JP2924466B2 - Diaphragm pump - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a diaphragm pump, and more particularly to a diaphragm pump driven by reciprocating a plunger to displace a diaphragm through a working fluid.

[0002]

2. Description of the Related Art A pump chamber and a working fluid chamber defined by a diaphragm are provided, and a plunger is inserted into a cylinder communicating with the working fluid chamber, and the plunger reciprocates, so that a pressure change in the working fluid chamber is reduced. A diaphragm pump has been filed in which a diaphragm pulsates based on this, and a liquid supplied into the pump chamber is discharged from the pump chamber to perform a pumping action. (Japanese Utility Model Application No. 4-122235)

In this diaphragm pump, when the plunger is located at the bottom dead center, the diaphragm is also set at a predetermined lower position, and when the plunger is located at the top dead center, the diaphragm is also set at a predetermined upper position. In addition, a stopper having a communication hole is provided to regulate the maximum displacement of the diaphragm.

[0004]

In such a diaphragm pump, when the viscosity of the working fluid becomes high at low temperature, when the plunger descends, the working fluid between the diaphragm and the protection plate passes through the communication hole of the protection plate to the cylinder. The return is delayed, and even if the plunger is located at the bottom dead center, the diaphragm does not return to the predetermined position and the inside of the cylinder communicates with the working fluid storage chamber, so that the working fluid is supplied from the working fluid storage chamber into the cylinder. Will be. Thereafter, if the plunger rises without returning the diaphragm to the predetermined position, the diaphragm tends to be displaced more than the position of the stopper which restricts the diaphragm within the predetermined range, and the diaphragm may be subjected to concentrated stress in the communicating hole of the stopper. Occurs. SUMMARY OF THE INVENTION It is an object of the present invention to improve return of hydraulic fluid from a hydraulic fluid chamber into a cylinder even at a low temperature, and to prevent damage to a diaphragm.

[0005]

According to the present invention, there is provided a pump chamber and a hydraulic chamber defined by a diaphragm , wherein the hydraulic chamber is a plunger.
Is inserted and communicates with the cylinder filled with hydraulic fluid.
The plunger reciprocates in the cylinder and
Supply and discharge the working fluid to the working fluid chamber and pressurize the working fluid chamber.
By controlling the force, the diaphragm is displaced.
To discharge the liquid supplied to the pump chamber from the pump chamber.
Unishi, the displacement of da Iyafuramu was restricted to a predetermined range, or
When the pressure of the hydraulic fluid chamber decreases, the diamond
Place the stopper against which one side of the flam abuts on the working fluid chamber side.
In Da Iyafuramu pump provided in the low temperature at the
Scan stopper and a heating means for heating the working fluid between said da Iyafuramu faces the said hydraulic fluid chamber, and wherein the stopper
It is set only so as to be flush with.

[0006]

The temperature of the working fluid is raised and the viscosity of the working fluid is lowered by operating a heating means for heating the working fluid between the stopper and the diaphragm at low temperature. For this reason, the return of the working fluid from the working fluid chamber into the cylinder is improved as the plunger is lowered . Also, the stopper and the heating means are flush
Plunger moves away from hydraulic fluid chamber
Direction, move between the diaphragm and the stopper.
The working fluid remaining in the
Intensive and reliable heating of the hydraulic fluid.
it can.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG.
This is a diaphragm type fuel injection pump for supplying fuel to a fuel injection valve 3 for directly injecting fuel into the inside. The diaphragm type fuel pump 1 includes a pump housing 4 and a housing cover 5 fixed to an upper part of the pump housing 4. A working fluid storage chamber 6 is formed in the pump housing 4, and a camshaft 8 having a cam 7 formed therein is disposed in the working fluid storage chamber 6. The camshaft 8 is driven to rotate synchronously by the crankshaft of the engine.

