve closing response of the valve member is improved.
[0031]
The fuel injection valve according to claim 9 of the present invention comprises: Valve chamber And second 1 In the passage communicating with the pressure chamber, a wide tapered port portion is formed on the valve chamber side.
[0032]
The wide taper port on the valve chamber side facilitates the introduction of a high-pressure fuel flow when high-pressure fuel is introduced into the first pressure chamber via the valve chamber, and has the effect of increasing the pressure of the first pressure chamber quickly. is there. For this reason, the force acting on the nozzle hole in the closing direction increases quickly, and the descending speed of the valve member can be increased. That is, the valve closing response of the valve member is improved.
[0033]
In the fuel injection valve according to the tenth aspect of the present invention, the first throttle portion is eliminated, and the third throttle portion is disposed in the low-pressure passage so that the third throttle portion replaces the first throttle portion. Thus, the fuel flow between the high pressure passage and the first pressure chamber is adjusted.
[0034]
When the fuel pressure is changed from the high pressure to the low pressure in the second pressure chamber, even if the third throttling portion is rearranged in the low pressure passage instead of the first throttling portion, the third throttling portion is the first throttling portion. Similarly, the fuel pressure is in the path from the second pressure chamber to the low pressure passage, and the fuel pressure transition speed changing from high pressure to low pressure in the second pressure chamber is adjusted.
[0035]
On the other hand, since the first throttle portion is eliminated in the fuel passage from the high pressure passage to the first pressure chamber, the amount of fuel flowing into the first pressure chamber can be increased when the valve member is closed, and the pressure in the first pressure chamber is increased. As a result, the lowering speed of the valve member can be improved. That is, the valve closing response of the valve member is improved.
[0036]
According to an eleventh aspect of the present invention, the fuel injection valve communicates with the first pressure chamber by lifting one valve body in the valve chamber constituting the control valve stepwise by a drive device that electrically drives the control valve. The fuel pressure in the first pressure chamber and the second pressure chamber is changed by changing the first opening, the second opening communicating with the second pressure chamber, and the low pressure opening communicating with the low pressure passage through the following three steps. Is controlling.
[0037]
First, before lifting the valve body in the valve chamber, the valve body closes the low-pressure opening. The high-pressure fuel in the high-pressure passage is guided into the valve chamber through the second opening of the valve chamber, and then the high-pressure fuel is communicated with the first pressure chamber through the first opening. On the other hand, although the high pressure circuit communicated with the second pressure chamber communicates with the valve chamber, the low pressure opening is closed by the valve body. Therefore, the first piston and the second piston are urged in the valve closing direction by the high pressure fuel in the first pressure chamber and the second pressure chamber. The valve member is seated on the valve seat together with the biasing means for biasing the valve member in the nozzle hole closing direction in accordance with the lift amount of the valve member.
[0038]
Next, when the valve body performs the first lift, the valve body opens the low pressure opening, and the high pressure fuel in the first pressure chamber and the second pressure chamber communicates with the low pressure passage through the low pressure opening of the valve chamber. Therefore, the fuel pressure in the first pressure chamber and the second pressure chamber changes from the high pressure state to the low pressure state, and the first piston and the second piston lift in the valve opening direction as follows.
[0039]
When the second piston is lifted and locked to the locking member, the lift is restricted. When the first piston is lifted, the lift is restricted by contacting the second piston. The valve member is lifted by the sum of the lift amount of the first piston and the lift amount of the second piston, the valve member is separated from the valve seat, and fuel is injected from the injection hole.
[0040]
Next, when the valve body lifts more than the first lift and performs the second lift, since the second pressure chamber remains in communication with the low pressure passage through the valve chamber, the fuel pressure in the second pressure chamber is changed from the high pressure state to the low pressure state. The valve body closes the first opening and the first pressure chamber blocks communication with the low-pressure passage. Here, the first pressure chamber maintains a high pressure state, but the volume changes as the second piston rises, and the fuel pressure in the first pressure chamber decreases. However, the first piston moves by the amount of movement of the second piston by adjusting the supply of high-pressure fuel so that the pressure in the first pressure chamber is maintained at a high level. That is, the second piston is driven to the first piston by the lift amount of the first piston, the valve member is lifted, the valve member is separated from the valve seat, and the fuel is injected from the injection hole.
[0041]
With the above configuration, the valve member lift adjustment (the lift amount of the second piston) is facilitated.
[0042]
The fuel injection valve according to claim 12 of the present invention is such that the electrically driven drive device lifts the valve body by an electromagnetic coil. By using an electromagnetic coil, the electromagnetic coil can be mounted in a limited space, and the physique of the drive device can be made compact.
