JPH05306662A - Fuel heating device - Google Patents

Abstract

PURPOSE:To secure the reliability of a device by preventing the generation of a damage gap caused by cracking in a resin case body or creeping deformation, and improving nonconformity by the entry of water or fuel vapor into an inner part. CONSTITUTION:A metal body main body 2, a PTC heat generation body 7, and a resin case body 13 covering these are provided. Electrode terminals 4, 6 electrically connected to the PTC heat generation body 7 are provided, and the PTC heat generation body 7 is assembled around a center part of the body main body 2. The body main body 2 and the case body 13 are assembled contactlessly by O-rings 26, 27 provided at both end side parts of the PTC heat generation body 7 in the body main body 2, and an electric circuit part including the PTC heat generation body 7 is sealed by the O-rings 26, 27.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel heating device, and more particularly to a fuel heating device for heating atomized fuel injected from an injector in an engine equipped with an electronically controlled fuel injection device in order to atomize the atomized fuel. Regarding the device.

[0002]

2. Description of the Related Art Conventionally, as a fuel heating device of this type,
For example, there is Japanese Patent Application No. 3-122778. This conventional device includes a metal body having a nozzle hole through which atomized fuel injected by an injector passes, a PTC heating element for heating the atomized fuel passing through the nozzle hole, and a resin covering the PTC heating element and the body. A cover body (corresponding to a case body in the present invention). And the cover body is
It is insert-molded into the body of the PTC heating element and accessories.

[0003]

SUMMARY OF THE INVENTION In the above-mentioned conventional apparatus, due to the difference in thermal expansion between the resin cover body and the metal parts such as the body body and accessory parts insert-molded therein,
The cover body is cracked and creep-deformed, so that a clearance (hereinafter referred to as a damage clearance) that impairs the airtightness of the inside is generated. Then, the infiltration of water from the damaged clearance may cause a malfunction due to the short circuit of the electrodes in the electric circuit of the PTC heating element, and the invasion of the fuel vapor may cause the heating of the PTC heating element due to the reduction of the PTC heating element. This causes a problem such as deterioration in performance, and eventually reduces the reliability of the device.

Therefore, the present invention has been made to solve the above-mentioned problems, and the purpose thereof is to prevent the generation of a damage clearance due to cracking and creep deformation of a resin case body, and to prevent moisture and fuel inside. It is an object of the present invention to provide a fuel heating device capable of ensuring the reliability of the device by improving problems caused by the infiltration of steam.

[0005]

SUMMARY OF THE INVENTION A fuel heating apparatus of the present invention for solving the above-mentioned problems is a metal body main body having a nozzle hole through which atomized fuel injected by an injector passes, and atomized fuel passing through the nozzle hole. PTC heating element for heating
C heating body and a resin case body that covers the body body, and an electrode terminal electrically connected to the PTC heating body, and a PTC around the central portion of the body body.
A heating element is assembled, the body body and the case body are assembled in a non-contact state by a rubber O-ring interposed between the body main body and the case body at portions on both end sides of the PTC heating element, and The O-ring seals the electric circuit section including the PTC heating element.

[0006]

According to the above means, the case body and the body body are held in a non-contact state by the O-ring interposed between the resin case body and the metal body body, and the PTC heat generating body is included. The electric circuit is sealed.
Therefore, the cracking of the case body due to the difference in thermal expansion between the case body and the body body is avoided, and the creeping deformation of the case body causes the O-ring to follow and deform, thereby improving the sealing property of the electric circuit portion including the PTC heating element. Secured.

[0007]

An embodiment of the present invention will be described with reference to the drawings. In this example, the fuel heating device is applied to a heated air assist type injector, and the fuel heating device is shown in a sectional view in FIG. The case body 13 having a substantially cylindrical shape is cast-molded with a resin having excellent heat insulation and has a space portion 16 therein. In this case body 13,
A minus electrode terminal 4 forming an electric circuit of a PTC heating element 7 described later, a plus electrode terminal 6, and a cylindrical conducting collar 9 conducting to the electrode terminal 6.
And a ring-shaped insulating snap 18 that insulates the exposed portions of the annular portions of the two electrode terminals 4 and 6 are insert-molded. The inner peripheral portions of the annular portions of both electrode terminals 4, 6 and the inner peripheral surface of the collar 9 and the inner peripheral surface of the insulating snap 18 are exposed in the space 16 of the case body 13. The annular portions of the two electrode terminals 4, 6, the collar 9 and the insulating snap 18 are formed so that their inner diameters are substantially equal to each other, and they are arranged on the same axis as the space portion 16.

Further, the case body 13 has a bottomed cylindrical air control valve insertion portion 13D formed in parallel with the space portion 16 at an upper portion thereof, and a side opening corner formed below the insertion portion 13D. It has a cylindrical connector insertion portion 13F. The connector insertion portion 13F projects the connection end portions of the two electrode terminals 4 and 6, and the air control valve insertion portion 13D communicates with the space portion 16 of the case body 13 through the communication hole 13.
It is connected by B.

