JPS6332160A - Fuel supply device - Google Patents

Abstract

PURPOSE:To prevent boiling under reduced pressure at the time of high- temperature starting in a high-temperature start adjusting mechanism, by providing a throttle part in the port of a negative pressure chamber, and making the return spring energizing a diaphragm vacuum with a shape-memory alloy. CONSTITUTION:A high-temperature start adjusting mechanism 2 is provided inside a housing 18. The housing 18 is partitioned into a negative pressure chamber 108, an auxiliary negative pressure chamber 104, and an atmospheric pressure chamber 103. A port 20 has e throttle part 20a, and a return spring 16 Which energizes a diaphragm vacuum 13 is made of a shape-memory alloy. When an engine is started, the internal pressure in a manifold becomes suddenly a negative pressure, however, since the throttle 20a is provided, the internal pressure in the negative pressure chamber 106 is not suddenly reduced. Thus, thc pressure inside a fuel high-pressure chamber 109 is maintained in a high value to supply sufficient fuel to injection valves 4, enabling boiling under reduced pressure to be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to fuel pressure control of an engine equipped with an electronically controlled fuel injection device used in automobiles and the like.

[Prior Art] In a fuel injection engine, the fuel temperature may rise due to heat in the engine room after the engine is stopped. For example, after high-speed operation, when the engine stops and the radiator fan stops, the temperature inside the engine and engine compartment will rise rapidly, and the fuel remaining in the injectors and fuel pipes will tend to become hot. have When the fuel temperature increases or the fuel pressure decreases, the fuel vaporizes and a so-called reduced pressure boiling phenomenon occurs. Particularly in a state where the intake pipe negative pressure is high, this phenomenon occurs in a large amount near the metering section of the fuel injection valve, and the desired amount of fuel supply may not be secured. Therefore, it may be difficult or impossible to restart the engine when the fuel temperature is high.

In an engine equipped with an electronic fuel injection system, a fuel pump installed in the fuel supply system from the fuel tank to the injector adjusts the fuel pumped under pressure to the intake manifold to a predetermined value. Pressure regulator is 1. It is installed between the fuel return line connected to the fuel tank and the injector. This pressure regulator uses a diaphragm that operates in response to the negative pressure in the intake manifold to return a portion of the fuel to the fuel tank in proportion to the negative pressure, so that it is injected from the injection valve into the intake manifold. Control the amount of fuel? ff1l.

In this way, conventional pressure regulators use the manifold negative pressure as a control index, so if the manifold negative pressure suddenly increases when the engine is started,
The return line opens and a large amount of fuel is returned to the fuel tank, and as a result, the pressure of the fuel being pumped decreases, and if the fuel temperature is high, the aforementioned reduced pressure boiling phenomenon occurs in the injector foot section. It becomes easy.

To prevent this, when the fuel temperature is high, when starting the engine, close the line leading to the negative pressure in the manifold so that it does not act on the pressure regulator, and instead introduce atmospheric pressure into the pressure regulator. All you have to do is switch. Then, after the engine starts, the engine temperature is normalized by the action of the radiator fan, and when the fuel temperature has also dropped, the switch is switched to introduce the negative pressure of the manifold into the regulator again, and the normal fuel pressure corresponding to the negative pressure is restored. All you have to do is restore control.

[Structure of the invention]

The present invention provides a simple fuel pressure control device that can perform operations during high-temperature startup with a single actuator, from temperature detection to a timer function that determines when to reintroduce manifold negative pressure. The purpose is to provide.

That is, the present invention includes a fuel supply path from a fuel tank to an injector that injects fuel through a fuel pump, and a fuel return pipe for returning fuel in the fuel supply path that is not injected by the injector to the fuel tank. In the fuel injection engine, the pressure regulator has a pressure regulator that is vertically separated into a negative and positive chamber and a fuel high pressure chamber by a diaphragm. The negative pressure chamber is provided with a port for introducing the negative pressure of the intake manifold, and the fuel high pressure chamber is provided with a fuel port for receiving fuel from the fuel supply path, and an output robot connected to the fuel return pipe. A closing means pressed by the diaphragm and a spring provided in the negative pressure chamber that exerts a pressing force on the diaphragm is engaged with the internal opening of the outlet port, so that the fuel introduced into the high fuel pressure chamber is When the pressure of The pressure regulator is configured to allow fuel in the fuel high pressure chamber to escape to a fuel return pipe through the port, and the pressure regulator further includes a temperature sensitive actuating member such that when the fuel temperature is above a predetermined temperature, the pressure regulator A fuel supply device for an internal combustion engine, comprising a high-temperature start adjustment mechanism configured to cut off a conduit that introduces negative pressure into the negative pressure chamber and to make the conduit conductive again after a predetermined period of time. It is.

