JPH0138243Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a hydraulic lifter provided in a valve mechanism of an internal combustion engine for an automobile.

[Prior art and its problems] In a valve operating mechanism in which a rocker arm is pivotally supported so that it can swing, a cam is engaged with one end of the rocker arm to swing the rocker arm, and the other end operates a valve. In order to automatically absorb gaps caused by expansion and contraction of valves and wear of drive transmission parts, a hydraulic lifter is usually incorporated into the rocker arm to improve durability and reduce noise.

A hydraulic lifter built into a conventional rocker arm has a plunger, check valve, body, etc. built into the recess formed in the rocker arm as a unit, and is assembled into the unit from the oil chamber formed by the plunger and the recess. Oil is sent to and sealed in the high pressure chamber formed by the body and plunger through the check valve, and the mechanism absorbs the gap by the movement of the body. Publication No. 124209, Utility Model Publication No. 16708
Publication No.).

In this way, creating a hydraulic lifter with a two-stage structure in which the hydraulic lifter itself has an oil chamber and a high pressure chamber complicates the structure, increases the number of parts, and increases the weight of parts far from the center of oscillation. This increases the moment of inertia, which is disadvantageous for valve train mechanisms that are desired to be maintenance-free, have low noise, and have good motion characteristics by reducing the moment of inertia. Therefore, in order to meet these demands in the valve mechanism, only a high pressure chamber is provided in the plunger part of the hydraulic lifter, and no oil chamber or check valve is provided in the plunger part. It is desirable to have a single step. Various means and methods have been proposed for this one-stage process. As this type of hydraulic lifter, the present applicant previously proposed a plunger which was retractably inserted into a recess of the rocker arm, a high pressure chamber was formed by the recess and the plunger, the body was eliminated, and the high pressure chamber was formed in the rocker arm itself. A check valve is installed in the oil passage to simplify the structure of the plunger part of the hydraulic lifter, making it maintenance-free, reducing noise, and improving movement characteristics by reducing weight.
A single-stage plunger structure has been proposed that enables reliable and highly reliable operation.

On the other hand, in order to improve the motion characteristics of the rocker arm, it is necessary to reduce the weight of the rocker arm itself, and to reduce the weight of the rocker arm, the rocker arm is usually made of a light metal such as aluminum (including aluminum alloy). If the rocker arm body is made of a light metal such as aluminum, there is a risk that the rocker arm will be deformed or worn out by the lateral load component received by the hydraulic lifter. Further, the clearance of the sliding portion of the hydraulic lifter changes due to the difference in thermal expansion between the rocker arm and the hydraulic lifter, and oil leakage from the sliding portion may change the characteristics of the hydraulic lifter.

[Problems to be solved by the invention] In order to further improve the performance of the hydraulic lifter with a single-stage plunger structure previously proposed by the applicant, the invention aims to (a) make the rocker arm from a light metal such as aluminum; In this case, the rigidity against the lateral load component of the sliding part between the rocker arm and the hydraulic lifter is increased, (b) and the wear resistance of the sliding part is improved, and (c) the rigidity of the sliding part between the rocker arm and the hydraulic lifter is increased. The purpose is to stabilize the operating characteristics of a hydraulic lifter by reducing the difference in thermal expansion.

[Means for Solving the Problem] To achieve this object, the hydraulic lifter for an internal combustion engine of the present invention consists of the following. That is, a recess is formed in the rocker arm, a plunger is retractably inserted into the recess, a high pressure chamber is formed by the recess and the plunger, and the high pressure chamber and the inside of the rocker shaft are connected by an oil passage formed in the rocker arm itself. In the hydraulic lifter for an internal combustion engine, the oil passage is provided with a check valve that prevents the backflow of oil from the high pressure chamber to the inside of the rocker shaft, and the rocker arm is made of an aluminum-based material, and the recessed portion of the rocker arm is made of an iron-based material. An internal combustion engine characterized in that a pot-shaped member made of a material is attached and the plunger is slidably inserted into the pot-shaped member, and the plunger is made of the same iron-based material as the pot-shaped member. Hydraulic lifter.

