Assembling arrangement for tensioner and hydraulic control...

Internal-combustion engines – Poppet valve operating mechanism – Camshaft drive means

Reexamination Certificate

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Details

C123S090120, C123S1950HC, C123S19800E

Reexamination Certificate

active

06332441

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates to an assembling arrangement for a tensioner and a hydraulic control valve in an internal combustion engine. In addition, the present invention relates to an oil passage arrangement for supplying an oil pressure to a tensioner for a camshaft driving chain. Further, the present invention relates to a mounting structure of a hydraulic control valve in the internal combustion engine.
In engines in which the rotation of a crankshaft is transmitted to a camshaft via a chain/sprocket mechanism, an engine is known which uses a tensioner using a plunger adapted to be pushed out by virtue of oil pressure in order to maintain the tension of a chain constant (refer to Japanese Utility Model Registration No. 2503434).
A tensioner such as described above, however, requires an oil passage to be formed so as to supply an oil pressure for imparting a thrust to the plunger in response to the slackness of the chain and an oil filter to be provided so as to prevent the intrusion of sludge or the like into the oil passage so formed. This construction has created a need for reducing production costs of such engines. This is a first problem in the conventional technique.
In addition, an engine has been put into practical use which is provided with a variable valve train as hydraulically controlled equipment in which intake and exhaust valve operation timings are automatically variable in response to the running condition of the engine, and cars equipped with the variable valve train are already sold in the market place.
This variable valve train is adapted to select connection or disconnection between a plurality of rocker arms pivotally supported on a rocker shaft using a switch-over device for hydraulic operations, and this valve train requires a control valve for connecting and/or disconnecting the oil pressure to be applied to the switch-over device and an oil passage for supplying the oil pressure to the switch-over device via the control valve (refer to JP-B-9-10104U).
In the aforesaid prior art, the control valve is attached to an end surface of a cylinder head on a transmission side thereof or an end surface opposite to a mounting surface where a camshaft driving mechanism is mounted.
An engine compartment of a small-sized car is more spacious in a transverse direction than in a longitudinal direction, and therefore, with a transversely mounted engine in which the crankshaft is made parallel with the axle, the serviceability for maintenance can be secured by providing the control valve on an end surface of the cylinder head on a transmission side in a direction of the crankshaft, or an end surface opposite to a mounting surface where the camshaft driving mechanism is mounted. With a longitudinally mounted engine in which the crankshaft is disposed perpendicular to the axle, considering the serviceability for maintenance in the engine compartment, it is difficult to provide the control valve on the rear end surface of the cylinder head in the crankshaft direction or on the end surface on the transmission side.
It is further difficult to mount the control valve on the side of the cylinder head or cylinder block where in intake manifold and the exhaust manifold are mounted at a position causing no problem with servicing for maintenance. In addition, if the control valve were to be so mounted, it will tend to result in the enlargement of the engine in size.
It is possible to try to provide the control valve at a position spaced away from the engine main body, but if such is tried, it will inevitably result in an increase in man hours for production. This is a second problem in the conventional technique.
SUMMARY OF THE INVENTION
The present invention was made with a view to solving the problems inherent in the conventional technique.
An object of a first aspect of the present invention is to provide an assembling arrangement for a tensioner and a hydraulic control valve in an internal combustion engine which is an improvement without involving an increase in the production costs.
In addition, an object of a second aspect of the present invention is to provide an oil passage arrangement for a tensioner that is improved without involving an increase in the production costs.
Further, an object of a third aspect of the present invention is to provide a mounting arrangement for a hydraulic control valve which is mountable on a cylinder head for an internal combustion engine without causing any problems in servicing for maintenance or involving an increase in man hours required for production.
The object of the first aspect of the present invention can be achieved by an assembling arrangement for a tensioner and a hydraulic control valve in an internal combustion engine, the assemblying arrangement comprising:
the tensioner, adapted to operate by virtue of the pressure of a lubricating oil, for applying tension to a camshaft driving chain; and
the hydraulic control valve, disposed close to said tensioner, for controlling an oil pressuresent to an equipment which is operated by virtue of the pressure of the lubricating oil,
wherein an oil passage for supplying an oil pressure to the tensioner is branched off from a downstream side of an oil filter provided at an inlet port of the hydraulic control valve.
The object of the second aspect of the present invention can be achieved by an oil passage arrangement for a tensioner, wherein a tensioner for a camshaft driving chain and a hydraulic control valve are disposed close to each other, and an oil passage for supplying an oil pressure to the tensioner is caused to branch off from a downstream side of an oil filter provided at an inlet port of the hydraulic control valve.
With these constructions according to the first and second aspects of the invention, the assembly arrangement, particularly the arrangement of the oil passage, can be simplified, and therefore, not only can man hours required for forming the oil passage be reduced, but also the number of components required can also be reduced by commonizing the oil filter. Moreover, the provision of the oil filter at the inlet port of the hydraulic control valve can securely prevent the intrusion of foreign matter into the hydraulic control valve and the tensioner. Furthermore, since the length of the oil pressure supply passage for the tensioner can be minimized, the response of the tensioner can be improved.
In particular, with an arrangement in which the hydraulic control valve is provided above the tensioner such that oil flows into the tensioner from thereabove, since the oil is prevented from being drained from the oil passage leading to the tensioner when the engine is stopped, air can be prevented from entering into the oil passage.
The object of the third aspect of the present invention can be achieved by a mounting structure of a hydraulic control valve in the internal cumbustion engine, wherein a casing portion adapted to accommodate therein a part of a driving mechanism for interlockingly rotating a crankshaft and camshafts is formed integrally with a cylinder head, and that a mounting portion of a hydraulic control valve and an opening of oil passages adapted to extend through the hydraulic control valve are provided in the casing portion.
With this construction, it is possible to mount the control valve at a position that does not interfere with the intake manifold and the exhaust manifold, and therefore, it is possible to secure high serviceability for maintenance. Moreover, the control valve can easily be connected to the oil passages formed in the cylinder head, and therefore, an increase in man hours required for production can be avoided. In particular, with a longitudinally mounted engine, on the side of the cylinder head where the exhaust manifold is mounted, generally the exhaust manifold is caused to extend in a direction in which the exhaust manifold is farther away from the end surface where the camshaft driving mechanism is mounted, the construction is advantageous in securing a required margin for the space for servicin

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