JP2590927B2 - Fuel pressure control device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a pressure control device, and particularly to a fuel pressure control device used for a fuel injection device for an internal combustion engine. The device of the present invention is used, for example, in a fuel injection device of an automobile engine.

2. Description of the Related Art Conventionally, as a fuel pressure control device (hereinafter, also simply referred to as a fuel pressure control valve) of a fuel injection device for an internal combustion engine, one that controls a fuel supply pressure by a fuel temperature has been proposed. For example, the fuel pressure control valve described in Japanese Patent Application Laid-Open No. 54-28933 has an electromagnetic valve section, and controls the electromagnetic valve section based on the temperature of cooling water to control the fuel flow returning to the fuel tank.

In the fuel pressure control valve described in Japanese Patent Application Laid-Open No. 52-148729, a second valve portion for temperature control is provided in a discharge side passage thereof, and the second metal portion is provided by a bimetal provided downstream of the second valve portion. It discloses that the two-valve portion is mechanically operated to control the fuel discharge pressure. The fuel pressure control valve is a valve for keeping a pressure difference between an intake pipe pressure and a fuel supply pressure of a fuel engine constant, and is generally a diaphragm operated by a differential pressure between the intake pipe pressure and the fuel supply pressure. It is a valve.

The electromagnetic valve portion or the second valve portion incorporated in the fuel pressure valve prevents deterioration of fuel circulation due to generation of bubbles in the fuel pipe due to an increase in fuel temperature. The pressure on the upstream side of the electromagnetic valve or the second valve (ie, the fuel supply pressure to the injector) is increased by squeezing or shutting off the electromagnetic valve or the second valve to prevent the generation of bubbles.

[Problems to be Solved by the Invention] However, in the first prior art using an electromagnetic valve,
A temperature sensor for detecting the temperature of the cooling water and a control circuit for processing the detected signal to output a control signal to the solenoid valve are required, and the configuration is complicated and there is a problem in maintaining reliability.

In the second prior art using a bimetal, the bimetal is installed on the downstream side of the pressure control valve and the second valve, so that either or both of the pressure control valve and the second valve are used. When the fuel flow is interrupted, there is a problem that it is difficult for the bimetal to accurately detect the fuel temperature and that the detection of the temperature change is delayed.

The present invention has been made in view of the above problems, and has as its object to provide a temperature-compensated fuel pressure control valve capable of detecting a fuel temperature more accurately and quickly.

[Means for Solving the Problems] The fuel pressure control device according to the present invention includes an inflow port through which fuel flows, an outflow port through which fuel flows out, a fuel passage connecting the inflow port and the outflow port, and the fuel passage. A first valve having a first valve section provided for controlling a fuel supply pressure in accordance with a pressure difference from an intake pipe negative pressure of the internal combustion engine; and a second valve for controlling the fuel supply pressure in accordance with a fuel temperature. In a fuel pressure control device having two valves, the second valve is provided in the fuel passage so as to be independent and in series with the first valve, and controls a fuel supply pressure. A second valve portion is provided independently of the first valve in the fuel passage between the second valve portion and the inflow port, and mechanically biases the second valve portion when the fuel temperature becomes high. And a temperature sensing part for increasing the fuel supply pressure.

[Operation] In the fuel pressure control device of the present invention, the first valve, which is generally a diaphragm valve, is opened and closed by the differential pressure between the fuel supply pressure and the intake pipe pressure of the fuel injection type internal combustion engine, so that the differential pressure becomes constant. The valve unit (hereinafter, referred to as a first valve unit) is operated so as to be as follows. The temperature sensing part of the second valve is installed on the upstream side of the second valve part. Therefore, regardless of the opening and closing of the second valve portion, the temperature sensing portion maintains contact with the fuel liquid on the upstream side of the second valve portion, expands and contracts according to the fuel temperature, and is arranged in series with the first valve portion.
Activate the valve portion (second valve portion) of the valve. For example, the temperature sensing portion operates in a direction to close the second valve portion as the fuel temperature rises, and as a result, increases the upstream pressure of the second valve portion (for example, the fuel supply pressure to the injector of the fuel injection device). Prevents the generation of air bubbles.