A pump chamber 11 and a working fluid chamber 12 are defined by a diaphragm 10 between the top of the pump housing 4 and the bottom of the housing cover 5 . Top of the bottom Oyobipo pump housing 4 of the housing cover 5 forming a this pump chamber 11 and the hydraulic fluid chamber 1 2, 2
As shown, constitute a stopper 17 for limiting the varying <br/> position in the thickness direction of their respective Daiyafura arm 10 within a predetermined range. A stopper 18 on the side of the hydraulic fluid chamber 12 is formed.
On top of the pump housing 4 are, the stopper 18 and the surface
It is one, and the heating means (heater) 30, which generates heat by energizing when engine coolant temperature cold. The pump housing 4 is formed a cylinder 13 which communicates with the hydraulic fluid chamber 12, the plunger 14 in the cylinder 13 is slidably inserted into the lower end of the plunger 14 abuts against the outer circumferential surface of the cam 7 I have.

A port 15 is formed on the inner peripheral side surface of the cylinder 13, and the port 15 communicates with the working fluid reservoir 6 via a working fluid passage 16. The port 15 opens into the cylinder 13 when the plunger 14 is at the bottom dead center, and is closed when the plunger 14 rises slightly from the bottom dead center. The hydraulic fluid chamber 6, the hydraulic fluid chamber 12, the cylinder 13, and the hydraulic fluid passage 16 are filled with oil, and the hydraulic pressure in the hydraulic fluid chamber 6 is maintained at substantially the atmospheric pressure.

A fuel inflow port 19 is provided above the pump chamber 11.
Is formed. The fuel inflow port 19 is provided with a discharge amount control valve 20 that opens and closes the fuel inflow port 19.
The discharge amount control valve 20 is constantly urged downward by a spring 35. When the solenoid 36 is turned on, the discharge amount control valve 20 is displaced upward against the spring force of the spring 35, and the fuel inflow port is closed. The valve is closed.

The fuel inlet port 19 is provided with a fuel supply pipe 21.
Is connected to the fuel tank 22 via the In the middle of the fuel supply pipe 21, the feed pump 2
3, a filter 24 and a pressure regulator 25 are arranged. The pressure regulator 25 is connected to the return passage 2
7 and is connected to the fuel tank 22. As a result, pressurized fuel adjusted to a substantially constant pressure set in advance by the pressure regulator 25 is supplied to the diaphragm type fuel pump 1. The pump chamber 11 is connected to the fuel injection valve 3 via a fuel discharge passage 28, and a check valve 29 is disposed in the fuel discharge passage.

Next, the operation of the diaphragm pump 1 will be described. When the plunger 14 is located at the bottom dead center, the inside of the cylinder 13 and the working fluid reservoir 6 are connected to the working fluid passage 1.
6. It communicates via port 15. Plunger 14
Begins to rise from bottom dead center and port 15 is fully closed,
Daiyafura arm 10 begins to displace upward from contact with the lower end position the stopper 18. Since the discharge rate system valve 20 is opened, fuel in the pump chamber 11 flows back through the fuel inlet port 19 to the fuel supply pipe 21. Then, the discharge rate system valve 20 when the solenoid 36 is turned on because it is closed, the fuel in the pump chamber 11 starts pressurization. The solenoid 36 is turned on for a time corresponding to the engine operating state, and is turned off when the plunger 14 is located at the top dead center.

As the plunger 14 rises, the pump chamber 1
When the fuel pressure in 1 rises above the opening pressure of the check valve 29, the check valve 29 opens and fuel is supplied to the fuel injection valve 3. The fuel supply amount of the fuel pump 1 is controlled by the closing timing of the discharge flow control valve 20, and the discharge flow control valve 2
The zero valve closing timing is controlled so that the fuel pressure becomes the target pressure.

When the plunger 14 starts descending from the top dead center, the hydraulic pressure in the hydraulic fluid chamber 12 decreases, whereby the diaphragm 10 is displaced downward, and the fuel pressure in the pump chamber 11 also decreases. The valve closing force generated by the fuel pressure in the pump chamber 11 urges the discharge flow control valve 20 upward, the supply fuel pressure adjusted by the pressure regulator 25 and the spring 35 act on the discharge flow control valve 20. When the valve opening force becomes smaller than the valve opening force generated by urging downward, the discharge flow control valve 20 is opened, and fuel flows into the pump chamber 11 from the fuel inflow port. While balancing the fuel pressure in the pump chamber 11 and the hydraulic pressure in the hydraulic fluid chamber 12,
As the plunger 14 moves down, the diaphragm 10 is displaced downward.

