JPH0519561U - Fuel injector - Google Patents

Abstract

(57) [Abstract] [Purpose] To maintain fuel pressure when the engine is stopped and prevent initial fuel discharge when the engine is restarted in a pressure-balanced fuel injection device. [Structure] Fuel pressure regulators 2 and 33 of the same type having a negative pressure chamber for applying intake manifold pressure are arranged in parallel downstream of the fuel pump 1. The fuel pressure regulator 2 communicates with the fuel pressure regulator 14 that generates a regulated fuel pressure according to the required fuel flow rate via the fuel injection valve 20 and the fuel bypass 31 via the main fuel passage 32. The fuel pressure of the fuel pressure regulator 33 is adjusted to be lower than the fuel pressure of the fuel pressure regulator 2.
The purpose is achieved by adopting a normal / closed system for each fuel pressure regulator and additionally disposing a fuel pressure regulator 33.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a fuel injection device of a pressure balance type in which the fuel injection amount is controlled according to the intake manifold pressure and the engine speed, and in particular, the fuel pressure is maintained when the engine is stopped, and the initial stage when restarting The present invention relates to a pressure-balanced fuel injection device that prevents fuel discharge.

[0002]

[Prior Art]

An example of this type of fuel injection device is proposed by the applicant in Japanese Patent Application No. 2-77286. This device will be described with reference to FIG. 2. Reference numeral 1 is a fuel pump, 2 is a first fuel pressure regulator for converting the intake manifold pressure P _m into a fuel pressure P ₁ , and a negative pressure chamber to which the intake manifold pressure P _m is applied. 3 and the first fuel chamber 4 to which fuel is supplied from the fuel pump 1 are partitioned by the diaphragm 5 that is elastically pressed by the spring 5a, and the first fuel chamber 4 is provided with an outlet 4a for fuel return. And is opened and closed by a leak valve 5b that is integral with the diaphragm 5. Reference numeral 6 denotes a second fuel pressure regulator connected to the first fuel pressure regulator 2 via the fuel passage 7, and includes an atmospheric pressure chamber 8 to which the atmospheric pressure P ₀ is applied and a fuel flowing from the first fuel chamber 4. The second fuel chamber 9 which sets the fuel pressure to a constant pressure P ₂ (<P ₁ ) and returns the fuel is partitioned by the diaphragm 10 elastically pressed by the spring 10a. Further, the second fuel chamber 9 is provided with an outlet 9a for fuel return, and is opened / closed by a leak valve 10b integral with the diaphragm 10.

Reference numerals 12 and 13 denote a first solenoid valve and a second solenoid valve, which are disposed in the fuel passage 7 and control the opening area of the fuel passage 7 according to the engine speed, respectively. When the same pulse signal is input from the control unit, when this pulse signal is HIGH, the first solenoid valve 12 is closed, the second solenoid valve 13 is open, and when it is LOW, the first solenoid valve 12 is open. The second solenoid valve 13 is closed, and the second solenoid valve 13 is opened and closed in reverse. As shown in FIG. 3, the duty ratio (frequency of pulse signal) of the first solenoid valve 12 and the second solenoid valve 13 is determined according to the engine speed, and the fuel passage between the solenoid valves 12 and 13 is determined. The fuel pressure of No. 7 is taken out as the fuel pressure P ₃ according to the intake manifold pressure P _m and the engine speed.

Reference numeral 14 is a third fuel pressure regulator for converting the fuel pressure P ₃ into an adjusted fuel pressure P ₄ (<P ₃ ), and the first fuel pressure chamber 15 to which the above-mentioned fuel pressure P ₃ is applied and a constant return. The second fuel pressure chamber 16 controlled by the regulated fuel pressure P ₄ according to the fuel pressure P ₃ is introduced by the diaphragm 17 to supply the fuel to the second fuel pressure chamber 16. An outlet 16a for returning to the source and a spring 17a for elastically pressing the diaphragm 17 toward the first fuel pressure chamber 15 are provided. Therefore, the rate of change of the adjusted fuel pressure P ₄ with respect to the fuel pressure P ₃ can be reduced. The return outlet 16a is opened and closed by a leak valve 17b which is integral with the diaphragm 17.