Further, when the temperature sensing portion of the second valve portion is provided on the upstream side of the first valve portion and the second valve portion, the temperature sensing portion is provided regardless of opening and closing of both the first valve portion and the second valve portion. Can be brought into contact with the fuel liquid on the high pressure side.

[Embodiment] Fig. 1 shows an embodiment of the fuel pressure control valve of the present invention.

The control valve includes a housing 3 and a first valve 1 and a second valve 2 built in the housing 3.

The housing 3 includes a hexagonal bolt-shaped metal base 30 and a case 40 attached to one end of the base 30.

The base 30 has a thread 31 at the outer periphery at one end and a hexagonal head 32 at the other end. Further, the base 30 has a through hole 33 extending in the axial direction at the center thereof, and has a fuel discharge port 35 opened in a direction perpendicular to the through hole 33 in a circumferential side wall 34 between the head 32 and the thread 31. In addition, the base 30 has a cylindrical protrusion 36 having a short axis and protruding from the head 32 in a direction opposite to the screw thread 31.

The case 40 includes a first case member 41, a second case member 42, a third case member 43, and a packing 44 which are caulked at the caulking portion 45.

One end of the first case member 41 has a protrusion 36 on the head 32 of the base 30.
Is a thin metal cylindrical member having openings at both ends which is welded and fixed to the other end of the brim-shaped portion and is swaged by a swaging portion 45 to another member such as the second case member 42. The second case member 42 is a thin metal bowl-shaped member whose brim-shaped end is swaged with another member such as the first case member 41 at the swaging portion 45.

One end of the third case member 43 is swaged by another member such as the first case member 41 at the swaging portion 45, and a brim-like shape is disposed inside the second case member 42 substantially parallel to the second case member 42. It is a cylindrical member. The packing 44 is a ring-shaped rubber fitted to the third case member 43 at the caulking portion 45. In addition, the second case member 42 has an inner space (hereinafter referred to as a spring chamber 46) of the second case member 42 and an engine (not shown) on its outer peripheral side wall.
An intake pressure introducing cylinder 50 communicating with an intake manifold (not shown) is fixed by welding.

One end of the first valve 1 is supported at one end by a diaphragm 11 whose outer peripheral edge is crimped to a caulking portion 45 of a case 40, a first valve portion 12 fixed to the diaphragm 11, and a bottom of a bowl of a second case member 42. And a seat 14 to which the first valve portion 12 is fixed and which supports the other end of the spring 13.

The diaphragm 11 is a thin plate made of rubber and resin base cloth having a circular opening at the center.

The first valve portion 12 has a movable valve portion 121 fitted and fixed to the circular opening of the diaphragm 11, a ring-shaped pressing plate 122 fixed to the movable valve portion 121, and a movable valve portion 121 formed by the ring-shaped pressing plate 122.
The valve body 123 pressed and fixed to the
It comprises a coil spring 124 pressed and fixed to 5, and a valve seat 125 described later.

The movable valve portion 121 is a cylindrical member having a short axis, and has a small cylindrical portion 126 at one end thereof, through which the opening of the diaphragm 11 is inserted. Further, the movable valve portion 121 has a groove 127 formed at the center portion thereof and formed at one end opening for accommodating the coil spring 124 formed in the axial direction. The entrance of the groove 127 is tapered.

The annular holding plate 122 has its inner peripheral edge formed by the groove 12 of the movable valve portion 121.
7 is a metal ring that is in contact with the peripheral edge portion of 7, and has its own outer peripheral edge portion caulked and fixed to the movable valve portion 121, and holds the valve element 123 to the movable valve portion 121 as described later. The valve body 123 includes a metal disk portion 128 and a metal ball portion 129 welded to the center of the circular-principal surface thereof. Further, the valve body 123 is movably held by the annular holding plate 122, and the coil spring 124 is moved by the movable valve portion.
It is a member arranged to be pushed into the groove 127 of 121.

The valve seat 125 is a ring-shaped projection formed integrally with one end of the cylindrical base 211 of the second valve portion 21 described later and arranged near the disk portion 128 of the valve body 123.

The second valve 2 includes a second valve portion 21 inserted and fixed in the through hole 33 of the base 30 of the housing 3 and a thermowax 22 for operating the second valve portion.

The second valve portion 21 includes a cylindrical base 211 pressed into the through hole 33 of the hexagonal bolt-shaped base 30 of the housing 3, and a piston 212 and a coil spring 213 housed inside the cylindrical base 211.