[0043]
A fuel injection valve according to a thirteenth aspect of the present invention is the fuel injection valve according to any one of the first to tenth aspects, wherein the electrically driven drive device lifts the valve body by a piezo actuator. It was set as the structure to do. The piezo actuator can be a fuel injection valve that has a quick displacement response to the application of electric charge and an excellent lift response of the valve member.
[0044]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a plurality of examples showing embodiments of the present invention will be described in detail with reference to the drawings.
[0045]
(First embodiment)
The configuration of the fuel injection valve according to the first embodiment of the present invention will be described with reference to FIGS. 1, 2, and 3. FIG. FIG. 1 is an overall sectional view of a fuel injection valve according to a first embodiment of the present invention. FIG. 2 is a partial cross-sectional view showing a state where the valve body of the fuel injection valve shown in FIG. 1 is lifted second. FIG. 3 is a partial cross-sectional view showing a state where the valve body of the fuel injection valve shown in FIG. 1 is first lifted.
[0046]
As shown in FIG. 1, the structure of the fuel injection valve 1 is basically that a first piston 21 and a second piston 22 are arranged above the first piston 21 in the fuel injection valve housing 10, and further the first piston. A first pressure chamber 50 is formed between the first piston 21 and the second piston 22, and a second pressure chamber 51 is formed on the upper surface of the second piston 22. The fuel pressure in the first pressure chamber 50 and the second pressure chamber 51 is controlled by the electromagnetic valve 30 disposed above the second pressure chamber 51, so that it is provided below the first piston 21 and will be described later. By changing the lift amount of the needle 23 that opens and closes the injection hole 11, the injection rate shape can be freely set.
[0047]
A housing 10 of the fuel injection valve 1 and a valve body 13 provided below the housing 10 are fastened by a retaining nut 12 with a tip packing 14 interposed therebetween. The control device 20 includes a first piston 21, a first pressure chamber 50, a second piston 22, and a second pressure chamber 51 from the injection hole 11 side formed at the lower end of the valve body 13, and the injection device side of the control device 20. Are arranged with a needle 23 and a rod 24 which cooperate with the control device 20. The needle 23 is supported by the valve body 13 so as to be reciprocally movable. Furthermore, a first needle spring 15 that urges the needle 23 in the direction of the nozzle hole 11 via the rod 24 is provided.
[0048]
Further, the housing 10 is formed with a high-pressure passage 60 communicating with a common rail (not shown). The high-pressure passage 60 passes through the housing 10, the tip packing 14, and the valve body 13 and communicates with the fuel reservoir 16 formed in the valve body 13. Further, the high pressure passage 60 is formed so as to communicate with the second pressure chamber 51 via a communication passage 68. As a result, the high-pressure fuel supplied from the common rail (not shown) is supplied to the second pressure chamber 51 and the fuel reservoir 16 in the valve body 13 via the high-pressure passage 60 in the housing 10. Further, as shown in FIG. 2, the first pressure chamber 50 is communicated with a communication passage 61 opened in the second pressure chamber 51 and a communication passage 64 formed in the housing 10 and the like via a valve chamber 62 described later. The fuel is supplied from the second pressure chamber 51.
[0049]
The control valve 30 is accommodated in the valve cover 38 and is screwed between the upper portion of the housing 10 and the valve cover 38. The control valve 30 includes a body 31, an armature 32, a stopper 33, a first spring 34, an electromagnetic coil 35, a second spring 36, a valve body 37, a plate 39, a valve chamber 62, and the like.
[0050]
The valve chamber 62 is formed in the body 31 and accommodates a valve body 37 connected to the armature 32. A second opening 65 connected to the communication passage 61 is opened at the upper end surface of the valve chamber 62 at the connection portion of the armature 32 with the valve body 37. Further, a first opening 66 connected to the communication passage 64 is opened on the side surface of the substantially central portion of the valve chamber 62. Furthermore, a low pressure opening 67 in which the plate 39 is formed opens at the lower end surface of the valve chamber 62.
[0051]
The low pressure opening 67 is connected to the low pressure passage 63. The low-pressure passage 63 is formed in the housing 10 and the like, and communicates with a fuel tank (not shown) so that the fuel in the valve chamber 62 is discharged to the fuel tank.
[0052]
The valve body 37 can be seated on the low-pressure opening 67 via the armature 32 by the urging force of the first spring 34. Further, the valve element 37 moves upward together with the armature 32 by the suction of the electromagnetic coil 35 and can be seated in the second opening 65.
[0053]
In FIG. 1, the valve element 37 is seated in the low pressure opening 67 without energizing the electromagnetic coil 35, the needle 23 is attached to the fuel pressure of the first pressure chamber 50, the second pressure chamber 51, and the first needle spring 15. A state in which the valve is biased in the valve closing direction by the force and is seated on the valve seat 13A is shown. In addition, 23a shows the shoulder part of the needle 23, 11a shows the lower end surface of the housing 11. FIG.