Reference numeral 20 denotes a fuel injection valve which is arranged in each cylinder and whose fuel injection amount to the intake manifold is controlled. Reference numeral 21 denotes a fuel injection valve 20 from the first fuel chamber 4 of the first fuel pressure regulator 2. A metering jet for measuring the fuel flow rate Q ₁ . In the fuel injection valve 20, 22 is an upstream chamber which is supplied with a fuel flow rate Q ₁ from a metering jet 21 and has a discharge port 22a capable of injecting an injection flow rate Q ₂ to an intake manifold, and 23 is a third fuel pressure regulator 14 Of the second fuel pressure chamber 16 to send a constant flow rate Q ₃ and a downstream chamber to which the regulated fuel pressure P ₄ is applied, 24 is a diaphragm separating the upstream chamber 22 and the downstream chamber 23, and 25 is the upstream chamber 22 and the downstream chamber. A differential pressure jet that communicates with the chamber 23, 26 is a valve that controls the opening and closing of the discharge port 22a in conjunction with the diaphragm 24, and 24a is a spring that elastically presses the diaphragm 24 in the valve closing direction of the valve 26. P ₅ is controlled so that the sum and balance of the load adjusting fuel pressure P ₄ and the spring 24a. Therefore, the differential pressure (P ₅ -P _4), i.e., the pressure loss of the differential pressure jet 25 is controlled to be constant, the fuel flow rate Q ₁ is equal to the sum of the injection flow rate Q ₂ and a constant fuel return flow Q _3.

The fuel injection device described above operates as follows. When the intake manifold pressure P _m is converted to the fuel pressure P ₁ when the engine is operating and is sent to the fuel passage 7, the first and second solenoid valves 12 and 13 have a duty ratio corresponding to the engine speed as described above. Determined and controlled to open and close. Therefore, the fuel pressure P ₃ generated between the solenoid valves 12 and 13 decreases when the intake manifold hold pressure is high, regardless of the engine speed. However, when the intake manifold pressure approaches atmospheric pressure, this fuel pressure P ₃ increases.

By the way, the required fuel amount of the engine is proportional to the product of the engine speed and the air density of the intake manifold, but the air density should be replaced with the pressure, that is, the pressure difference (P ₁ −P ₂ ). You can Therefore, the number of applications of the fuel pressure P ₁ to the third fuel pressure regulator 14 (frequency of the first and second solenoid valves 12, 13) is adjusted according to the engine speed, and the obtained fuel pressure P _{3 is set} to the third fuel pressure. The regulator 14 converts the adjusted fuel pressure P ₄ according to the required fuel amount. The adjusted fuel pressure P ₄ increases / decreases in accordance with the increase / decrease in intake manifold pressure, and the rate of change thereof is constant as the engine speed increases / decreases. Then, in the fuel injection valve 20, the fuel pressure P _{5 of the} upstream chamber 22 changes according to the increase or decrease of the fuel pressure P ₄ of the downstream chamber 23. On the other hand, since the fuel flow rate Q ₁ passing through the metering jet 21 is determined by the differential pressure (P ₁ -P ₅ ) across the metering jet 21, the fuel flow rate Q ₁ decreases and increases as the adjustment fuel pressure P ₄ increases and decreases. the flow rate of the jet 2 5 is constant at Q _3, the fuel injection quantity _{Q 2 (= Q 1 -Q 3} ) will vary in accordance with the adjustment fuel pressure P _4. Therefore, the fuel injection amount Q ₂ matches the above-mentioned required fuel amount.

[0008] Incidentally, the fuel flow rate to Q ₁ metering jet 21 will vary in proportion to the square root of the differential pressure (P ₁ -P _5), as the fuel flow rate Q _1, the return is the constant flow rate Q _{If 3} is added to the fuel injection amount Q ₂ in advance, a portion where the fuel injection amount Q ₂ changes linearly with respect to the differential pressure (P ₁ -P ₅ ) can be taken out. Therefore, relates to a fuel flow rate Q ₁ and the differential pressure across the metering jet _{2 1 (P 1 -P 5)} , it is possible to obtain a sufficient dynamic range for automotive.

