JPH05280458A - Housing of spark plug - Google Patents

Abstract

(57) [Abstract] [Purpose] To make the cylinder head of the engine compact. [Structure] A pipe-shaped spark plug housing 63 is provided with a recess 64 so that the rocker shafts 21 and 22, which are the rocking centers of the rocker arms 33, can be brought closer to the engine center side.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spark plug housing for an engine.

[0002]

2. Description of the Related Art Generally, in opening / closing control of an intake valve and an exhaust valve in an automobile engine, an opening / closing timing is set in accordance with an operating state obtained from an engine speed, an accelerator depression amount, and the like. Then, in such a valve operating device, there has been proposed one in which the cam profile is changed in order to reduce fuel consumption at low speeds and to perform efficient intake and exhaust at high speeds, depending on operating conditions. .. This is done by changing the opening / closing timing of the intake valve and the exhaust valve, the lift amount, the opening period, etc. at low speed or high speed.

That is, in an automobile engine, a high speed cam and a low speed cam are provided on a cam shaft, and the high speed cam has a cam profile capable of obtaining a valve opening / closing timing corresponding to high speed operation. The cam has a cam profile that can obtain the valve opening / closing timing corresponding to low speed operation. By selectively using the high-speed cam or the low-speed cam according to the operating state while the engine is operating, it becomes possible to obtain the optimum opening / closing timing of the intake valve and the exhaust valve. There is.

Specifically, for example, the base end of a rocker arm is fixed to a rocker shaft, and a rocker arm for high speed is provided so as to be connectable and separable, and a rocking end of the rocker arm is brought into contact with an upper end portion of a valve for low speed operation. The cam and the high speed cam are engaged with the low speed rocker arm and the high speed rocker arm. That is, at low speed, the low speed cam swings the rocker arm to open and close the valve, and at high speed, the high speed rocker arm is coupled to the rocker shaft, and the high speed cam swings the rocker arm to open the valve. Is opened and closed.

In addition, in such an automobile engine, a cylinder deactivation mechanism which reduces fuel consumption by stopping two cylinders of a four-cylinder engine during idle operation or low-load operation, for example, is conventionally used. Proposed. That is,
In the valve train, the piston operates during idle operation or low load operation, but the operation of the intake valve and the exhaust valve is stopped so that fuel is not supplied.

As a concrete structure example, the base end of the rocker arm is fixed to the rocker shaft, the low speed rocker arm and the high speed rocker arm are provided so as to be connectable and separable, and the rocking end of the rocker arm contacts the upper end of the valve. It has a structure in which the low speed cam and the high speed cam are connected to the corresponding low speed rocker arm and high speed rocker arm respectively. In this structure, the low speed rocker arm is connected to the rocker shaft at low speeds, the valve is opened and closed by the low speed cam, the high speed rocker arm is connected to the rocker shaft at high speed, and the valve is opened and closed by the high speed cam. By separating the low-speed rocker arm and the high-speed rocker arm from the rocker shaft,
The stopped state of the valve operation, that is, the cylinder deactivated state is achieved.

[0007]

When the valve operating device as described above is mounted, since a switching mechanism is provided, an extra space is taken up and the cylinder head becomes large. However, the cylinder head should be as small as possible in consideration of mounting in the engine room and the layout of the intake pipe and exhaust pipe. This also applies to an engine that does not have a valve train.

[0008]

In order to solve the above problems, according to the present invention, a recess is provided at a location facing another member in a pipe-shaped plug housing that covers an ignition plug mounted on a cylinder head of an engine. is there.

[0009]

Since the recess is provided in the plug housing, for example, the rocking center of the rocker arm can be moved closer to the center side, and as a result, the camshaft and the like can be moved closer to the engine center side, and the cylinder head can be made compact. Can be achieved.

[0010]

1 shows a cross section of an embodiment in which the present invention is applied to an engine equipped with a valve operating device with a cylinder deactivation mechanism, and FIG.
FIG. 3 shows a cross section taken along the line AA, and FIG. 3 shows a plane of the entire engine. The cross section taken along the line BB of FIG. 3 corresponds to FIG. 1.

First, an outline of an engine to which the present invention is applied will be described. This engine has a double over head with two camshafts on the cylinder head.
It is a camshaft type engine (DOHC), which is a four-cylinder engine having two valves for intake and two valves for exhaust.
The cylinder head 11 is provided with a pair of intake camshaft 12 and exhaust camshaft 13 which are parallel to each other along the longitudinal direction thereof, and a low speed cam 14 and a large cam 14 each having a small lift amount for each cylinder. A high speed cam 15 having a lift amount is integrally formed. The pair of cam shafts 12 and 13 are rotatably supported by the cylinder head 11 while being held between the upper portion of the cam shaft housing 16 and the plurality of cam caps 17.