[0054]
Next, the armature 32 located above the valve body 37 is attracted upward against the biasing force of the first spring 34 by the excitation suction force generated by energizing the coil 35, and the valve body 37 is Lift. This state is shown in FIG.
[0055]
As shown in FIG. 3, the valve body is lifted upward and sucked to the lower end surface of the stopper 33. At this time, since the urging force of the second spring 36 is applied to the valve body 37, the sum of the attraction force from the electromagnetic coil 35 and the urging forces of the first spring 34 and the second spring 36 balances the valve body 37 with the lift H1. Stop at the position (see FIG. 1).
[0056]
When the current value supplied to the electromagnetic coil 35 is higher, the force for attracting the valve element 37 is further increased, and the valve element 37 is raised against the sum of the urging forces of the first spring 34 and the second spring 36. To do. Then, as shown in FIG. 2, the valve body 37 comes into contact with the second opening 65 formed inside the valve chamber 62, and the second lift until the second opening 65 is closed and stopped. do. As shown in FIG. 1, the lift amount from the position where the valve body 37 is seated on the low-pressure opening 67 to the second opening 65 is H2. The amount by which the valve body 37 moves from the first lift to the second lift is (H2-H1).
[0057]
Next, the operation of the fuel injection valve 1 will be described with reference to FIGS. 1 to 3 and FIG.
[0058]
A drive current to the electromagnetic coil 35 corresponding to engine operating conditions is generated by an engine control unit (ECU) (not shown) and supplied to the electromagnetic coil 35. When the drive current is supplied, the armature 32 is sucked and the valve element 37 is lifted.
[0059]
When the lift of the valve body 37 is H2 (see timing (A) in FIGS. 2 and 4), the passage between the second pressure chamber 51 and the valve chamber 62 while the valve chamber 62 and the low-pressure passage 63 remain in communication with each other. Is blocked by the second opening 65. That is, the second pressure chamber 51 to which high pressure fuel from a common rail (not shown) is supplied is not in communication with the low pressure passage 63. On the other hand, since the first pressure chamber 50 and the low pressure passage 63 communicate with each other through the first opening 66 of the valve chamber 62, the fuel pressure (PC1) in the first pressure chamber 50 decreases, and the first needle spring 15 When the force in the nozzle hole closing direction, which is the resultant force of the set load and the force received from the fuel pressure in the first pressure chamber 50, becomes smaller than the force pushing up the needle 23 due to the fuel pressure in the fuel reservoir, the needle 23 begins to open. The fuel pressure in the first pressure chamber 50 decreases and the needle 23 rises. However, when the needle 23 rises (h1 lift), the first piston 21 comes into contact with the lower surface of the second piston 22. At this time, the fuel pressure (PC2) in the second pressure chamber 51 is kept high, and the force received from the fuel pressure in the second pressure chamber 51 is larger than the force that works in the nozzle hole closing direction and pushes up the needle 23. The needle 23 does not lift (h1 lift) or more.
[0060]
When the lift of the valve element 37 is H1 (see timing (B) in FIGS. 3 and 4), all of the first opening 66, the second opening 65, and the low pressure opening 67 are opened. Thus, since the first pressure chamber 50 and the second pressure chamber 51 communicate with the low pressure passage 63, the fuel pressure in the first pressure chamber 50 and the second pressure chamber 51 decreases. Therefore, the force acting in the nozzle hole closing direction is smaller than the force pushing up the needle 23, and the needle 23 is lifted (h1 lift) or more and raised to (h2 lift). At this time, the shoulder 23a of the needle 23 is locked to the lower end surface 11a of the housing 11, and the needle 23 does not lift any more.
[0061]
It is also possible to change the lift of the needle 23 stepwise from h1 to h2 by changing the lift amount of the valve element 37 from H2 to H1 during the injection period as shown in the timing (C) in FIG. is there.
[0062]
When the supply of drive current to the electromagnetic coil 35 is stopped after a predetermined time and the valve element 37 closes the low pressure opening 67, the low pressure passage 63 and the valve chamber 62 are shut off, so the first pressure chamber 50 and the first pressure chamber 50 The fuel pressure in the two pressure chambers 51 rises, and the force that pushes down the first piston 21 and the second piston 22 in the needle 23 closing direction rises, closing the needle 23.
[0063]
As described above, since the control valve having a simple configuration including one valve body is used, the structure of the fuel injection valve itself can be reduced in size, and the fuel injection valve can be made cheaper than the conventional one, and the first piston and the second piston. Can be lifted stepwise to provide a fuel injection valve with variable injection rate.