[0009]

[Problems to be solved by the device]

By the way, in the above-mentioned fuel injection device, if fuel leaks from the leak valve seats of the fuel pressure regulators 2, 6 and 14 after the engine is stopped, the fuel pressures on the downstream side of the fuel pump decrease. For example, if fuel leakage occurs in the closed first solenoid valve 12, the fuel pressure P ₃ decreases and P ₃ = P ₁ , so the diaphragm 17 is displaced by the spring load of the spring 17a, and the fuel return outlet 16a. In this case, the valve opening rate of the leak valve 17b becomes large. In particular, at high temperatures, the fuel inside the equipment rises in temperature and vaporizes, and the generated vapor pushes the fuel out to the return passage, making it impossible to maintain the fuel pressure of each fuel pressure regulator at a certain level. It may run out of fuel.

When the engine is restarted from such a state and the engine key is turned on, the fuel fed from the fuel pump 1 includes the first fuel chamber 4, the metering jet 21, the upstream chamber 22 and the differential pressure jet. 25 and the downstream chamber 23 and the second fuel pressure chamber 16 are filled. As described above, there is a problem that it takes a long time to fill the fuel passage with fuel and increase the pressure of each fuel in the device to a pressure required for engine operation.

During this time, in the fuel injection valve 20, the fuel pressure in the upstream chamber 22 rises before the fuel pressure in the downstream chamber 23, and the differential pressure between the two chambers 22 and 23 is the differential pressure in the above-mentioned balanced state. a size exceeding (P ₅ -P _4). As a result, the diaphragm 24 is displaced toward the downstream chamber 23 side against the spring load of the spring 24a, the valve 26 is opened, and the fuel is discharged from the discharge port 22a. Such initial fuel discharge at restart is maintained until the fuel pressure in each part of the device becomes normal. Therefore, the air-fuel ratio of the air-fuel mixture becomes too rich at the time of restart, and this may also impair the restartability.

In view of the above problems, the present invention aims to improve the restartability by maintaining the fuel pressure when the engine is stopped and preventing the initial fuel discharge when the engine is restarted. The purpose is to provide the device.

[0013]

[Means for Solving the Problems]

 The fuel injection device according to the present invention includes a first fuel pressure regulator for generating a fuel pressure corresponding to the intake manifold pressure, a fourth fuel pressure regulator for generating a fuel pressure lower than the fuel pressure and corresponding to the intake manifold pressure, and a constant fuel pressure. Two opening area settings are provided in the fuel passage connecting the second fuel pressure regulator to be generated and the fourth and second fuel pressure regulators, and the opening area can be adjusted between them to adjust the opening area according to the intake manifold pressure and the engine speed. Means, a first fuel pressure chamber to which a fuel pressure corresponding to the intake manifold pressure and the engine speed is applied, and a second fuel pressure chamber in which the fuel pressure of the first fuel chamber is converted to a regulated fuel pressure are separated by a diaphragm. And a third fuel pressure leg in which the diaphragm is elastically pressed toward the second fuel pressure chamber by a spring. Rater and is obtained by, characterized in that the fuel injection valve the fuel injection amount is controlled according to the adjustment fuel pressure is provided.

[0014]

[Action]

 When the engine is operating, a fuel pressure is generated in the first fuel pressure regulator according to the intake manifold pressure, and a fuel pressure lower by a certain value than this is generated in the fourth fuel pressure regulator. The fuel pressure of the fourth fuel pressure regulator passes through one of the opening area setting means whose opening area is controlled according to the engine speed, and is set as the fuel pressure according to the engine speed and the intake manifold pressure to the third fuel pressure regulator. It is applied to the first fuel pressure chamber. In the third fuel pressure regulator, the adjusted fuel pressure is set in the second fuel pressure chamber so as to balance with the sum of this fuel pressure and the spring load, and the fuel injection amount in the fuel injection valve is controlled. When the engine is stopped, even if the fuel pressures in the system drop and become equal, in the third fuel pressure regulator, the spring displaces the diaphragm toward the second fuel pressure chamber and closes the return outlet. The outflow of fuel is suppressed, the drop of each fuel pressure in the equipment is suppressed, and each fuel pressure is maintained at a certain height.