The cylindrical base 211 has a valve seat 125 which is a ring-shaped projection at one end, and has an internal through hole communicating with each other in the axial direction at the center.
It is a cylindrical member having both ends opened and having a 214 and a valve hole 215. Further, the cylindrical base 211 has an outlet passage 216 that opens in a direction perpendicular to the valve hole 215 and communicates the valve hole 215 with the fuel outlet 35 of the base 30 of the housing 3.

The internal through hole 214 is a through hole that is surrounded by the valve seat 125 at one end not communicating with the valve hole 215. Further, the cross-sectional shape of the cylindrical base 211 is a partially chamfered circular shape as shown in FIG. 3, and the non-chamfered outer peripheral side of the cylindrical base 211 comes into contact with the through hole 33 of the hexagonal bolt-shaped base 30. I have. The gap between the cylindrical base 211 and the hexagonal bolt-shaped base 30 constitutes a fuel passage 217.

The cylindrical base 211 has a shorter cylinder length than the hexagonal bolt-shaped base 30, and the end of the cylindrical base 211 having the valve seat 125 slightly projects from the end of the hexagonal bolt-shaped base 30 on the protrusion 36 side. As such, the cylindrical base 211 is supported by the hexagonal bolt-shaped base 30.

The coil spring 213 is a member that is housed in the valve hole 215 such that one end is locked to a stepped surface between the valve hole 215 and the internal through hole 214, and the other end biases a piston 212 described later. .

The piston 212 is a member that is slidably housed in the valve hole 215 and one end of which is fixed to the thermowax 22 described later. Further, the piston 212 is opened so that one end thereof communicates with the internal through hole 214, and the other end thereof is the fuel outlet 35.
And a fuel bypass passage 218 opened so as to communicate with the fuel passage. Further, an O-ring 219 for sealing the fuel liquid is fitted in a ring-shaped groove formed on the circumferential side wall of the piston 212.

The thermowax 22 is a sectional view taken along the line BB 'in FIG.
As shown in the figure, a wax-type inflatable member having a substantially rectangular cross-sectional shape is provided.
One end is housed in a ring-shaped projection 37 extending inward from one end of a hexagonal bolt-shaped base 30. As shown in FIG. 2, the four tops of the rectangular section of the thermowax 22
221 is locked in the internal through-hole 214 of the hexagonal bolt-shaped base 30, and a gap therebetween forms a fuel passage 222.

The fuel chamber 500 includes the first case member 41 and the diaphragm 11
And a space surrounded by the movable valve portion 121 and the cylindrical base portion 125.

Further, a circumferential end 281 of the thermowax 22 is locked to one end of the cylindrical base 211 and has a function of separating the fuel passage 222 and the valve hole 215.

The method of assembling the fuel pressure control device will be described below.

First, the valve body 123 is formed by welding the spherical portion 129 and the disk portion 128 of the valve body 123 with the annular holding plate 122 interposed therebetween. Next, valve body 123
The coil spring 124 is pushed into the groove 127 of the movable valve portion 121 by the spherical portion 129, and the outer peripheral edge of the annular holding plate 122 is swaged and fixed to the movable valve portion 121. Next, the diaphragm 11 and the seat 14 are fitted into the small cylindrical portion 126 of the movable valve portion 121, and the outer peripheral surface of the small cylindrical portion 126 is caulked to fix the seat 14, the diaphragm 11, and the movable valve portion 121. Next, one end of the spring 13 is supported on the seat 14, and the diaphragm 11, the first case member 41, the second case member 42, the third case member 43, and the packing 44 are arranged in a predetermined order at respective peripheral portions, The first valve 1 is formed by caulking.

The order of the caulking will be further described. First, the peripheral edges of the diaphragm 11 and the third case member 43 are aligned, and the peripheral edges of the first case member 41 are caulked so as to sandwich them. Next, the packing 44 is inserted into the third case member 43, and the packing 44, the diaphragm 11, the first case member 41, and the third case member 43 are clamped from the side opposite to the second case member 42 so as to be inserted.