The actuating member undergoes deformation below a predetermined temperature;
It consists of a plunger fixed to a diaphragm that is biased by a compression spring made of a shape memory alloy that becomes elastically deformed when the temperature exceeds a predetermined temperature, and the plunger is biased by this when the spring becomes elastic during high temperature startup. occupies a first position where the manifold negative pressure introduction conduit is shut off, and when the pressure in the negative pressure chamber decreases to a predetermined negative pressure or more, the manifold occupies a second position where the conduit is conducted; A constricted conduit that communicates with the manifold is connected to the conduit in parallel to the negative pressure chamber, and when the plunge portion occupies a first position, the negative pressure in the intake manifold is connected to the conduit through the constricted conduit. The diaphragm is configured to gradually introduce pressure into the negative pressure chamber, and when the pressure in the negative pressure chamber reaches a predetermined negative pressure or more after a predetermined time, the diaphragm responds to this and reduces the biasing force of the spring. It is preferable that the pressure regulator be moved upwardly to push the shaft down to the second position and return the pressure regulator to a normal operating state.

〔Example〕

Hereinafter, the present invention will be explained in more detail based on preferred embodiments shown in the drawings.

FIG. 1 is a duct diagram of a fuel supply system for an internal combustion engine incorporating the pressure regulator of the present invention.

The fuel that is pumped through the pipe 3 by the fuel pump (not shown) is injected from the injection valve 4 into the intake manifold, and the remaining amount enters the pressure regulator 1, from where it passes through the return pipe 5 to the fuel tank (not shown). (not).

The main body of the pressure regulator 1 is the diaphragm 2.
4, and below the diaphragm 24 is a fuel high pressure chamber 109 equipped with a port 35 for receiving fuel from the fuel supply pipe 3 leading to the injection valve l.
Moreover, the upper part of the diaphragm 24 constitutes a negative pressure chamber 10B having a port 19 that communicates with the intake manifold via a high temperature start adjustment mechanism 2 which will be described later. The diaphragm 24 and the upper partition wall 112 of the pressure regulating section 30
A normal type return spring 21 is interposed between the diaphragm 24 and the diaphragm 24 to urge the diaphragm 24 downward. Further, a closing member 29 is fixed below the diaphragm 24 and engages with the internal opening of the port 32 communicating with the return pipe 5 which enters the fuel high pressure chamber 109 so as to be openable and closable. With this configuration, when the internal pressure of the negative pressure chamber 108 decreases, that is, when the internal pressure of the intake manifold decreases, the diaphragm 24 rises to open the port 32 and the fuel high pressure chamber 1
The fuel in 09 flows into the return pipe 5, and conversely, when the internal pressure rises, it descends to block the port 32 and stop the flow of fuel. The configuration of the pressure regulator I described above is substantially the same as that of the prior art.

The feature of the present invention lies in the high temperature start adjustment mechanism 2 provided at the upper part of the pressure adjustment section 30. That is, the adjustment mechanism 2 is provided within a housing 18 fixed on the partition wall 112. The housing 18 is divided into three parts, upper and lower. It is classified as 103. The atmospheric pressure chamber 103 is:! The hole 102 provided in the I'l wall communicates with the outside air and maintains atmospheric pressure at all times. A control chamber 106 is provided above the atmospheric pressure chamber 103 and is airtightly separated from the chamber 103.

The control chamber 106 further includes a large-diameter lower control chamber 106b.
And upper system of small diameter? fftl room 106a.

A return spring 15 is interposed between the diaphragm vacuum 13 and the partition wall 112, and is configured to bias the diaphragm vacuum 13 from below. Further, the base of a vertically provided valve shaft 11 is fixed to this diaphragm vacuum 13, and as the diaphragm vacuum 13 moves up and down, the inside of the control chamber 106 passes through a sliding hole 120 bored in the bottom wall of the control chamber 106. It is configured so that its tip protruding from the top can be raised and lowered. It is necessary that the hole 120 and the shaft 11 are fitted in an airtight manner.