[0015]

【Example】

 FIG. 1 shows an embodiment of the present invention. The same reference numerals are used for the same parts as those in the above-mentioned prior art, and the description thereof is omitted. The first fuel pressure chamber 15 and the second fuel pressure chamber 16 of the third fuel pressure regulator 14 are partitioned by a diaphragm 17, and the first fuel pressure chamber 15 is spring-pressed to the diaphragm 17 toward the second fuel pressure chamber 16. 17a is provided, which is a so-called normally closed system. The second fuel pressure chamber 16 has a return fuel outlet 16a that is opened and closed by a leak valve 17b that is integral with and interlocks with the diaphragm 17. A fuel bypass 31 from the first fuel chamber 4 of the first fuel pressure regulator 2 is connected to the second fuel pressure chamber 16, and a fuel inflow valve 28 opens and closes this connection port. The leak valve 17b and the fuel inflow valve 28 are connected by an elastic member 30 supported by a guide (not shown) provided in the return fuel passage. 28a is an adjuster including an adjusting screw and a spring, which applies a predetermined load to the fuel inflow valve 28 via the spring, and the amount of strain of the elastic member 30 balances the clearance of the leak valve 17b and the fuel inflow valve 28. It is supposed to be adjusted. Incidentally, 32 is a main fuel passage for the fuel bypass 31.

Reference numeral 33 denotes a fourth fuel pressure regulator, which includes a negative pressure chamber 34 to which intake manifold pressure is applied and a third fuel chamber 1 to which fuel is supplied from the fuel pump 1 through a fuel passage 37 having an orifice 38 therein. The diaphragm 35 is separated from the diaphragm 35. An outlet 35a for returning fuel is provided in the third fuel chamber 35, and is opened / closed by a leak valve 36b which is integral with the diaphragm 36. Further, the negative pressure chamber 34 is provided with a spring 36a that elastically presses the diaphragm 36 toward the third fuel chamber 35. The fuel pressure P ₁ ′ generated in the third fuel chamber 35 of the fourth fuel pressure regulator 33 according to the intake manifold pressure is adjusted so as to be reduced by a constant value as compared with the fuel pressure P ₁ of the first fuel pressure regulator 2. This adjustment is made by using the inside of the orifice 38 and the springs 5a and 36a having appropriate spring constants and spring characteristics.

In the present embodiment configured as described above, the fuel pressure P ₁ is generated in the first fuel pressure regulator 2 according to the intake manifold pressure P _m when the engine is operating, and the fourth fuel pressure regulator 33 is operated in the fourth fuel pressure regulator 33. A fuel pressure P ₁ ′ (<P ₁ ) lower than the fuel pressure P ₁ by a constant value is generated. This fuel pressure P ₁ ′ is applied between both solenoid valves 12 and 13 according to the engine speed, and fuel pressure P ₃ ′ is generated. This fuel pressure P ₃ ′ is applied to the first fuel pressure chamber 15 of the third fuel pressure regulator 14, and the sum of the fuel pressure P ₃ ′ and the spring load of the spring 17 a becomes the adjusted fuel pressure P ₄ in the second fuel pressure chamber 16. It is increased and transformed. Since the adjusted fuel pressure P ₄ is the same as that of the above-mentioned prior art, the injection flow rate Q ₂ is also controlled in the same manner.