[Function] With this configuration, the Rotsuka arm itself is
In addition to being constructed from lightweight materials, the plunger assembly is configured with only a high-pressure chamber without an oil chamber or check valve, which reduces the weight of the rocker arm and reduces the moment of inertia, resulting in good responsiveness of the valve mechanism. It is possible to achieve excellent movement characteristics. In addition, since we have attached a tip-shaped member made of iron-based material only to the concave part of the rocker arm for assembling the plunger, the rocker arm near the concave part for plunger assembly can withstand lateral loads while suppressing weight increase. Rigidity can be increased and wear resistance can be improved. In addition, by constructing the plunger of the hydraulic lifter with an iron-based material that has the same coefficient of thermal expansion as the tip-shaped member that is the sliding part of the plunger, the clearance between the tip-shaped member and the plunger changes due to thermal expansion. can be minimized. The rigidity and wear resistance of the sliding parts are improved, and changes in the sliding part clearance due to thermal expansion are suppressed, preventing the plunger from twisting and oil leaking from the high pressure chamber, resulting in stable hydraulic lifter operating characteristics. can get.

[Embodiments] Hereinafter, preferred embodiments of the hydraulic lifter for an internal combustion engine of the present invention will be described with reference to the drawings.

FIG. 1 shows a valve train incorporating a hydraulic lifter for an internal combustion engine according to a first embodiment of the present invention. In the figure, 1 is a valve assembled to a cylinder head 2, and 3 is a cam that rotates together with a camshaft 4. A rocker arm 6 that is swingably supported around a fixed rocker shaft 5 is provided between the valve 1 and the cam 3 to constitute a valve operating mechanism. One end of the rocker arm 6 is brought into contact with the cam 3, and the other end is brought into contact with the top surface of the valve 1 via a hydraulic lifter 7 built into the other end. In addition,
The valve 1 is urged upward by the valve spring 8, and when it is not pushed down by the rocker arm 6, the valve 1 is closed.

The main body of the rocker arm 6 is made of an aluminum material, which is a light metal. A cylindrical recess 9 is formed in the locker arm 6, and a pot-shaped member 15 made of an iron-based material is fixed to the recess 9 by casting or press fitting. Tip-shaped member 1
A plunger 10 made of a cylindrical iron-based member and having a bottom is inserted into the plunger 5 . The inner surface of the plunger 10 and the inner surface of the cup-like member 15 form a high-pressure chamber 11 in which oil is sealed. The plunger 10 is slidably fitted into a socket-shaped member 15, and the clearance between them is such that the rocker arm 6 is swung and the plunger 10 is slidably fitted into the valve 15.
When the hydraulic pressure inside the high pressure chamber 11 increases by pressing the high pressure chamber 11, the amount of oil leaking from the high pressure chamber 11 is suppressed to a clearance that is within an allowable value. The plunger 10 has a valve 1 on its bottom outer surface.
The inner surface of the bottom and the tip-shaped member 1
A return spring 12 made of a compression spring is interposed between the inner surfaces of the bottom portion of the return spring 5 .

The upper inner surface of the tip-shaped member 15 is formed in a stepped shape, and the stepped portion 13 can come into contact with the upper end surface of the plunger 10 when the plunger 10 moves upward. Therefore, the stepped portion 13 serves as a stopper for the movement of the plunger 10 in the direction opposite to the outlet of the tip-shaped member 15. A plunger 10 is provided at the lower part of the inner surface of the pot-shaped member 15.
Snap spring 14 as a stopper to prevent the
is fitted.

The pot-shaped member 15 is made of, for example, steel, cast iron, sintered alloy, or the like. The shape of the pot-shaped member 15 is formed to substantially follow the inner surface of the recess 9. The thickness of the tip-shaped member 15 is the same as that of the tip-shaped member 1.
The thickness is set so that the weight of 5 does not become too large, and the thickness is set to a value that does not destroy the tip-shaped shape in terms of rigidity and strength.

An oil passage 17 formed within the rocker arm 6 is connected to the high pressure chamber 11 . The oil passage 17 is communicated with the high pressure chamber 11 at one end, and communicated at the other end with an oil passage 18 in the rock shaft 5 formed by the hollow structure of the rock shaft 5 via a hole 19 in the rock shaft 5. . The oil passage 17 formed in the rocker arm 6 extends straight over its entire length, and has a high pressure chamber 1 in the middle.
A stepped portion 20 is formed with a diameter reduced toward the 1 side, and after being reduced in diameter, extends toward the high pressure chamber 11 and opens into the high pressure chamber 11 above the stepped portion 13 of the high pressure chamber 11. . Therefore, the opening 2 to the hyperbaric chamber 11
1 is a stepped portion 1 serving as a stopper for the plunger 10;
3 and is not blocked by the plunger 10.

