JPS614858A - Electronic type fuel injection pump - Google Patents

Abstract

PURPOSE:To permit a control unit to be incorporated into a pump body with simple and inexpensive constitution by housing the control unit into a heat insulating case installed onto a pump body for the control of fuel injection and installing a heat liberating means onto the heat shielding case. CONSTITUTION:As for the captioned pump 1, a control sleeve 3 as fuel adjusting member is fitted onto a plunger 2, and saud sleeve 3 is connected to an electrically driven actuator 5 through a rod 4. In this case, a control unit 6 for drive-controlling the actuator 5 is housed into a heat shielding case 9 installed onto the casing 8 of a pump body 7. The heat shielding case 9 is constituted of a box body 10 having a heat insulating layer 15 and a heat insulating cover 11 for closing the upper opening of the box body 10, and a ventilating pipe 21 for linerating the hot air in the box body 10 is installed onto the heat shielding cover 11. The control unit 6 is installed onto the bottom surface of an inner wall body 13 forming the box body 10 by screws through a spacer 16.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an electronic fuel injection pump in which a control electronic circuit for the fuel injection pump is incorporated into the pump body.

BACKGROUND ART Electronic fuel injection pumps generally include an electric actuator for adjusting fuel injection amount, fuel injection timing, etc., and a control unit for driving and controlling the actuator. The control unit is separate from the fuel injection pump body and installed in a location away from the engine to remove dust and heat from the engine.
The actuator and the actuator are connected in an airtight manner by a wire harness. By the way, with such a configuration, if you try to ensure compatibility by replacing the control unit and the fuel injection pump body as units, the control unit and the fuel injection pump body, which are replacement units, may not meet the required standard values. Furthermore, after replacement, readjustment is required, which requires extra effort and increases the price.

Therefore, the present applicant formed a cooling chamber for accommodating the control unit in the casing of the fuel injection pump, configured the fuel in the fuel tank to be guided into the cooling chamber as a cooling medium, and thereby The control unit is built into the fuel injection pump without the influence of high temperatures generated by the engine, and the assembly and
1. Fuel injection port that significantly reduces the man-hours required for adjustments, inspections, etc. He proposed a
Publication No. 3256).

Problems to be Solved by the Invention However, in this proposed device, the control unit is immersed in fuel in the cooling chamber, so the control unit is housed in an oil-tight case, and the fuel does not directly adhere to electronic components, etc. However, in this respect, the configuration of the control unit becomes complicated and the cost also increases.

Therefore, it is an object of the present invention to provide an electronic fuel injection pump in which the control unit is incorporated into the fuel injection pump body without the need for placing it in an oil-tight case, and which is not affected by the heat generated by the internal combustion engine. It is about providing.

Structure of the Invention The structure of the present invention is an electronic fuel injection pump in which fuel injection is controlled according to an electric signal from a control unit, and the control unit is housed in a heat insulating case provided in the fuel injection pump body, and It is characterized by the provision of a heat dissipation means for discharging the heat inside the heat insulating case to the outside of the heat insulating case.

Since the operation control unit is housed in a heat insulating case provided on the fuel injection pump body, it is possible to integrate the fuel injection pump body and the control unit, and the heat generated from internal combustion engine installation can be removed. Heat shielded by an insulated case,
Effectively prevent the control unit from being exposed to high heat. In addition, a heat dissipation means is provided to release the heat inside the heat insulating case to the outside, so the heat emitted from the control unit itself is released outside the heat insulating case by this heat dissipation means, making it possible to integrate the control unit with the fuel injection pump. Nevertheless, the control unit can be operated within a specified operating temperature range without being affected by the high heat of the engine.

Embodiment FIG. 1 shows an embodiment of an electronic fuel injection pump according to the present invention. In the electronic fuel injection pump 1, a control sleeve 3 as a fuel adjustment member is fitted into a gland 2, and the control sleeve 3 is connected to an electric actuator 5 via a rod 4.

The actuator 5 is driven in accordance with a control signal from a control unit, which will be described later, and thereby controls the position of the control sleeve 3 so that a fuel injection amount according to predetermined governor characteristics is obtained. Since the control mechanism itself for electronically controlling the fuel injection amount between the control sleeve 3 and the actuator 5 is well known, detailed illustration thereof will be omitted here.

A control unit 6 comprising a control circuit for driving and controlling the actuator 5 is housed in a heat insulating case 9 provided in the casing 8 of the injection pump main body 70.

The structure of the heat insulating case 9 will be explained with reference to FIGS. 1 and 2. The heat insulating case 9 has a double wall structure with one end open and the peripheral wall and bottom wall each supporting a heat insulating layer. It consists of a box 10 with a shape of 9, and a heat insulating lid 11 for closing the opening of the box 10. In the illustrated embodiment, the box lO has an outer wall 12 whose bottom wall 12a is integrated with the casing 8, and the bottom of the outer wall 12 has a cylindrical shape for supporting the inner wall 13. A plurality of pedestals 14 are integrally formed with the outer wall body 12. The inner wall body 13 is placed on these pedestals 14 and firmly screwed onto these pedestals 14. Therefore, the inner wall 13 is fixed within the outer wall 12 at a predetermined distance from the outer wall 12, thereby forming the υ22 double wall structure box 10.

