JPS63195481A - Pressure regulating valve - Google Patents

Abstract

PURPOSE:To prevent fuel from causing air bubbling by providing, between a spacer and a valve body holder, a back spring and thermo-sensing spring composed of a shape memory alloy that elongates when the temperature exceeds a set point. CONSTITUTION:A back spring 39 is inserted between a spacer 37 engaged to the inner side of a holder 31 and the support 38 for the holder 31. On the outside circumference of a small diameter cylinder 37a, thermo-sending spring 41 composed of a shape memory alloy is inserted between a shoulder portion 37c and the inner edge portion 31b of the holder 31. Thereby, when the temperature exceeds the set point, the fuel pressure is raised and the air bubbling of fuel can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a pressure regulating valve used primarily in a fuel injection device for an internal combustion engine for an automobile.

(Prior Art) Conventionally, in a fuel injection device for an internal combustion engine for an automobile, as shown in FIG. 2, a fuel injection valve 1. Starting fuel injection valve 1a
A pressure TRIIF valve 2 is provided upstream of the fuel pressure TRIIF valve 2 to keep the fuel pressure constant (usually 2.55 N#/aj). 3 is a fuel tank, 4 is a fuel pump, 5 is a fuel damper, 6 is a fuel filter, and 7 is a surge tank. Intake air flows in the direction of the arrow. 8 is a negative pressure passage that introduces the negative pressure of the surge tank 7 into the pressure regulating valve 2; 9 is a fuel passage that communicates between the fuel pump 4 and the fuel injection valve 1° starting fuel injection valve 1a and the pressure regulating valve 2; Reference numeral 10 denotes a fuel return passage for returning surplus fuel to the fuel tank 3.

FIG. 3 shows a longitudinal sectional view of the pressure regulating valve 2. As shown in FIG. Casing 1
A diaphragm 13 is fixed between 1 and 12, and a diaphragm chamber 14 is formed on the casing 11 side, and a fuel chamber 15 is formed on the casing 12 side.

Diaphragm spring 16 within diaphragm chamber 14
is inserted, and the set pressure of the diaphragm spring 16 is 2.55 kg/cti. Casing 11
A negative pressure connecting pipe 17 is attached to the , which communicates with a surge tank 7 (both shown in FIG. 2) via a negative pressure passage 8 . A fuel inlet connecting pipe 18 is attached to the side of the casing 12, and is connected to the fuel injector 1 through the fuel passage 9. It communicates with the starting fuel injection valve 1a and the fuel pump 4 (both shown in FIG. 2). A fuel outlet connecting pipe 19 is provided at the axial center of the casing 12, the inner side of the fuel outlet connecting pipe 19 projects into the fuel chamber 15, and a sheet member 20 is provided at the end. A valve body 21 is attached to the center of the diaphragm 13, and the reciprocating movement of the diaphragm 13 opens and closes the fuel outlet.

With this configuration, the spring force (2.55Kg/
cIi) When the diaphragm 13 is pushed up by the fuel pressure, excess fuel enters the fuel outlet connection pipe 19 and is returned to the fuel tank 3 via the fuel return passage 10. In this case, the diaphragm chamber 1 is
4 has the same pressure as the surge tank 7, so the fuel pressure fluctuates according to the intake negative pressure, so that the relationship between fuel pressure car intake negative pressure - constant (9/ci at 2°55) is maintained. , fuel pressure is always controlled (for example, Japanese Patent Publication No. 49-37049
Publication No.).

However, with low boiling point fuels such as alcohol-containing fuels and low quality fuels that have recently been introduced as fuel for internal combustion engines for automobiles, paper is generated in the fuel when the fuel temperature rises to about 80°C. Further, paper may also occur during operation in which the temperature rises while the fuel flow 1 is small, such as idling operation at high temperature or low speed operation immediately after startup.

Bubbling of fuel at high temperatures can be prevented by increasing the fuel pressure. For example, for the above-mentioned low boiling point fuel, if the fuel humidity is about 80° C., the temperature may be set to 3.5 Ky/d. Therefore, as shown in FIG. 4, the diaphragm spring that elastically biases the diaphragm 13 is
It consists of a main diaphragm spring 22 and an auxiliary diaphragm spring 23 made of a shape memory alloy whose spring characteristics change depending on the ambient temperature. Some devices are equipped with a heater 24 that is variably controlled. 25 is a guide pipe that guides the sub-diaphragm spring 23, and 26 is a harness that supplies electricity to the heater 24. With this configuration, the valve opening setting pressure (fuel pressure) of the valve body 21 is changed according to the operating condition of the internal combustion engine (for example,
1-167155).