The oil passage 17 is formed from the rock shaft 5 side toward the high pressure chamber 11 side. Since the end of the oil passage 17 opposite to the high pressure chamber 11 is closed by the rocker shaft 5, a special blind plug is not required. Therefore, there is no need for a machining hole and its blind plug on the high pressure chamber 11 side, as in the case of machining from the high pressure chamber 11 side.

A check valve 22 is provided at a stepped portion 20 in the middle of the oil passage 17. The check valve 22 includes a check ball 23 made of steel balls, a check ball 2
Check ball spring 24 consisting of a tapered compression spring that presses oil passage hole 2
It consists of a valve seat 26 having a diameter of 5.

Although not shown, engine oil is sent from the oil pump to the oil passage 18 in the hollow part of the rocker shaft 5 through the oil gear of the cylinder block and the oil passage in the cylinder head 2.

Next, the operation of the hydraulic lifter for an internal combustion engine according to the first embodiment of the present invention constructed as described above will be described below.

Oil sent to the oil passage 18 of the rock shaft 5 is sent to the high pressure chamber 11 through the hole 19, the oil passage 17, the check valve 22, and the opening 21.
The oil filled in the high pressure chamber 11 becomes high pressure when the plunger 10 is pressed by the valve 1, and this pressure is transmitted to the check valve 22, pushing the check ball 23 toward the rocker shaft 5, and the oil is The passage hole 25 is closed and high pressure oil is sealed in the high pressure chamber 11. Since oil is an incompressible fluid, when oil is sealed in the high pressure chamber 11, the driving force transmitted from the cam 3 to the rocker arm 6 is
The oil in the high pressure chamber 11 is directly transmitted to the valve 1 via the plunger 10. Now, when a gap is about to occur between the plunger 10 and the valve 1 in this driving force transmission system, the force with which the valve 1 presses the plunger 10 decreases, and the oil pressure in the high pressure chamber 11 decreases. When the oil pressure becomes smaller than the value obtained by subtracting the urging force of the check ball spring 24 from the pressure of the oil sent through the oil passage 17, the check ball 23 moves into the high pressure chamber 11.
Pushed to the side, the oil passage hole 25 opens and the high pressure chamber 1
1 is refilled with oil. When oil is replenished and the oil pressure in the high pressure chamber 11 is raised to an appropriate pressure again, the check ball 23 closes the oil passage hole 25 and the oil is confined in the high pressure chamber 11. Since the oil supply pressure from the oil passage 17 is constantly applied during engine operation, the oil pressure in the high pressure chamber 11 is automatically controlled to be maintained at a constant value by the action of the check valve 22. be done. The oil supply pressure in the oil passage 18 in the rock shaft 5 fluctuates considerably because lubricating oil is injected from the oil passage 18 toward various parts such as the cam 3, but the oil passage 17 itself has an appropriate volume. Cage oil passage 1
7 has a function as an oil supply chamber to the high pressure chamber 11 as well as a buffer chamber, so that fluctuations in the oil pressure in the oil passage 17 are maintained in a state where fluctuations are considerably suppressed. and check valve 22
By sealing oil into the high pressure chamber 11, pressure fluctuations are prevented from propagating into the high pressure chamber 11. By controlling the oil pressure in the high pressure chamber 11 to a substantially constant value, the plunger 10 is pressed against the valve 1 with a constant pressing force.
Gaps that tend to occur between the plunger 10 and the valve 1 due to wear, inertia of drive transmission parts, etc. are automatically absorbed.

Next, the operation regarding the sliding portion of the plunger 10 will be explained.