The substantially cylindrical body body 2 which is inserted into the space 16 of the case body 13 is made of an aluminum alloy or the like having excellent thermal conductivity. The body body 2 has a hollow portion as a nozzle hole 2D. The rivet 12 is press-fitted into the opening end of the nozzle hole 2D and fixed by caulking at the end 2E at the tip (lower end) of the body 2 and a plurality of injection holes 2 communicating with the nozzle hole 2D.
G is radially formed by punching. A flange portion 2H is formed at an upper end portion of the body body 2, and a rubber O-ring 26 having excellent sealing property is fitted in a ring groove (reference numeral omitted) on the outer periphery of the flange portion 2H. The flange portion 2H abuts on the upper surface of the exposed portion of the negative electrode terminal 4 and is electrically connected thereto. Further, a concave portion 2B for fitting an adapter 25 of an injector 21 described later is formed on the upper end surface of the body body 2.

The lower end of the body 2 is a case body 13.
A metal fixing ring 28 is press-fitted into the tip of the metal fixing ring 28 via a rubber O-ring 27 having excellent sealing properties. As a result, the body 2 and the case body 13
Has been fixed. Further, the upper and lower O-rings 27 and 28 arranged at the upper and lower ends of the body 2 serve as a seal function at the relevant portions of the body 2 and the case body 13, and the body 2 and the case body 13 are not sealed. Holds in contact.

The description will be continued with reference to FIG. 2 which is a sectional view taken along line AA of FIG. 1 in addition to FIG. Both O of the body 2
An adhesive surface 2C having a width across flats is formed on the outer peripheral surface between the rings 27 and 28. A strip-plate-shaped PTC heating element 7 is adhered to each adhesive surface 2C with a conductive adhesive. The PTC heating element 7 is called a PTC thermistor or a sheet heating element, and as is well known, it has an immediate heating property, has a characteristic that it rises to a set temperature in a short time, and it stabilizes at a constant temperature by self-controlling property. ing.

Further, a pair of insulating supports 5 which are in surface contact with the adhering surfaces 2C on the outer peripheral surface of the body 2 and have flanges at the upper and lower ends thereof are attached to the respective arcuate surfaces. .. The flange of the insulating support 5 is formed to have an outer diameter slightly smaller than the inner diameters of the annular portions of the electrode terminals 4 and 6, the collar 9 and the insulating snap 18. The two PTC heating elements 7
Are clamped by a leaf spring 8 made of a conductive material and having a substantially C-shaped cross section. The curved portion of the leaf spring 8 surrounds the one insulating support 5, and its outer peripheral surface contacts the inner peripheral surface of the collar 9 and is electrically connected thereto.

The procedure for assembling the fuel heating device will be described with reference to the exploded explanatory view of FIG. The PTC heating element 7 and the accessory parts (insulation support 5 and leaf spring 8) attached to the PTC heating element 7 are assembled to the body 2 in advance, and the upper O
Install the ring 26. On the other hand, the negative electrode terminal 4, the positive electrode terminal 6, the collar 9 and the insulating snap 18 are integrally formed on the case body 13 by insert molding.

Then, the body body 2 in which the PTC heating element 7 and the accessory parts attached thereto are assembled is inserted into the space 16 of the case body 13. As a result, the body body 2 is electrically connected when the flange portion 2H of the body body 2 contacts the negative electrode terminal 4 of the case body 13 to form a negative electrode. Further, the leaf spring 8 is brought into conduction by elastically contacting the collar 9 of the case body 13 to form a positive electrode. Also, the upper O-ring 26 attached to the body 2
Is compressed by using the inner wall of the space portion 16 of the case body 13 as a seal portion and seals the fitting portion. Then, the fixing ring 28 is press-fitted into the front end portion of the body 2 protruding from the case body 13 via the lower O-ring 27. As a result, the O-ring 27 is compressed using the inner walls of the case body 13, the body 2 and the fixing ring 28 as a seal portion, and seals the joint portion. Also, the lower O
The body 27 and the case body 13 are held in non-contact with each other by the ring 27 and the O-ring 26 on the upper portion, and the electric circuit portion including the PTC heating element 7 is sealed.

Next, the structure for installing the fuel heating device in the engine body will be described. As shown in FIG. 1, the case body 13 is the intake manifold portion 3 of the engine body.
It is fitted into the mounting hole 2 through a mounting seal ring 24. In addition, the tip of the injector 21 is fitted in the upper portion of the space 16 of the case body 13 via an injector O-ring 22 arranged in a ring groove (reference numeral omitted) of the inner wall of the case 21, and an adapter for the injector 21. Two
5 is fitted into the recess 2B of the body 2 via the adapter seal 23. Further, the tip of the air control valve 40 is fitted into the air control valve insertion portion 13D of the case body 13 via the seal ring 42. The mounting seal ring 24,
The injector O-ring 22, the adapter seal 23, and the control-valve seal ring 42 are all compressed at the relevant portions as a seal portion to perform a sealing function.