(Problem to be solved by the invention) However, the above sub-diaphragm spring:
Since the fuel temperature is not directly sensed and the heat from the heater 24 is transferred to the air, heat transfer loss occurs and responsiveness to pressure control is poor. Further, it requires a fuel temperature sensor, a controller, a heater, etc. to detect the fuel temperature according to the operating state of the internal combustion engine, which complicates the device and is disadvantageous in terms of reliability.

Therefore, this invention has a simple configuration and good responsiveness to pressure control, and when the fuel temperature exceeds a certain value (approximately 80°C), it increases the fuel pressure (for example, 3.5 Ky/cd>) and prevents the fuel from becoming bubbles. The purpose is to provide a pressure regulating valve that can prevent

(Means for Solving the Problems) In order to achieve the above object, the pressure regulating valve of the present invention includes a diaphragm chamber for introducing a reference negative pressure, a fluid chamber for introducing a fluid for adjusting the pressure, and both chambers. a diaphragm that partitions between the fluid chambers, a diaphragm spring that is inserted into the diaphragm chamber and urges the diaphragm toward the fluid chamber, and a valve body that is provided on the diaphragm and opens and closes the fluid outlet of the fluid chamber. A holder attached to a side wall of the fluid chamber is disposed on the outer periphery of the valve body protruding into the fluid chamber, and a protrusion that can engage with the valve body is disposed inside the holder. A spacer is slidably fitted between the holder and the spacer, the spacer is urged toward the diaphragm side, and the protrusion does not interfere with the operation of the valve body when the fluid temperature is below a set fluid temperature. a back spring that holds the spacer in position; and a back spring that biases the spacer in the opposite direction and expands when the fluid temperature is above a set fluid temperature to engage the protrusion with the valve body and move the valve body in the closing direction. A biasing temperature-sensitive spring made of a shape memory alloy is inserted, and a communication hole for introducing fluid around the temperature-sensitive spring is provided in the side wall of the holder.

(Function) With this pressure regulating valve, between low temperature and set temperature,
The temperature-sensing spring is pressed by the back spring and is in a contracted state, and the valve body is only receiving the biasing force of the diaphragm spring.
g/Ci). The fluid temperature rises to the set temperature (
For example, when the temperature rises above 80°C, the temperature-sensitive spring made of a shape memory alloy expands and engages the protrusion of the spacer with the valve body, and together with the diaphragm spring biases the valve body in the valve opening direction, causing the fuel pressure to rise to the second level. 2 set pressure (e.g. 3°5 to 9
/cd>.

(Example) The present invention will be described below based on drawings showing examples. The first factor shows a longitudinal sectional view of a fuel pressure regulating valve of a fuel injection device as an embodiment of the present invention. FIG. 1 shows the normal pressure state. Components that are the same as those in the prior art are given the same numbers as in FIG. 3, and explanations thereof will be omitted. Reference numeral 31 designates a cylindrical holder having seven flange 31a at one end, the peripheral edge of the flange 31a sandwiching the diaphragm 13 together with the annular plate 32, and is fixed to the joint of the casing 11.12 by caulking via the gasket 33.34. ing. 35 is a valve body, and the fuel chamber 15
It has a flange portion 35a that protrudes inward. A caulking portion 35b on the base side of the valve body 35 is inserted into the hole for attaching the diaphragm 13 and the shell 36, and is fixed by caulking.

A spacer 37 is fitted inside the holder 31, and has a shape in which a small diameter cylindrical portion 37a and a large diameter cylindrical portion 37b are joined at shoulders 3 and 7C. The outer circumferential side of the large diameter cylindrical portion 37b is slidably inserted into the inner circumference of the holder 31. On the inner circumferential side of the large diameter cylindrical portion 37b, a back spring 39 is inserted between the shoulder portion 37c and an annular support 38 provided on the inner circumference of the end portion of the holder 31. 4o is a retaining ring of the support 38. A temperature-sensitive spring 41 is inserted between the shoulder portion 37c and the inner edge portion 31b of the holder 31 on the outer periphery of the small diameter cylindrical portion 37a. KA spring spring 41 is made of shape memory alloy. A flange 35 of the valve body 35 is provided on the inner periphery of the upper end of the small diameter cylindrical portion 37a.
A protrusion 37d that can be engaged with a is provided. A communication hole 42 for introducing fuel around the temperature-sensitive spring 41 is provided on the side of the holder 31 surrounding the small-diameter cylindrical portion 37a.

In this embodiment, the set pressure of the fuel is set at 2.55 Kg/d by the diaphragm spring 16 at room temperature below that level, based on the fuel temperature of 80°C, which temporarily rises when the car is stopped after continuous operation. is set to . In order to prevent the fuel from becoming bubbles at higher temperatures, the diaphragm spring 16 and temperature-sensitive spring 41 set the temperature to 3.5 kg/d.

The operation of the pressure regulating valve configured as above will be explained.