[0064]
Further, when the valve body 37 performs the second lift and only the first piston 21 lifts, that is, when the needle 23 that is the valve member is h1, high-pressure fuel such as the high-pressure circuit 60 is released to the low-pressure passage 63 side. The h1 lift of the needle 23 can be achieved. For this reason, useless work of the fuel pump that pumps high-pressure fuel when the needle 23 is lifted by h1 is suppressed, and there is an effect of improving fuel consumption.
[0065]
(Modification)
In the first embodiment, the first needle spring 15 is provided as a means for urging the needle 23 in the closing direction of the nozzle hole 11. In this modification, as shown in FIG. 5, the second needle spring 17 is provided inside the second pressure chamber 51 in addition to the first needle spring 15 (FIG. 1).
[0066]
In the second needle spring 17, the fuel pressure in the first pressure chamber 50 decreases, the first piston 21 lifts and comes into contact with the second piston 22, and the inertia force generated by the lift of the first piston 21 pushes up the second piston 22. In order to prevent this, in addition to the fuel pressure in the second pressure chamber 51, the second piston 22 is urged in the injection hole closing direction, so that only (h1 lift) is lifted reliably. Therefore, it can be set as the fuel injection valve from which the stable injection amount is obtained.
[0067]
(Second embodiment)
A second embodiment of the present invention is shown in FIG. Components that are substantially the same as those of the first embodiment are denoted by the same reference numerals, and description thereof is omitted. The difference from the first embodiment is that the electromagnetic coil 35 is disposed below the armature 32. With this configuration, the attractive force acting on the armature 32 due to the energization of the electromagnetic coil 35 acts in the downward direction, and the valve element 37 is lifted downward. When the supply of the drive current to the electromagnetic coil 35 is stopped, the low pressure opening 67 is closed to increase the fuel pressure in the first pressure chamber 50 and the second pressure chamber 51, and the needle 23 is not closed. Since the injection state is desired, the low pressure opening 67 can be disposed at the upper portion, and the arrangement of the high pressure passage 62 and the low pressure passage 64 can be changed. With the above-described configuration, the amount of fuel leakage from the gap 31a between the valve body 37 and the body 31 can be reduced.
[0068]
(Third embodiment)
A third embodiment of the present invention is shown in FIG. Components that are substantially the same as those of the first embodiment are denoted by the same reference numerals, and description thereof is omitted. The difference from the first embodiment is that a piezoelectric element is used in place of the electromagnetic coil 35 as the driving force of the valve element 37. The piezoelectric element 101 is inserted into the housing 11 and supplied with electric charges from a driving power source according to an instruction of a control computer (not shown), whereby the piezoelectric element 101 changes its length in the axial direction of the needle 23.
[0069]
Since the position of the upper end portion of the piezoelectric element 101 is regulated by the housing 11, the force is transmitted in the direction of the first hydraulic piston 102 by changing the overall length. The first hydraulic piston 102 is biased upward by a spring 104 and is set to follow the movement of the piezoelectric element 101. The first hydraulic piston 102 pushes the second hydraulic piston 105 having the cross-sectional area AH2 through the fuel in the lower hydraulic chamber 103 with the cross-sectional area AH1 (of the first hydraulic piston 102), whereby the second hydraulic piston 105 Is driven by the piezoelectric element 101 with a lift amount that is the reciprocal of the area ratio (AH1 / AH2).
[0070]
The hydraulic chamber 103 is formed by a housing 11 and hydraulic pistons 102 and 105. The second hydraulic piston 105 is regulated to move upward by a stopper 108 and is urged upward by a spring 106. The spring 106 is formed in the inner diameter portion 107 of the housing 11, and the inner diameter portion 107 communicates with a fuel tank (not shown) via the low pressure passage 63.
[0071]
The second hydraulic piston 105 is configured such that the small diameter portion 109 abuts on the valve body 37 at an appropriate minute distance. The inner diameter portion 107 communicates with the first pressure chamber 50 via the communication passage 64 and the second pressure chamber via the communication passage 61 when the valve element 37 opens downward to open the low pressure opening 67. 51 communicates. The second pressure chamber 51 communicates with a high-pressure passage 60 that communicates with a common rail (not shown).
[0072]
According to this configuration, it is possible to perform the same operation as in the first embodiment by changing the charge applied to the piezoelectric element 101 and controlling the lift amount of the valve element 37.