[0015] Therefore, for example, by detecting the engine coolant temperature by operating the heating means (heater) 30 provided in the hydraulic fluid chamber 12 at a low temperature engine coolant temperature, the Daiyafura arm 10 and the port <br/> Npuhaujin grayed 4 By raising the temperature of the working fluid during the period , the viscosity of the working fluid is reduced. This ensures that the work
The hydraulic fluid is supplied from the hydraulic fluid chamber 12 through the cylinder 13 to the hydraulic fluid reservoir.
When returning to the chamber 6, the work Doeki return is better, plunger
14 can be prevented from work dynamic fluid remaining in the hydraulic fluid chamber 12 when located at the bottom dead center, Daiyafura arm 10 returns to the predetermined <br/> position location (contact position with the stopper 18) be able to. Therefore, the plunger 14 toward the top dead center moves
When the pressure in the hydraulic fluid chamber 12 rises.
The diaphragm 10 is strong against the housing cover 5
Local stress concentrates on diaphragm 10 by being pressed
Can be avoided .

[0016] FIG. 3 shows a routine for controlling the heating hands stage 30. This routine is executed by interruption every predetermined time. Referring to FIG. 3 , in step 50, it is determined whether or not engine water temperature THW is lower than predetermined temperature TMIN. If THW <TMIN is energized heating hands stage 30 proceeds to step 51. THW ≧ TMI
If N proceeds to step 52 to prohibit the conduction of heat hand stage 30.

Although the heating is performed by detecting the engine water temperature, the temperature of the working fluid may be directly detected without being limited to the engine water temperature.

[0018]

According to the present invention, together because that was also better fluidity of the hydraulic fluid in the cold, the decrease in pressure of the working fluid chamber
When returning the hydraulic fluid to the cylinder
improves. Therefore, the plunger is located at the bottom dead center
In this state, the diaphragm comes into
While the plunger moves toward the top dead center
When the pressure in the dynamic liquid chamber rises, can Da Iyafuramu is prevented from being damaged by excessive displacement.

[Brief description of the drawings]

FIG. 1 is an overall view of a diaphragm pump according to the present embodiment.

FIG. 2 is a side sectional view of a part of the diaphragm pump.

FIG. 3 is a flowchart for executing control of a heating unit.

[Explanation of symbols]

 1 ... Diaphragm type fuel pump 10 ... Diaphragm 11 ... Pump chamber 12 ... Hydraulic fluid chamber 14 ... Plunger 17,18 ... Stopper 30 ... .... Heating means

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Masahiko Masuchi 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation (72) Inventor Akihiro Yamanaka 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation ( 56) References JP-A-62-178785 (JP, A) JP-A-61-132784 (JP, A) JP-A-62-150513 (JP, U) JP-A-39-34943 (JP, Y1) (58) ) Surveyed field (Int.Cl. ⁶ , DB name) F04B 43/067 F02M 37/06

Claims (1)

(57) [Claims] A pump chamber defined by a diaphragm and a hydraulic fluid chamber, wherein the hydraulic fluid chamber is connected to a cylinder into which a plunger is inserted and filled with hydraulic fluid, and the plunger reciprocates in the cylinder. said hydraulic fluid to exercise
Supply and discharge hydraulic fluid to the chamber to control the pressure in the hydraulic fluid chamber
By, by displacing the previous SL diaphragm so as to discharge the liquid supplied to the pump chamber from the pump chamber,
Limits the displacement of the diaphragm in a predetermined range, and wherein the operation
As the pressure in the fluid chamber drops, one of the diaphragms
: In this diaphragm-type pump in which the surface is provided abutting stopper to the work dynamic liquid chamber side of, the heating means for heating the working fluid between said stopper and said diaphragm at low temperatures, faces the said hydraulic fluid chamber, and ,
Diaphragm pump, characterized in that the set only to be the stopper flush.