As is well known, the valve of the injector 21 is opened by the action of the magnetic force generated by energizing the solenoid coil, and atomized fuel is injected from the tip of the valve. Further, the adapter 25 has a fuel injection hole 25B communicating with the nozzle hole 2D, and an appropriate number of adapters that open to an air gallery (denoted by reference numeral 15) formed on the outer periphery of the adapter 25 and join the fuel injection hole 25B in an inclined manner. Air assist hole 25
Have A and. The air control valve 40 controls the amount of assist air supplied to the fuel heating device by an air pump (not shown). A power connector (not shown) electrically connected to the electrode terminals 4 and 6 is inserted into the connector insertion portion 13F.

In the fuel heating device, when electricity is applied to the power connector of the fuel heating device, electricity flows from the positive electrode terminal 6 which is the positive electrode through the collar 9 and the leaf spring 8 and through the PTC heating element 7. , An electric circuit flowing through the body 2 which is a negative electrode and the negative electrode terminal 4. Then, the PTC heating element 7 rapidly generates heat by converting electric energy into heat energy, the temperature rises to near the Curie temperature, the body 2 is heated to a high temperature, and is kept at a constant temperature. On the other hand, the air control valve 40
The assist air supplied through the air enters the air gallery 15 through the communication hole 13B of the case body 13, and flows from the air assist hole 25A of the adapter 25 of the injector 21 to the fuel injection hole 25B.

The atomized fuel injected from the injector 21 is atomized by the assist air at the confluence of the fuel injection hole 25B of the adapter 25 and the air assist hole 25A, and is then heated to the high temperature. By colliding with the wall surface of the nozzle hole 2D of the main body 2 and being heated,
Further, while being atomized, some of the components (low boiling point components, etc.) in the fuel are vaporized and injected from the injection hole 2G at the tip into the intake manifold portion 32 of the engine body to be supplied into the engine cylinder. To be done. As a result, improved combustion of the engine can reduce harmful exhaust emissions and improve fuel economy.

According to the above fuel heating device, the case body 13 and the body body 2 are brought into non-contact with each other by the upper and lower O-rings 26 and 27 interposed between the resin case body 13 and the metal body body 2. The electric circuit portion including the PTC heating element 7 is sealed while being held. Therefore, cracking of the case body 13 due to the difference in thermal expansion between the case body 13 and the body body 2 is avoided, and the case body 13 is prevented.
The respective O-rings 26 and 27 are deformed following the creep deformation of (1), whereby the sealing property of the electric circuit portion including the PTC heating element 7 is secured.

Therefore, cracking of the case body 13 due to the difference in thermal expansion between the case body 13 and the body body 2 and generation of damage clearance due to creep deformation are prevented, and the sealing property of the electric circuit portion including the PTC heating element 7 is secured. Because you can
In addition to the malfunction of the injector 21 due to the short circuit of the electrodes due to the infiltration of water in the assist air into the electric circuit section,
The inconvenience such as the deterioration of the heating performance due to the reduction of the PTC heating element 7 caused by the intrusion of the fuel vapor injected from the can be improved, and the reliability of the device can be secured.

Further, since the two PTC heating elements 7 are clamped by the one leaf spring 8, one conventional leaf spring is required for each PTC heating element (Japanese Patent Application No.
Compared to No. 122778), the number of parts is reduced,
Assembly work can be simplified. Further, the collar 9 which receives the spring force of the leaf spring 8 is thinner than the conventional device. As a result, the PTC heating element 7 to the collar 9
Through this, the amount of heat radiation transmitted to the case body 13 can be reduced, and the heating amount of the body 2 can be increased accordingly, and as a result, the heating response can be improved.

[0022]

According to the fuel heating apparatus of the present invention, cracking of the case body due to the difference in thermal expansion between the case body and the body body and damage gap due to creep deformation are prevented, and the PTC is prevented.
Since it is possible to secure the sealing property of the electric circuit part including the heating element, the function is stopped due to the short circuit of the electrode due to the infiltration of water into the electric circuit part, and the reduction of the PTC heating element due to the intrusion of the fuel vapor. It is possible to improve the problems such as deterioration of heating performance due to, and ensure the reliability of the device.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a fuel heating device.

FIG. 2 is a sectional view taken along the line AA of FIG.

FIG. 3 is an exploded view of a fuel heating device.

[Explanation of symbols]

 2 Body main body 4, 6 Electrode terminal 7 PTC heating element 13 Case body 21 Injector 26, 27 O-ring

Claims (1)

[Claims] 1. A metal body having a nozzle hole through which atomized fuel injected by an injector passes, a PTC heating element for heating the atomized fuel passing through the nozzle hole, and a resin covering the PTC heating element and the body body. A case body, an electrode terminal electrically connected to the PTC heat generating body, and a PTC heat generating body assembled around a central portion of the body body, wherein the body body and the case body are the body body. In a non-contact state by a rubber O-ring interposed between the PTC heating elements on both sides of the PTC heating element, and the electric circuit section including the PTC heating element is sealed by the O-rings. Heating device.