JP2855894B2 - Rocker cover protection device made of synthetic resin - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a protection device for a rocker cover made of synthetic resin provided at the upper end of a cylinder head of an internal combustion engine.

[0002]

2. Description of the Related Art As is well known, in an internal combustion engine of an automobile, there is a demand for not only higher performance and higher output, but also lighter weight of a vehicle. Cylinder blocks and cylinder heads are made of cast iron. In addition to aluminum alloy, rocker covers made of synthetic resin have been put to practical use.

[0003]

However, while the rocker cover made of synthetic resin sufficiently satisfies the demand for weight reduction, it generally has low heat resistance. Therefore, for example, when the engine is continuously operated at a high speed and a high load, the vicinity of the upper deck of the cylinder head is heated to 250 ° C. to 3 ° C. by the heat of combustion.
Becomes high heat to 00 ° C., there is a possibility that the rocker cover would gradually heat deformation from the lower end reaches the melting point. As a result, decrease the holding force of the seal member between the rocker cover and the cylinder head, the sealing performance is low down.

Therefore, it is conceivable to change the material of the synthetic resin to a material having a high melting point, that is, a material having a high heat resistance. However, a material having a high heat resistance requires a large increase in cost.

As a measure for preventing overheating, there is a method in which the temperature of the engine cooling water is detected and the fuel supply is stopped when the temperature of the cooling water is equal to or higher than a predetermined value (see Japanese Utility Model Application Laid-Open No. 57-75133). There is no cover protection measure that shuts off the fuel supply.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and has a rocker cover made of synthetic resin provided at an upper end portion of a cylinder head and a temperature of engine cooling water. An internal combustion engine comprising: a water temperature sensor that detects a temperature of the engine, and a controller that controls a fuel supply amount of the engine according to an operating state detected based on output signals from the water temperature sensor and other sensors. The controller is provided with a control circuit for stopping the fuel supply to the engine when the temperature of the engine cooling water is close to the melting point of the rocker cover transferred from the cylinder head.

[0007]

According to the present invention having the above structure, the temperature of the synthetic resin rocker cover is not directly detected, but is detected by replacing the temperature with the engine cooling water temperature. The controller detects that the engine coolant temperature has been reached from the engine coolant temperature and inputs the signal, and stops the fuel supply (fuel cut) via the control circuit. Therefore, the combustion temperature drops, high heat transfer from the cylinder head to the rocker cover is suppressed, the thermal deformation of the rocker cover can be prevented.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 shows a gasoline engine provided with an electronically controlled fuel injection device to which the rocker cover protection device of the present invention is applied. 1 is a cylinder block, and 2 is mounted on the upper end of the cylinder block 1 via a gasket. The fixed cylinder head 3 is a rocker cover mounted and fixed on the upper end of the cylinder head 2 via a gasket. The rocker cover 3 has a general material, that is, a melting point of about 200 ° C. It is made of synthetic resin and is integrally formed.

At the front end of the cylinder head 2, a water temperature sensor 4 whose detection section faces a water jacket in the cylinder head is mounted, and a fuel injection valve 6 is mounted on a side intake branch 5. Have been.

Further, the fuel injection valve 6 has an injection port directed to a combustion chamber on the lower surface of the cylinder head 2 via an intake port, and a valve opening time, that is, a fuel supply amount is controlled by a control pulse signal from a controller 7. It is supposed to be.

The controller 7 has a microcomputer built therein. For example, the controller 7 uses a current signal based on an engine speed signal output from a crank angle sensor 8 in a distributor and an intake air amount signal output from an air flow meter 9 in an intake passage. Of the engine operating state of the fuel injection valve 6
, And performs control such as increasing the reference fuel amount when the engine is started at a low temperature based on the cooling water temperature signal output from the water temperature sensor 4. Further, the controller 7 is provided with a control circuit that cuts off the fuel supply from the fuel injection valve 6 based on the signal output from the water temperature sensor 4.

The control operation of the control circuit of the controller 7 will be described below with reference to FIG.

First, in section 1, it is determined whether or not the starter switch is turned on, that is, whether or not the engine has been started. In this section 2, it is determined from the detection signal from the water temperature sensor 4 whether or not the current cooling water temperature is 145 ° C. or higher. Where 14
The reference value of 5 ° C. is that the temperature transmitted from the cylinder head 2 heated by the combustion heat to the rocker cover 3 at about 145 ° C. is about 200 ° C. which is the melting point of the rocker cover 3.
It is to be near. Further, by setting the high heat of 145 ° C. as the reference value, the normal operation by the fuel cut described later is not hindered.

Accordingly, the water temperature in section 2 is 145.
° C or higher, the fuel injection from the fuel injection valve 6 is stopped in section 3 and
The fuel injection stop state is continued for a predetermined time by a timer. As a result, the operation of the engine is temporarily stopped, and the cylinder head 2 is cooled.
Overheating is prevented for thereby preventing the thermal deformation of the rocker cover 3 to <br/> advance. As a result, the shape of the rocker cover 3 is maintained, and good sealing performance between the cylinder head 2 and the rocker cover 3 can be maintained.

Further, since it is not necessary to form the rocker cover 3 from a synthetic resin material having high heat resistance, it is advantageous in terms of cost. Since the measurement is performed using the existing water temperature sensor 4 provided, an increase in cost can be suppressed.

When the supply of fuel is stopped in section 3, a signal for turning on an indicator light provided with instruments on the instrument panel is output in section 5. The indicator is turned on for a certain period of time by the timer of the section 4.

In sections 1 and 2, before the engine is started or when the water temperature is 145 ° C. or lower, the process is terminated.

[0019]

As is apparent from the above description, according to the protection device for a rocker cover made of synthetic resin according to the present invention, when the temperature of the cooling water of the engine rises close to the temperature corresponding to the melting point of the rocker cover. since the supply of fuel to be stopped by the control circuit of the controller, the melting point or more of overheating of the rocker cover can be suppressed, the thermal deformation of the rocker cover
Is prevented beforehand. As a result, the shape of the rocker cover is maintained, the sealing performance between the rocker cover and the cylinder head is prevented from deteriorating, and it is not necessary to use a synthetic resin material having high heat resistance, thereby suppressing an increase in cost.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram showing one embodiment of the present invention.

FIG. 2 is a flowchart illustrating a control operation by a controller according to the embodiment.

[Explanation of symbols]

2 ... cylinder head, 3 ... rocker cover, 4 ... water temperature sensor, 6 ... fuel injection valve, 7 ... controller.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) F02D 17/04 F02D 41/22 F02D 45/00

Claims (1)

(57) [Claims] A rocker cover made of synthetic resin provided at an upper end of a cylinder head, a water temperature sensor for detecting a temperature of engine cooling water, and output signals from the water temperature sensor and other sensors. A controller that controls the fuel supply amount of the engine in accordance with the operating state detected by the controller, wherein the controller determines that the temperature of the engine cooling water is close to the melting point of the rocker cover transferred from the cylinder head. A protection device for a rocker cover made of synthetic resin, comprising a control circuit for stopping fuel supply to the engine at a very high temperature.