During engine operation, the constant flow rate Q ₃ returned through the differential pressure jet 25 and the indefinite flow rate Q ₁ ′ flowing through the fuel bypass 31 are transferred to the second fuel pressure chamber 16 of the third fuel pressure regulator 14. It flows in and is returned from the outlet 16a to the fuel supply source. Then, the valve opening rates of the leak valve 17b and the fuel inflow valve 28, in which the amount of strain is applied to the elastic member 30 by the adjuster 28a and the clearance balance is adjusted, are the fuel pressure P ₃ ′, the adjusted fuel pressure P ₄ , the constant flow rate Q ₃ , It is in equilibrium with the indefinite flow rate Q ₁ ′. Therefore, for example, when the first solenoid valve 12 is closed and the second solenoid valve 13 is open, the fuel pressure P ₂ ′ in the second fuel chamber 9 of the second fuel pressure regulator 6 becomes the engine speed. Accordingly, the fuel pressure is applied between the solenoid valves 12 and 13, and the fuel pressure P _2t (<P ₂ ′) is generated. This fuel pressure P _2t is applied to the first fuel pressure chamber 15 of the third fuel pressure regulator 14. The second fuel pressure chamber 16 is connected to the first fuel chamber 4 of the first fuel pressure regulator 2 via the fuel bypass 31, and as described above, the fuel pressure P ₁ of the first fuel chamber 4 is the second fuel pressure regulator 2 Is larger than the fuel pressure P ₂ ′ of the second fuel chamber 9, the diaphragm 17 is displaced in the direction of the first fuel pressure chamber 15 against the elastic pressure of the spring 17a. Accordingly, the valve opening rate of the leak valve 17b increases, while the valve opening rate of the fuel inflow valve 28 decreases, and the fuel in the second fuel pressure chamber 16 of the third fuel pressure regulator 14 decreases.

When the engine is stopped, the fuel pressures P ₁ , P ₄ , P ₅ decrease and become equal to each other, and both solenoid valves 12, 13 are closed. In principle, the fuel pressure in the first fuel pressure chamber 15 of the third fuel pressure regulator 14 does not decrease and is maintained at P ₃ ′, but if the fuel leaks from the second solenoid valve 13 and the fuel pressure P ₃ ′ changes to another value. Even if the fuel pressure is reduced to the same level as the fuel pressure, since the spring load of the spring 17a is acting, the return outlet 16a is closed by the leak valve 17b integrated with the diaphragm 17 which is displaced in the direction of the second fuel pressure chamber 16. The fuel pressure inside the device can be maintained at a certain level.

Although the first and second solenoid valves 12 and 13 each constitute an opening area setting means, the opening area setting means is not limited to the solenoid valve and may be electrically operated by using a stepping motor or the like. The opening area may be increased or decreased. Alternatively, one of the two opening area setting means may be configured as a jet.

[0021]

[Effect of the device]

 As described above, according to the present invention, the diaphragm is elastically biased by the spring toward the outlet for the fuel return of the second fuel pressure chamber, and the normally closed third fuel pressure regulator and the first fuel pressure according to the intake manifold pressure. By having a fourth fuel pressure regulator that generates a fuel pressure that is lower than the fuel pressure generated by the regulator by a fixed value, aspects such as maintaining fuel pressure when the engine is stopped and preventing initial fuel discharge during restart are improved. The nature is improving.

[Brief description of drawings]

FIG. 1 is a schematic view of an embodiment of a fuel injection device according to the present invention.

FIG. 2 is a schematic diagram of a fuel injection device in the prior art.

FIG. 3 is a diagram showing a relationship between an engine speed and a cycle of a pulse signal.

[Explanation of symbols]

 2 1st fuel pressure regulator 6 2nd fuel pressure regulator 7 Fuel passage 12 1st solenoid valve 13 2nd solenoid valve 14 3rd fuel pressure regulator 15 1st fuel pressure chamber 16 2nd fuel pressure chamber 17 Diaphragm 17a Spring 20 Fuel injection valve 33 4th fuel pressure regulator

Claims (1)

[Scope of utility model registration request] 1. A first fuel pressure regulator for generating a fuel pressure according to the intake manifold pressure, a fourth fuel pressure regulator for generating a fuel pressure lower than the fuel pressure according to the intake manifold pressure, and a second fuel pressure for generating a constant fuel pressure. A regulator and two opening area setting means provided in a fuel passage connecting the fourth and second fuel pressure regulators and capable of adjusting an opening area according to the intake manifold pressure and engine speed from between the intake passage and the intake manifold; The first fuel pressure chamber to which the fuel pressure corresponding to the pressure and the engine speed is applied and the second fuel pressure chamber in which the fuel pressure of the first fuel pressure chamber is converted into the adjusted fuel pressure are partitioned by a diaphragm, and the diaphragm is separated by a spring. A third fuel pressure regulator that is elastically pressured toward the second fuel pressure chamber, and the adjusted fuel A fuel injection device, comprising: a fuel injection valve whose fuel injection amount is controlled according to pressure.