[0073]
When the needle 23 is lifted to (h1 lift), the piezoelectric element 101 is driven so as to give a large displacement. As the piezoelectric element 101 extends, the first hydraulic piston 102 is driven against the spring 104. According to the displacement of the piston 102, the fuel in the hydraulic chamber 103 is pressurized to increase the fuel pressure. The high pressure fuel drives the second hydraulic piston 105 downward against the spring 106. The small diameter portion 109 of the second hydraulic piston 105 abuts on the valve element 37, and the valve element 37 moves downward and abuts on the plate 39. At this time, the inner diameter portion 107 and the communication passage 61 are blocked by the valve body 37. When the valve body 37 moves downward, the first pressure chamber 50 communicates with the low-pressure passage 63 via the communication passage 64 and the inner diameter portion 107, so the first pressure chamber pressure decreases, and the force acting on the nozzle hole in the closing direction is small. Therefore, the needle 23 is opened. The first piston 21 comes into contact with the second piston 22 as the needle 23 is raised, but the lift of the needle 23 stops because the fuel pressure in the second pressure chamber 51 is high.
[0074]
When the piezoelectric element 101 is driven so as to give a small displacement, the small diameter portion 109 of the second hydraulic piston 105 contacts the valve element 37 and adjusts the displacement amount of the piezoelectric element 101 to a position where it does not contact the plate 34. Since the first pressure chamber 50 and the second pressure chamber 51 communicate with the low pressure passage 63 via the communication passages 64 and 62 and the inner diameter portion 107, the fuel pressure in the first pressure chamber 50 and the second pressure chamber 51 decreases. . Thereby, even after the first piston 21 abuts on the second piston 22, the force acting in the nozzle hole closing direction becomes smaller than the pushing force of the needle 23, so that the needle 23 abuts on the tip packing 14 (lift Amount: H2) Lift.
[0075]
Moreover, it is also possible to obtain an injection rate such as the boot injection rate by switching the displacement amount of the piezoelectric element 101 during the injection.
[0076]
The control valve by the piezoelectric element 101 having the above-described configuration can be a fuel injection valve that has a quick displacement response to applying an electric charge and an excellent lift response of the needle 23.
[0077]
(Fourth embodiment)
A fourth embodiment of the present invention is shown in FIG. Components that are substantially the same as those of the first embodiment are denoted by the same reference numerals, and description thereof is omitted. This embodiment differs from the first embodiment in that high-pressure fuel is communicated with the first pressure chamber 50 and the amount of movement of the needle 23 (h1 lift) is defined on the second piston 22 side.
[0078]
The operation of the fourth embodiment will be described below.
[0079]
When the lift of the valve body 37 is H2, the valve body 37 closes the second opening 65, and the pressure in the first pressure chamber 50 is blocked from the low pressure passage 63. The fuel pressure in the first pressure chamber 50 is introduced into the first pressure chamber via the high pressure passage 60 and the communication passage 202 to maintain a high pressure state. On the other hand, the fuel pressure in the second pressure chamber 51 is communicated with the low pressure passage 63 through the communication passage 261, the first opening 66, and the low pressure opening 67 in this order, and becomes low pressure. Therefore, since the urging force of the second piston 22 toward the valve closing side becomes small, the second piston 22 rises and comes into contact with the locking member 201 provided on the second pressure chamber 51 (h1 lift) and stops.
[0080]
On the other hand, although the high pressure is maintained in the first pressure chamber 50, the volume of the first pressure chamber 50 changes as the second piston 22 rises, and the fuel pressure in the first pressure chamber 50 decreases. However, the first piston 21 maintains the gap h <b> 2 by adjusting the fuel supply amount from the communication passage 202 by the throttle 203 so that the pressure in the first pressure chamber 50 is maintained at a high pressure.
[0081]
When the lift of the valve body 37 is H1, since the pressures of the first pressure chamber 50 and the second pressure chamber 51 are both reduced, the lift of the needle 23 is further increased (h2 lift).
[0082]
By adopting such a configuration of the fourth embodiment, the adjustment of the first lift amount (h1 lift) is simplified.
[0083]
(5th Example)
A fifth embodiment of the present invention is shown in FIG. Components that are substantially the same as those of the first embodiment are denoted by the same reference numerals, and description thereof is omitted. The difference from the first embodiment is that the route through which the high pressure fuel is introduced from the high pressure passage 60 to the second pressure chamber 51 is changed.
[0084]
The path through which the high-pressure fuel is introduced from the high-pressure passage 60 to the second pressure chamber 51 in the first to third embodiments is via the communication passage 68. In the fifth embodiment, instead of the communication passage 68 of the first embodiment, a communication passage 368 for connecting the high pressure passage 60 to the communication passage 61 for connecting the valve chamber 62 and the second pressure chamber 51 is disposed. The communication passage 368 is connected to the communication passage 61 on the valve chamber side with respect to the throttle portion 301 provided in the communication passage 61.
[0085]
With the configuration described above, there is an effect that the throttle portion in the fuel passage communicating from the high pressure passage 60 to the first pressure chamber 50 can be reduced by one as compared with the first to third embodiments.