The tip of the shaft 11 is formed into a tapered shape, and when raised, the upper control chamber 106
Both upper and lower in airtight contact with the lower inlet of b: bll Cylinder chamber 1
06a and 106b are separated. Father's control room 106a
has a port 16 in its side wall, which port 16 communicates with the intake manifold. Kawa Rira 8 Pig Port 16
The pressure in the intake manifold passes through the upper control chamber 1
06a. On the other hand, a port 17 is provided on the side wall of the lower control chamber 106b, and is connected to one port provided in the negative and positive chamber 108 through a conduit 2b. For this reason, the lower control room 106b
The internal pressure of the negative pressure chamber 108 is maintained the same as that of the negative pressure chamber 108.

Furthermore, a characteristic feature of the high temperature start adjustment mechanism 2 of the present invention is that another port 20 is provided in the negative pressure chamber 108, and the internal pressure of the intake manifold is introduced through the conduit 2b. +OL This port 20 is the throttle part 20a
Therefore, the internal pressure of the negative pressure chamber 108 changes only very gradually. Another feature of the present invention is that the return spring 15 that biases the diaphragm vacuum I3 of the high-temperature start adjustment mechanism 2 is made of a known shape memory alloy containing Ni-Ti as its main component. , it exhibits elastic properties above a certain temperature, but below that temperature it behaves plastically. This predetermined temperature is set, for example, to 50'C, at which there is a possibility that fuel decompression may occur.

Next, the operation of this high temperature start adjustment mechanism 2 will be explained. After a certain period of time has passed since the engine stopped, the internal pressure of each part including the negative pressure chamber becomes equal to atmospheric pressure. For the reasons mentioned at the beginning, the fuel temperature and therefore mechanism 2
If the temperature of each part inside rises above the specified temperature,
The spring 15 exhibits an elastic behavior and automatically pushes the diaphragm vacuum 13 upward against the pressure in the atmospheric pressure chamber 103. As a result, the valve shaft 11 moves upward and closes the inlet of the upper control chamber 106a, and the lower control chamber 106a closes the inlet of the upper control chamber 106a.
The adjustment action is started by cutting off the communication with 6b. Since the upper and lower control chambers 106a and 106b are separated, the pipe line 2b leading to the port 19 that introduces the internal pressure of the intake manifold into the negative pressure chamber 108 is blocked, and the
Inside, only the conduit 2a leading to the port 20 is open. When the engine is started in this state, the internal pressure of the manifold suddenly becomes negative, but since the port 20 is equipped with the throttle 20a, the internal pressure of the negative pressure chamber 108 does not decrease rapidly and becomes substantially atmospheric pressure. It will remain as it is. Therefore, the pressure regulating section 30 operates in the same manner as when the internal pressure of the intake manifold is high, and as a result, the pressure within the fuel high pressure chamber 109 is maintained at a high value, and sufficient fuel is supplied to the injection valve 4.
Reduced pressure boiling phenomenon is prevented.

With the passage of time, the negative pressure chamber 10 through the port 20
8's internal pressure gradually decreases. Therefore, the internal pressure of the auxiliary negative pressure chamber 104, which is in communication with the auxiliary negative pressure chamber 104 through the communication hole 105, also decreases, and when this value drops to a predetermined value, the difference between the internal pressure of the atmospheric pressure chamber 103 causes the biasing force of the return spring 15. , that is, F<A・P (where F is the preset load due to the spring 15, and A
is the effective area of diaphragm vacuum 13.

P represents the pressure in the auxiliary negative pressure chamber 104) When the following holds true, the diaphragm vacuum 13 is displaced downward. As a result, the valve shaft 1 also descends, releasing the isolation between the upper and lower control chambers 106a and 1QSb. As a result, Bo)16. Upper and lower control chambers 106a, 10
6b, port 17. The passage constituted by the pipe line 2b and the port 19 is opened, and the negative pressure of the intake manifold is directly introduced into the negative pressure chamber 108, and the pressure therein is rapidly reduced.

As a result, normal control of the fuel supply pressure is started.

At this point, the fuel temperature has dropped to the normal value due to engine idling, so return spring 1
5 shows plastic behavior and valve shirt in lowered position)
11, and the upper and lower control chambers 106a, 10
6b is maintained in constant communication. Port 20 aperture 2
By appropriately setting 0a, it is possible to adjust the time for the internal pressure of the negative pressure chamber 108 to drop to a predetermined value, and to adjust this time to match the time for the fuel temperature to drop to a predetermined value due to idling. If set to , the initial objective will be achieved. The above explanation will be further understood by looking at the changes in pressure at various parts over time shown in FIGS. 2 to 4.