Next, the coil spring 213 and the piston 212 attached to the thermowax 22 are inserted into the valve hole 215 of the tubular base 211,
Next, the cylindrical base 211 is press-fitted and fixed in the through hole 33 of the hexagonal bolt-shaped base 30 with the thermowax 22 at the top, and the second valve 2
Assemble

Next, the first case member 41 is fixed to a hexagonal bolt base so that the disk portion 128 of the valve body 123 of the first valve can contact the valve seat 125.
It is fixed to 30 small cylindrical parts 126 by welding.

 The operation of the fuel pressure control device will be described below.

 First, the flow of the fuel will be described below.

This device is installed on the discharge side of a fuel pump (not shown) of a fuel injection type internal combustion engine, and has an injector (not shown).
The fuel discharged from a fuel pump (not shown) flows into the pressure control valve from the X direction in FIG. 1, and flows into the fuel inlet 280, the fuel passages 222 and 21.
Through 7 reach the fuel chamber 500. Further, the fuel in the fuel chamber 500 is provided with a gap between the disc portion 128 of the valve body 123 and the valve seat portion 125 (in FIG. 1, the gap is not shown) and an internal through hole.
Through the fuel passage, valve hole 215, fuel outflow passage 216 which is 214,
The fuel returns to the fuel tank via the fuel outlet 35 and a pipe (not shown).

The intake pressure introducing cylinder 50 of the first valve 1 communicates a spring chamber 46 defined by the diaphragm 11 and the second case member 42 with an intake manifold (not shown) of the engine. Introduce. Diaphragm 11 is a spring chamber
The valve 123 is displaced to a position where the urging force of the differential pressure and the urging force of the spring 13 are balanced by the pressure difference between the intake pressure of 46 and the fuel supply pressure of the fuel chamber 500.

That is, the valve body 123 opens when the fuel supply pressure increases or the intake pressure decreases, and when the differential pressure increases, the valve body 123 opens and the internal through hole 21
The fuel flow returning to the fuel tank (not shown) via the fuel passage (4) is increased, and when the pressure difference is reduced, the fuel tank is closed and the fuel tank (not shown) via the fuel passage (the internal through hole 214) is increased. Reduce the fuel flow returning to

After all, as is well known, the first valve 1 operates to keep the differential pressure constant.

The second valve 2 further controls the flow rate of the fuel flowing out of the fuel outlet 35 according to the fuel temperature in the fuel passage 222.

That is, the thermowax 22 disposed in contact with the fuel in the fuel passage 222 urges the piston 212 according to the fuel temperature on the upstream side of the first valve portion 12 and the second valve portion 21. The piston 212 is displaced to a position where the urging force of the thermowax 22 and the urging force of the coil spring 213 are balanced, and controls the flow rate of the fuel flowing out of the fuel outlet 35. That is, when the fuel temperature in the fuel passage 222 rises, the thermowax 22 expands and presses the piston 212 to displace the second valve portion 21 in a closing direction. Then, when the fuel temperature of the external fuel passage 222 decreases, the thermowax 22 contracts and sucks the piston 212 to displace the second valve portion 21 in the opening direction. Therefore, the second valve 2
Decreases the fuel flow returning to a fuel tank (not shown) when the fuel temperature rises, and increases the fuel supply pressure. As a result, the boiling point of the fuel in the discharge-side path of the fuel pump (not shown) increases, and the generation of fuel bubbles is suppressed.
Even if the first valve 1 and the second valve 2 are closed, the supply pressure (to the injector) is limited by the relief pressure of the fuel pump and does not become excessive. The bypass passage 218 formed in the piston 212 is for improving controllability of the first valve 1, but can be omitted. The same effect can be obtained by providing a bypass groove in the outer peripheral portion of the piston 211 instead of the bypass passage 214.

Further, the coil spring 124 presses the ring-shaped pressing plate 122 held by caulking the peripheral portion to the movable valve portion 121 to the spherical portion 129 of the valve body 123.
Is urged in the valve closing direction via. Therefore, when the disk portion 128 of the valve body 123 comes into contact with the valve seat 125, the coil spring 124 and the ring-shaped pressing plate 122 function as a buffer member, so that the impact force applied to the valve body 123 is reduced.

As described above, according to the present embodiment, the thermowax 22 is supplied to the fuel passage (fuel passage 22) on the upstream side of the first valve portion 12.
2, 217, the fuel chamber 500), even if the first valve portion 12 and the second valve portion 21 are shut off, the fuel liquid in contact with the thermowax 22 is retained, and the fuel temperature is controlled by the liquid transmission. The heat is transferred to the thermowax 22 faster by heat.