[0086]
If the throttle portion can be reduced by one, when the valve body 37 is closed and the low pressure opening 67 is closed (when the lift of the valve body 37 is 0), the fuel supply to the first pressure chamber 50 is smoothly performed. Therefore, the pressure increase in the first pressure chamber 50 is accelerated. For this reason, the force acting on the nozzle hole in the closing direction increases quickly, and the descending speed of the needle 23 can be increased. That is, the valve closing response of the needle 23 is improved.
[0087]
(Sixth embodiment)
A sixth embodiment of the present invention is shown in FIG. Components that are substantially the same as those of the first embodiment are denoted by the same reference numerals, and description thereof is omitted. In the sixth embodiment of the present invention, the needle 23 descending speed is improved by a method different from the method of improving the needle 23 descending speed shown in the fifth embodiment.
[0088]
The difference from the first embodiment is that a communication passage 401 through which high-pressure fuel is introduced from the high-pressure passage 60 to the second pressure chamber 51 is added.
[0089]
As shown in FIG. 10, the high-pressure passage 60 and the first pressure chamber 50 are communicated with each other via the throttle portion 402 through the communication passage 401. With this configuration, the fuel passage from the high pressure passage 60 to the first pressure chamber 50 can introduce high pressure fuel from the communication passage 401 in addition to the communication passage 64 via the valve chamber 62.
[0090]
With the configuration described above, the amount of fuel flowing into the first pressure chamber 50 when the needle 23 is closed can be increased, and the pressure increase in the first pressure chamber 50 can be accelerated. The area of the throttle portion 402 between the high pressure passage 60 and the first pressure chamber 50 needs to be set to such an extent that the amount of fuel leakage from the high pressure passage 60 toward the first pressure chamber 50 does not increase when the needle 23 is opened.
[0091]
(Modification)
In the sixth embodiment, the throttle portion 301 is disposed in the communication passage 61 that communicates between the valve chamber 62 and the second pressure chamber 51. In the present modification, a throttle portion 403 is provided in the low pressure passage 63 as shown in FIG.
[0092]
When the valve body 37 is lifted downward in FIG. 11, the high-pressure fuel in the second pressure chamber 51 is introduced through the communication passage 61, the valve chamber 62, and the low-pressure passage 63 in this order.
[0093]
Therefore, even if the throttle portion is changed to the position of the present modification, it is in the path from the second pressure chamber 51 to the low pressure passage 63, and adjusts the fuel pressure transition speed that changes from the high pressure to the low pressure in the second pressure chamber 51. ing.
[0094]
On the other hand, according to this modification, the communication portion 61 that is a fuel passage from the high pressure passage 60 to the first pressure chamber 50 does not have the throttle portion 301 shown in the sixth embodiment, and the first pressure chamber 50 when the needle 23 is closed. The amount of inflow fuel can be increased, and the pressure rise in the first pressure chamber 50 can be accelerated, so that the needle 23 descending speed is improved.
[0095]
(Seventh embodiment)
A seventh embodiment of the present invention is shown in FIG. Components that are substantially the same as those of the first embodiment are denoted by the same reference numerals, and description thereof is omitted. The seventh embodiment of the present invention improves the needle 23 lowering speed by a method different from the method of improving the needle 23 lowering speed shown in the fifth and sixth embodiments.
[0096]
The difference from the first embodiment is that a communication passage 501 through which high-pressure fuel is introduced from the high-pressure passage 60 to the second pressure chamber 51 is added.
[0097]
As shown in FIG. 12, the second pressure chamber 51 and the first pressure chamber 50 are communicated with each other by providing a communication passage 501 in the second piston through the throttle portion 502. With this configuration, the fuel passage from the high pressure passage 60 to the first pressure chamber 50 has a high pressure from the communication passage 501 via the communication passage 68 and the first pressure chamber 50 in addition to the communication passage 64 via the valve chamber 62. Fuel can be introduced.
[0098]
With the configuration described above, the amount of fuel flowing into the first pressure chamber 50 when the needle 23 is closed can be increased, and the pressure increase in the first pressure chamber 50 can be accelerated. The area of the throttle portion 502 between the high pressure passage 60 and the first pressure chamber 50 needs to be set to such an extent that the amount of fuel leakage from the second pressure chamber 51 toward the first pressure chamber 50 does not increase when the needle 23 is opened. .
[0099]
Further, by combining with the fifth and sixth embodiments described above, the lift lowering speed when the needle 23 is closed can be further improved, and the sharp cut performance of the fuel injection rate is improved.
[0100]
(Modification)
In the seventh embodiment, the throttle portion 503 is disposed in the communication passage 64 provided in the plate 39. The throttle unit 503 is a throttle unit that adjusts the fuel flow rate by, for example, providing a fine hole in the plate 39 and adjusting the diameter of the fine hole.