Further, the cylinder head 11 has a pair of intake rocker shafts 21 and exhaust rocker shafts 22 which are parallel to each other along the longitudinal direction thereof and are parallel to the pair of cam shafts 12 and 13. Are provided for each. And this pair of rocker shafts 2
1, 22 are held by a lower portion of the camshaft housing 16 and a plurality of rocker shaft caps 23, and are rotatably supported by the cylinder head 11.

Each rocker shaft 21, 22 has a valve operating device that can be switched between a valve opening / closing timing for high speed operation and a valve opening / closing timing for low speed operation, a valve opening / closing timing for high speed operation, and a valve opening / closing timing for low speed operation. It is equipped with a valve operating device which can be switched to the cylinder and can be deactivated during low load operation. That is, as shown in FIG. 3, the valve operating devices 31 of the upper and lower two cylinders of the four cylinders have a cylinder deactivating mechanism, and the valve operating devices 32 of the central two cylinders do not have a cylinder deactivating mechanism.

The valve operating devices 31 and 32 have the same structure on the intake side and the exhaust side, and the valve operating device 3 does not have a cylinder deactivation mechanism.
2, a rocker arm 33 is integrally provided on a rocker shaft 22, and a rocker arm 35 for high speed is attached next to the rocker arm 33 so that the rocker shaft 22 can be coupled and separated. The rocker arm 33 has a swing end at an upper end of a valve 51. The low-speed cam 14 and the high-speed cam 15 on the camshaft 13 are engaged with the roller bearings 38 and 39 provided on the rocker arms 33 and 35, respectively.

Therefore, when the high speed rocker arm 35 is separated from the rocker shaft 22, the low speed cam 14 swings the rocker shaft 33 to open and close the valve 51, and the high speed rocker arm 35 moves. When coupled with the high speed rocker arm 35, the rocker arm 33 swings integrally with the high speed rocker arm 35 to open and close the valve 51. The coupling / separation of the high speed cam 15 and the cam shaft 12 is performed by hydraulic pressure according to the operating condition of the engine.

The valve operating device 31 has a low speed rocker arm 34 and a high speed rocker arm 35 mounted on both sides of the rocker arm 33, and the low speed rocker arm 34 and the high speed rocker arm 35 are controlled by hydraulic control according to the operating condition of the engine.
Is coupled to and separated from the rocker shaft 22. By separating the rocker arms 34 and 35 from the rocker shaft 22, a cylinder deactivated state in which the rocker arm 33 does not open or close the valve 51 is achieved.

In this engine, an ignition plug 61 is attached to the combustion chamber 62 at a position corresponding to the center of each cylinder of the cylinder head with its tip facing the combustion chamber 62. The spark plug 61 is covered with a pipe-shaped spark plug housing 63, and an upper portion thereof is held by the cover 24.

The spark plug housing 63 is located between the main rocker arm 33 of the valve operating device on the intake side and the exhaust side. Therefore, as shown in FIGS. 1 and 2, a concave portion 64 is provided at a portion of the body portion facing the main rocker arm 33. By providing the recess 64, the rocking center of the rocker arm 33 can be moved closer to the center side without interfering with the spark plug housing 63. Therefore, the camshafts 22 and 23 can also be moved toward the engine center side. The upper width of the cylinder head can be made smaller.

The recess 64 is formed by flatly crushing a part of the pipe-shaped spark plug housing 63, and the inner dimension L thereof is the nut portion 65 of the spark plug 61.
Make it as large as possible so that tools that can be attached to and detached from can pass through.

The present embodiment is applicable not only to an engine equipped with a valve operating device, but also to a normal engine, and in that case, the arrangement intervals of the peripheral members can be reduced, so that the cylinder head can be made compact. Can be achieved.

[0021]

According to the housing of the spark plug according to the present invention, the pipe-shaped housing is provided with the recess so that the space between the housing and the peripheral member such as the rocker arm can be narrowed as much as possible. Can be made compact. Further, since it is not necessary to cut a part of the rocker arm or the like to achieve compactness, the rigidity of each member can be maintained.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an engine upper portion including a spark plug housing according to an embodiment.

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

FIG. 3 is a half view of an engine to which the present invention is applied.

[Explanation of symbols]

 11 Cylinder Head 12,13 Cam Shaft 14 Low Speed Cam 15 High Speed Cam 16 Cam Shaft Housing 17 Cam Cap 21,22 Rocker Shaft 31,32 Valve Operating Device 33 Rocker Arm 34 Low Speed Rocker Arm 35 High Speed Rocker Arm 51 Valve 61 Spark Plug 63 Spark plug housing 64 recess

Claims (1)

[Claims] 1. A housing for an ignition plug, characterized in that a recess is provided at a location facing another member in a pipe-shaped plug housing that covers an ignition plug attached to a cylinder head of an engine.