The hydraulic lifter is swung along a circular locus centered on the center of the rocker shaft 5, and the reciprocating motion of the valve 1 is a linear motion. Subject to lateral loads. Therefore, if the sliding part of the plunger 10 of the rocker arm 6 is made of a softer material than the plunger 10, the plunger 10
The lateral loads to which it is subjected can cause deformation and wear. Among these, the deformation is a deformation in which the wall of the portion of the recess 9 of the rocker arm 6 on the side far from the rocker shaft 5 tries to deform in the direction of moving away from the rocker shaft 5. When such deformation occurs, the plunger 10 becomes distorted. Otherwise, the gap will become larger. Furthermore, when wear occurs, the clearance of the sliding portion increases. Therefore, if deformation or wear occurs, sliding properties may deteriorate due to twisting, or gaps may cause oil leakage from the high pressure chamber 11 to the outside or air intrusion into the high pressure chamber 11, causing the hydraulic lifter to be damaged. 7 functions deteriorate. In the present invention, the main body of the rocker arm 6 is made of an aluminum material in order to reduce weight, and the sliding part of the plunger 10 is made of a tip-shaped member 15 made of iron material with excellent rigidity and wear resistance. 6
Deformation and wear of the sliding portion of the plunger 10 are prevented while the inertial force of the plunger 10 is reduced to ensure motion characteristics of the valve train with good followability.

Further, when the plunger 10 and the sliding portion on the rocker arm 6 side are made of materials having different coefficients of thermal expansion, the clearance therebetween changes depending on the difference in thermal expansion. If the clearance becomes small, the sliding characteristics of the plunger 10 will be impaired, if it becomes large, it will cause oil leakage or air intrusion, and a change in the clearance will deteriorate the operating characteristics of the hydraulic lifter 7. Since the plunger 10 is made of the same iron-based material as the tip-shaped member 15, the same thermal expansion occurs in the plunger 10 and the tip-shaped member 15, which is the sliding part thereof, and the clearance between them is maintained at a substantially constant amount. dripping By suppressing changes in the clearance due to thermal expansion, the sliding characteristics of the plunger 10 are maintained stably.

Next, FIG. 2 shows a second embodiment of the present invention.
In the second embodiment, the hydraulic lifter 7 of the present invention is built into the cam 3 side of the rocker arm 6. The basic configuration and operation of the sliding parts of the hydraulic lifter 7 and the plunger 10 are the same as in the first embodiment, and therefore redundant explanation will be omitted by assigning the same part numbers as in the first embodiment.

[Effect of the invention] As explained above, when using the hydraulic lifter for an internal combustion engine according to the invention, a high pressure chamber is formed between the recess of the rocker arm and the plunger, and the oil passage inside the rocker shaft is communicated with the high pressure chamber. In a hydraulic lifter of the type in which a check valve is installed in the oil passage, the rocker arm is made of a light alloy material such as aluminum, and a tip-shaped member made of an iron-based material is attached to the recessed part of the rocker arm where the plunger is assembled.
Since the plunger made of iron-based material is slidably inserted into the tip-shaped member, the rigidity of the tip-shaped member mounting portion of the rocker arm can be increased, and the sliding portion between the plunger and the tip-shaped member can be improved in wear resistance. In addition, changes in the clearance between the plunger and the sliding portion due to thermal expansion can be suppressed. As a result, it is possible to stably obtain good operating characteristics of the hydraulic lifter while ensuring the dynamic characteristics of the valve train with good responsiveness due to the weight reduction of the rocker arm and the reduction of the moment of inertia.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of a valve mechanism incorporating a hydraulic lifter for an internal combustion engine according to a first embodiment of the present invention;
FIG. 2 is a longitudinal cross-sectional view of a valve mechanism incorporating a hydraulic lifter for an internal combustion engine according to a second embodiment of the present invention. 1... Valve, 3... Cam, 5... Lock shaft, 6... Lock arm, 9... Recess, 10...
...Plunger, 11...High pressure chamber, 15...Cop-shaped member, 17...Oil passage, 22...Check valve.

Claims (1)

[Scope of Claim for Utility Model Registration] (1) A recess is formed in the rocker arm, a plunger is inserted into the recess so as to be retractable, a high pressure chamber is formed by the recess and the plunger, and the high pressure chamber and the inside of the rocker shaft are connected to the rocker arm itself. In the hydraulic lifter for an internal combustion engine, the rocker arm is made of an aluminum-based material, and the rocker arm is connected by a formed oil passage and is provided with a check valve in the oil passage to prevent backflow of oil from the high pressure chamber to the inside of the rocker shaft. A tip-shaped member made of an iron-based material is attached to the recess of the rocker arm, and the plunger is slidably inserted into the tip-shaped member, and the plunger is made of the same iron-based material as the tip-shaped member. A hydraulic lifter for an internal combustion engine, characterized in that: (2) attaching the tip-shaped member to the locking arm;
A hydraulic lifter for an internal combustion engine according to claim 1, which is mounted by either press-fitting or casting.