[0101]
In this modification, as shown in FIG. 13, a wide taper port portion 64a is formed on the valve chamber 62 side of the plate 39 constituting the communication passage 64 formed of the fine pores that achieve the throttling effect. The diameter on the wide side of the tapered port portion 64a is connected to the valve chamber 62 side without being reduced.
[0102]
In the fuel passage from the high-pressure passage 60 to the first pressure chamber 50, high-pressure fuel is introduced through the second pressure chamber 51 and the valve chamber 62 in this order, so that the introduction passage is long and the first pressure chamber 50 is increased in pressure. It takes time. By forming the wide tapered port portion 64a on the side where the high-pressure fuel is introduced, that is, on the valve chamber 62 side, the high-pressure fuel can be easily introduced, and the first pressure chamber 50 can be increased in pressure quickly.
[Brief description of the drawings]
FIG. 1 is a sectional view showing a fuel injection valve according to a first embodiment of the present invention.
(A) is a whole sectional view.
FIG. 1 (B) is a 90 ° rotation cross-sectional view of FIG. 1 (A).
FIG. 2 is a partial cross-sectional view showing a state where a valve body of the fuel injection valve shown in FIG. 1 is second lifted.
FIG. 3 is a partial cross-sectional view showing a state where the valve body of the fuel injection valve shown in FIG. 1 is first lifted.
FIG. 4 is a time chart for realizing the stage lift of the first embodiment.
FIG. 5 is a cross-sectional view showing a control valve according to a modification of the first embodiment of the present invention.
FIG. 6 is a partial cross-sectional view showing a second embodiment of the present invention in which the arrangement of electromagnetic coils is changed.
FIG. 7 is an overall sectional view showing a fuel injection valve according to a third embodiment of the present invention.
FIG. 8 is a partial sectional view showing a fuel injection valve according to a fourth embodiment of the present invention.
FIG. 9 is a partial sectional view showing a fuel injection valve according to a fifth embodiment of the present invention.
FIG. 10 is a partial sectional view showing a fuel injection valve according to a sixth embodiment of the present invention.
FIG. 11 is a partial sectional view showing a fuel injection valve according to a modification of the sixth embodiment of the present invention.
FIG. 12 is a partial sectional view showing a fuel injection valve according to a seventh embodiment of the present invention.
FIG. 13 is a partial sectional view showing a throttle portion of a fuel injection valve according to a modification of the seventh embodiment of the present invention.
[Explanation of symbols]
1 Fuel injection valve
11 hole
13 Valve body
13a Valve seat
15 First needle spring (biasing means)
17 Second needle spring (biasing means)
20 Control device (control means)
21 First piston
22 Second piston
23 Needle (Valve member)
24 Rod
30 Control valve
32 Armature
33 Stopper
34 First spring (first spring)
35 Electromagnetic coil
36 Second spring (second spring)
32, 33, 34, 35, 36 Driving device
37 Disc
50 First pressure chamber
51 Second pressure chamber
60 High pressure passage
62 Valve chamber
63 Low pressure passage
64a taper mouth
65 second opening
66 First opening
67 Low pressure opening
101 Piezoelectric element (piezo actuator)
201 Locking member
301 first aperture
402 Second aperture
403 Third aperture
502 Fourth aperture

Claims (13)

A valve member for opening and closing the nozzle hole;
A valve body having a valve seat on the fuel upstream side of the nozzle hole, wherein the valve member is seated on the valve seat to close the nozzle hole, and the valve member is separated from the valve seat. A valve body for opening and closing the nozzle hole;
Control means for controlling the injection rate of fuel to be injected by lifting the valve member stepwise;
A control valve for switching a communication state between the control means and a high-pressure passage into which high-pressure fuel is introduced, and a communication state between the control means and a low-pressure passage through which the high-pressure fuel is discharged;
Biasing means for biasing the valve member in the nozzle hole closing direction;
The control means includes a first piston and a second piston that cooperate in the axial direction with the valve member, and a first pressure that changes the fuel pressure to lift the first piston and the second piston in the valve opening direction, respectively. A chamber and a second pressure chamber,
The control valve includes a valve chamber including one valve body therein, and an electric drive device that lifts and drives the valve body in stages.