In order to further improve the heat insulation properties of the box body 10, the outer wall body 1
A heat insulating layer 15 filled with an appropriate heat insulating material is formed between the heat insulating layer 2 and the inner wall body 13.

The heat insulating lid 11 has an inner wall 1 on the back surface of a metal plate member 11a.
A plate-shaped heat insulating material 11b having a shape corresponding to the shape of the opening 3 is attached, and the plate member 11tL is configured to be screwed to the four corners of the outer wall body 12.

The control unit 6 includes a spacer 16 on the bottom surface of the inner wall body 13.
This allows the control unit 6 to be securely fixed within the heat insulating case 9 at a predetermined distance from the bottom surface of the inner wall 13. Note that a plurality of positioning protrusions 17 are provided inside the peripheral wall of the outer wall 12, and these protrusions 17 allow the inner wall 13 to be positioned within the outer wall 12. It is configured to be positioned at a predetermined position within the outer wall body 12 and to facilitate assembly.

A wire harness 18 from the control unit 6 is connected to the inner wall body 1
3 through a through hole 19 drilled in the outer wall body 12, it is inserted into a wire harness drawer cylinder 20 formed integrally with the outer wall body 12, and is drawn out to the outside of the heat insulating case 9 via the cylinder body 20. .

The inner open end 20a of the cylinder 20 is in close contact with the inner wall 13, and if necessary, the inner open end 20a and the inner wall 13 are in close contact with each other.
The outer wall 1 is bonded with adhesive to create an airtight state.
The heat insulating space formed between 2 and the inner wall 13 can be configured so as not to communicate with the inside of the inner wall 13.

After the wire harness 18 is inserted into the inside of the cylindrical body 20, an appropriate sealing resin is filled, thereby fixing the wire harness 18 to the heat insulating case 9 and sealing the cylindrical body 20.

In order to prevent the temperature inside the heat insulating case 9 from rising due to heat generation in the control unit 6, the heat insulating lid 11 is provided with a ventilation pipe 21 for discharging hot air within the inner wall body 13. In addition, the heat inside the heat insulating case 9 that is generated when the control unit 6 is energized can be released to the outside, and the temperature rise inside the heat insulating case 9 can be suppressed.

According to such a configuration, since the control unit 6 is integrated with the fuel injection pump body 7, handling is convenient, and the wiring connecting between the control unit 6 and the fuel injection pump body 7 can be easily drawn. Since there is no need to rotate the injection pump and there is no need to consider compatibility between the injection pump and the control unit, the number of man-hours for adjustment is significantly reduced, and costs can be reduced.

The heat insulating case 9 can protect the control unit 6 from the heat from the engine, and the ventilation pipe 21 can take care of the self-heating of the control unit 6. , overheating due to energization of the control unit 6 is not caused.

In addition, with this configuration, it is only necessary to provide an insulating case in the non-operating case of the fuel injection pump, so the structure is significantly simpler than when the control unit is cooled by fuel, and it can also be applied to existing fuel injection pumps. It has the advantage of being extremely easy to use and low cost. still,
In the above, a part of the outer wall 12 is integrated with the casing 8, but it goes without saying that the outer wall 12e may be made separate from the casing 8.

Further, in the above embodiment, a case is shown in which the heat insulating space formed between the inner wall body 13 and the outer wall body 12 is filled with an appropriate heat insulating material, but the inside of the heat insulating space may be made into an air layer or a vacuum The heat insulating means is not limited.

Furthermore, the present invention is applicable not only to distribution type electronic fuel injection pumps but also to all types of electronic fuel injection yJe engines.

Effects of the Invention According to the present invention, as described above, the structure is simpler than that of the conventional one, it can be easily applied to existing fuel injection pumps, and it effectively blocks heat from the engine. This provides an excellent effect of integrating the fuel injection pump main body and the control unit.

[Brief explanation of the drawing]

FIG. 1 is a partially sectional front view showing an embodiment of the present invention;
FIG. 2 is a plan view of the box 10 shown in FIG. 1. l... Electronic fuel injection pump, 5... Actuator, 6... Control unit, 7... Fuel injection pump body, 8... Casing, 9... Heat insulation case, 10...
・Box body, 11... Insulation lid, 21... Ventilation nozzle.

Claims (1)

[Claims] 1. In an electronic fuel injection pump in which fuel injection is controlled according to an electrical signal from a control unit, the control unit is housed in a heat insulating case provided in the fuel injection pump body, and the heat in the heat insulating case is transferred to the heat insulating case. An electronic fuel injection pump characterized by being provided with a heat dissipation means for discharging heat to the outside of the case.