In the conventional example in which the bimetal that functions as the second valve is installed downstream of the first valve, when the first valve is shut off, the fuel in contact with the bimetal escapes to the fuel tank, and the temperature-sensitive member Responsiveness deteriorates.

In the embodiment of the present invention, a shape memory alloy spring or bimetal may be used instead of the thermo wax 22 as the temperature sensing part.

Further, the movable valve portion 121 is made of thermo-wax and the valve body 123
May be urged by the thermo wax piston. In this way, the displacement of both the diaphragm 11 and the movable valve portion 121 acts on the valve body 123, so that the first valve portion and the second valve portion can be made common, and the second valve shown in FIG. 2 can be omitted.

[Effects of the Invention] As described above, the fuel pressure control device of the present invention includes the first valve mechanically driven by the pressure difference between the fuel supply pressure and the intake pipe pressure, and the second valve driven by the fuel temperature. With
In addition, since the temperature sensing portion of the second valve for detecting the fuel temperature is provided at least in the fuel passage upstream of the second valve, even when the second valve shuts off the fuel flow, the temperature sensing portion and the fuel are not affected. , The normal temperature change of the fuel is detected, and the second valve for temperature correction can be operated accurately and quickly.

In addition, in the conventional example in which the bimetal is installed in the fuel passage on the downstream side of the first valve portion and the second valve portion, either the first valve portion or the second valve portion only blocks the fuel flow. Therefore, the fuel in contact with the bimetal flows out to, for example, a fuel tank, and as a result, the heat transfer resistance of the bimetal increases, making it difficult to detect a normal and quick fuel temperature.

Further, the fuel pressure control device of the present invention is provided with a valve portion (second valve portion) of a second valve that operates according to the fuel temperature independently and in series with the first valve that operates according to the intake pressure of the internal combustion engine. Since the temperature sensing portion of the second valve is provided independently of the first valve in the fuel passage upstream of the second valve portion, the inertial mass of the movable portion of the first valve due to the addition of the second valve is reduced. The response does not deteriorate due to the increase of the inertia mass of the movable portion of the second valve, and the response does not deteriorate. It is possible to quickly respond to a temperature change, and since the temperature sensing portion of the second valve is provided in the fuel passage on the upstream side of the second valve portion of the second valve, the second valve portion can be opened and closed. Regardless, it has the effect of being able to quickly respond to changes in the temperature of the fuel flowing into the fuel passage. It is possible.

In particular, according to the present invention, the fuel temperature responsiveness of the second valve is improved by separating the first valve and the second valve, and the temperature sensing portion of the second valve is connected to the fuel upstream of the second valve portion. Due to the synergistic effect with the improvement of the fuel temperature responsiveness of the second valve due to the arrangement in the passage, it is possible to quickly react to the rise in the fuel temperature and prevent the fuel from being vaporized.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of the pressure control device of the present invention. FIG. 2 is a sectional view taken along the line BB 'in FIG. FIG. 3 is a sectional view taken along the line AA 'in FIG. 1 ... first valve 2 ... second valve 3 ... housing 22 ... thermowax (thermosensitive part)

Claims (3)

(57) [Claims] 1. An inflow port for inflow of fuel, an outflow port for outflow of fuel, a fuel passage communicating between the inflow port and the outflow port, and an intake pipe negative pressure of the internal combustion engine provided in the fuel passage. A fuel pressure control device, comprising: a first valve having a first valve portion that controls a fuel supply pressure according to a differential pressure; and a second valve that controls the fuel supply pressure according to a fuel temperature. A second valve portion provided in the fuel passage so as to be independent and in series with the first valve to control a fuel supply pressure; and between the second valve portion and the inflow port. A temperature sensing portion which is provided independently of the first valve in the fuel passage and mechanically biases the second valve portion to increase the fuel supply pressure when the fuel temperature becomes high. A fuel pressure control device, comprising: 2. The fuel pressure control device according to claim 1, wherein the second valve portion of the second valve is provided downstream of the first valve. 3. The fuel pressure control device according to claim 1, wherein the temperature sensing portion of the second valve is provided upstream of the first valve.