In the high temperature start adjustment mechanism of the present invention, instead of the above-mentioned clean spring 15 made of a shape memory alloy, a normal bias spring 200 as shown in FIGS. 5 and 6 and a thermowax 201 that melts at a predetermined temperature are used. It is also possible to use a combination of. Under normal conditions (at low temperatures), the valve shaft 11 fixed to the diaphragm vacuum 13 is pressed down against the bias spring 200 acting on the diaphragm vacuum 13, and its base is fixed in thermowax 201. It is retained (Fig. 5). In this state, the tip of the shaft 11 is far away from the upper control chamber 106a, and the two split cylinder chambers 106a,
106b communicate with each other. However, as shown in Figure 6, what happens to Thermowax 201 when starting at a high temperature? Since the valve shaft 11 is molten, the bias spring 2
It rises due to the urging force of 00, and the two divided cylinder chambers 106a, 10
6b communication is cut off.゛The holding force of the thermowax 201 is Ft, and the biasing force of the bias spring 200 is Fs.

If the force of the diaphragm vacuum 13 is Fd, then Ft
When the relationship <Fs+Fd holds true, the valve is opened and the two divided cylinder chambers communicate with each other.

As another example, it is also possible to use a snap-action bimetal instead of the shape memory alloy spring L5.

Furthermore, in each of the above-mentioned sides, the high temperature start adjustment mechanism was integrally attached to the pressure regulator;
This may be installed separately.

[Brief explanation of the drawing]

Fig. 1 is a side sectional view of the high temperature start adjustment mechanism of the present invention integrated with a pressure regulator, Figs. 5 and 6 are side sectional views showing the main parts of the second embodiment of the high temperature start adjustment mechanism of the present invention, respectively, when the valve is closed and when it is opened. 10...Vacuum upper case 11-...Valve shaft 13...Diaphragm vacuum 15--Return spring 16.17, 19.20--Port 18--Vacuum lower case 21--Return spring 30... Adjustment Pressure section 102--Atmospheric communication hole 103--Atmospheric pressure chamber 104--Auxiliary negative pressure chamber 105--Series communication hole 106a--Upper control chamber 106b--Lower control chamber 108--Negative pressure Chamber 109 - Fuel high pressure chamber 1 ↓ Fuel port/f Fuel tank Figure 1 Figure 2 Figure 3

Claims (2)

[Claims] 1. a fuel supply path from a fuel tank to an injector that injects fuel through a fuel pump; a fuel return pipe for returning fuel in the fuel supply path that is not injected by the injector to the fuel tank; and a fuel return pipe in the fuel supply path. In a fuel injection engine, the pressure regulator has a pressure regulating section vertically separated into a negative pressure chamber and a fuel high pressure chamber by a diaphragm, and the negative pressure chamber has a A port is provided for introducing the negative pressure of the intake manifold, and the fuel high pressure chamber is provided with a fuel port for receiving fuel from the fuel supply passage, and an outlet port communicating with the fuel return pipe, and a nuclear outlet port. A closing means pressed by a spring provided in the negative pressure chamber that applies a pressing force to the diaphragm is engaged with the internal opening of the diaphragm, and the pressure of the fuel introduced into the fuel high pressure chamber is applied to the diaphragm. When the negative pressure in the negative pressure chamber acting on the negative pressure becomes higher than the sum of the force of the spring, the engagement between the closing means and the internal opening of the outlet port is released;
The pressure regulator is configured to allow fuel in the fuel high pressure chamber to escape to a fuel return pipe through the outlet port, and the pressure regulator further includes a temperature-sensitive actuating member, and the actuating member causes the pressure regulator to operate when the fuel temperature is above a predetermined temperature. A fuel for an internal combustion engine, comprising a high-temperature start adjustment mechanism configured to cut off a line that introduces negative pressure of a manifold into a negative pressure chamber, and to make the line conductive again after a predetermined period of time. Feeding device. 2. The actuating member consists of a plunger fixed to a diaphragm biased by a compression spring made of a shape memory alloy that undergoes plastic deformation below a predetermined temperature but turns into elastic deformation above a predetermined temperature. When the spring is elastic, it is biased and assumes a first position that cuts off the manifold negative pressure introduction pipe, and when the pressure in the negative pressure chamber decreases to a predetermined negative pressure or higher, the pipe a conduit with a throttle that communicates with the manifold is connected to the negative pressure chamber in parallel with the conduit, and the plunger occupies the first position; The negative pressure in the intake manifold is gradually introduced into the negative pressure chamber through the constricted conduit, and when the pressure in the negative pressure chamber reaches a predetermined negative pressure or more after a predetermined time, the In response, the diaphragm pushes down the shaft to the second position by exceeding the biasing force of the spring and returns the pressure regulator to a normal operating state. Device.