Fuel pumped from the fuel pump 4 (FIG. 2) flows into the fuel chamber 15 through the inlet connection pipe 18. The fuel pressure and
Depending on the deviation between the effective pressure-receiving area of the diaphragm 13 that receives the pressure and the biasing force of the diaphragm spring 16, the diaphragm 13 is displaced so as to be balanced (see FIG. 1). This equilibrium state is achieved by the displacement of the diaphragm 13.
It is controlled by the amount of fuel flowing out into the fuel outlet connecting pipe 19 from the gap between the valve body 21 and the seat member 20. The spilled fuel passes through the fuel return passage 1o and enters the fuel tank 3.
It is returned to (Figure 2).

When the fuel temperature rises in this equilibrium state and reaches the set temperature of 80°C or higher, the temperature-sensitive spring 41 made of a shape memory alloy expands due to the austenite transformation, and the back spring 3
9 is compressed, and the projection 37d of the spacer 37 is engaged with the 7 flange 35a of the valve body 35. For this reason, the diaphragm
The sum of the biasing force of the spring 16 and the biasing force of the temperature-sensitive spring 41 acts on the valve body 35, and the set fuel pressure increases to 9/9.
Equilibrium is reached at ci. When the fuel pressure in the fuel chamber 15 increases to a set pressure of 3.5 Ky/cd or more, the diaphragm spring 16 is compressed and the valve body 35 opens. As a result, the equilibrium state of the valve body 35 is again controlled by the amount of fuel flowing out from the gap between the displaced valve body 35 and the seat member 20.

When the fuel temperature falls below 80° C., the temperature-sensitive spring 41 made of a shape memory alloy contracts due to martensitic transformation, and the back spring 39 pushes the spacer 37 back until it comes into contact with the inner edge 31b of the holder 31. As a result, the fuel pressure is the normal set pressure (2.55Kg
/ci).

(Effects of the Invention) As described above, in the present invention, a holder attached to the side wall of the fluid chamber is disposed on the outer periphery of the valve body protruding into the fluid chamber of the pressure regulating valve, and the holder is attached to the inside of the holder. A spacer having a protrusion that can engage with the valve body is slidably fitted, and between the holder and the spacer, the spacer is biased toward the diaphragm, and when the fluid temperature is below a set fluid temperature, the protrusion engages the diaphragm. a back spring that holds the spacer in a position where it does not interfere with the operation of the valve body; and a back spring that biases the spacer to the opposite side and expands when the fluid temperature is higher than a set fluid temperature to engage the protrusion with the valve body and A temperature-sensitive spring made of a shape-memory base metal that biases the valve body in the valve-closing direction is inserted, and a communication hole is provided in the side wall of the holder to introduce fluid around the temperature-sensing spring. ,
When used as a fuel pressure regulating valve for fuel injection systems such as automobiles, when the fuel temperature exceeds a certain value, the temperature-sensing spring directly senses the fuel temperature and immediately increases the fuel pressure.
In the case of XX low fuel flow rate operation during standby, there is an effect of preventing the generation of fuel paper when low boiling point fuel is used.

[Brief explanation of the drawing]

FIG. 1 shows a longitudinal cross-sectional view of a pressure regulating valve of a fuel injection device as an embodiment of the present invention, FIG. 2 shows an overall view of a fuel injection device for an automobile, and FIG. 3 shows a longitudinal cross-sectional view of a conventional pressure regulating valve. 4 are explanatory diagrams showing an improvement of the conventional diaphragm spring. 13...Diaphragm 14...Diaphragm chamber 15...Fuel chamber (fluid chamber) 16...Diaphragm spring 19...Fuel outlet passage (fluid outlet) 31...Holder 35...Valve body 37...Spacer 37d...Protrusion 39...Back spring 41...Temperature-sensing spring 42...Communication hole

Claims (1)

[Claims] A diaphragm chamber that introduces a reference negative pressure, a fluid chamber that introduces a fluid that adjusts pressure, a diaphragm that partitions the two chambers, and a diaphragm that is inserted into the diaphragm chamber and biases the diaphragm toward the fluid chamber. A pressure regulating valve consisting of a diaphragm spring and a valve body provided on the diaphragm to open and close a fluid outlet of the fluid chamber, the outer periphery of the valve body protruding into the fluid chamber having a side wall of the fluid chamber. A holder attached to the diaphragm is disposed, a spacer having a protrusion that can be engaged with the valve body is slidably fitted inside the holder, and the spacer is attached to the diaphragm between the holder and the spacer. bias to the side,
a back spring that holds the spacer in a position where the protrusion does not interfere with the operation of the valve body when the fluid temperature is below a set fluid temperature; A temperature-sensitive spring made of a shape memory alloy is inserted into the side wall of the holder to engage the valve body and urge the valve body in the valve-closing direction, and a fluid is introduced into the side wall of the holder around the temperature-sensitive spring. A pressure regulating valve characterized by being provided with a communication hole.