The valve chamber includes a first opening communicating with the first pressure chamber, a second opening communicating with the high pressure passage and the second pressure chamber, and a low pressure opening communicating with the low pressure passage. Provided,
The valve body is lifted stepwise to switch the communication state between the first opening, the second opening, and the low pressure opening, and the fuel pressure in the first pressure chamber and the second pressure chamber is changed. A fuel injection valve characterized by being changed. The first pressure chamber is provided between the first piston and the second piston, and changes the fuel pressure to lift the first piston in the valve opening direction, and the second pressure chamber is the second pressure chamber. An upper portion of the piston is provided to change the fuel pressure to lift the second piston in the valve opening direction, and the first piston and the second piston are brought into contact with the second piston when the first piston is lifted. In addition, the first piston and the second piston are both lifted by lifting the second piston, and
The fuel injection valve according to claim 1, wherein the high-pressure passage communicates with the second pressure chamber. Before the valve body is lifted by the drive device, the valve body closes the low-pressure opening,
When the valve body performs a first lift by the driving device, the valve body opens the low pressure opening, and the first pressure chamber and the second pressure chamber communicate with the low pressure passage through the valve chamber,
When the valve body is lifted more than the first lift by the driving device to make the second lift, the first pressure chamber remains in communication with the low pressure passage through the valve chamber, and the valve body opens to the second opening. 3. The fuel injection valve according to claim 1, wherein the second pressure chamber blocks communication and blocks communication with the low-pressure passage. 4. The biasing means includes a first biasing means for biasing the valve member in the nozzle hole closing direction regardless of a lift amount of the valve member, and a nozzle hole closing direction when the valve member is lifted more than the first lift. The fuel injection valve according to any one of claims 1 to 3, further comprising: a second urging unit that urges the valve member. The fuel injection valve according to any one of claims 1 to 4, wherein the valve body lifts toward the driving device and closes the low-pressure opening. A first throttle for adjusting fuel flow is disposed in a passage communicating the second opening and the second pressure chamber;
The passage that communicates the high pressure passage and the second pressure chamber is configured such that the high pressure passage is disposed in a passage that communicates the second opening and the second pressure chamber. The fuel injection valve according to any one of claims 1 to 5, wherein the fuel injection valve is configured by connecting at a position on a valve chamber side. 7. The fuel injection valve according to claim 1, wherein the fuel injection valve is connected between the high-pressure passage and the first pressure chamber via a second throttle portion that adjusts a fuel flow. 8. The fuel injection valve according to claim 1, wherein a connection is made between the first pressure chamber and the second pressure chamber via a fourth throttle portion that adjusts a fuel flow. 9. . The fuel injection valve according to any one of claims 1 to 8, wherein a wide tapered port portion is formed on the valve chamber side in a passage communicating the valve chamber and the first pressure chamber. 10. The fuel flow between the high pressure passage and the first pressure chamber is adjusted by disposing a third throttle portion in the low pressure passage. 10. The fuel injection valve according to any one of the above. A valve member for opening and closing the nozzle hole;
A valve body having a valve seat on the fuel upstream side of the nozzle hole, wherein the valve member is seated on the valve seat to close the nozzle hole, and the valve member is separated from the valve seat. A valve body for opening and closing the nozzle hole;
Control means for controlling the injection rate of fuel to be injected by lifting the valve member stepwise;
A control valve for switching a communication state between the control means and a high-pressure passage into which high-pressure fuel is introduced, and a communication state between the control means and a low-pressure passage through which the high-pressure fuel is discharged;
The control means includes a first piston and a second piston that cooperate in the axial direction with the valve member, and an urging means that urges the valve member in a nozzle hole closing direction in accordance with a lift amount of the valve member. ,
A first pressure chamber provided between the first piston and the second piston, wherein the fuel pressure is changed to lift the first piston in a valve opening direction; and an upper portion of the second piston. A second pressure chamber for changing and lifting the second piston in the valve opening direction;
A locking member provided at an upper portion of the second pressure chamber and restricting a lift of the valve member;
The first piston and the second piston are arranged to contact the locking member when the second piston is lifted, and to contact the second piston when the first piston is lifted,
The high pressure passage communicates with the second pressure chamber;
The control valve includes a valve chamber having a single valve body therein, and an electric drive device that lifts the valve body in stages.
The valve chamber includes a first opening communicating with the first pressure chamber, a second opening communicating with the second pressure chamber, and a low pressure opening communicating with the low pressure passage,
Before the valve body is lifted by the driving device, the valve body closes the low-pressure opening, and when the valve body performs the first lift by the driving device, the valve body opens the low-pressure opening. Then, the first pressure chamber and the second pressure chamber communicate with the low pressure passage through the valve chamber, and when the valve body lifts more than the first lift by the driving device and performs the second lift, The two pressure chambers remain in communication with the low pressure passage through the valve chamber, the valve body closes the first opening, and the first pressure chamber blocks communication with the low pressure passage. Fuel injection valve. The fuel injection valve according to any one of claims 1 to 11, wherein the electrically driven driving device lifts the valve body by an electromagnetic coil. The fuel injection valve according to any one of claims 1 to 12, wherein the electrically driven drive device lifts the valve body by a piezo actuator.

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