JPS6039441Y2 - Sealed hydraulic lifter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a sealed hydraulic lifter, particularly suitable for constructing a transmission mechanism between a valve in a combustion chamber of an automobile engine and its driving cam, or for constructing a belt tensioner.

This type of hydraulic lifter has a cylindrical body and a plunger that slides within it.

The plunger itself is also cylindrical, with a reservoir inside.

A pressure chamber is defined by the pressure receiving end surface of the plunger and the inner peripheral surface of the body.

The pressure-receiving end surface of the plunger has a through hole with a check valve, and the reservoir communicates with the pressure chamber outside the plunger through this check valve in the forward direction.

The end of the plunger opposite to the pressure receiving surface is exposed outside the body, and is connected to an adjacent driven joint.

Oil is supplied into the pressure chamber from a reservoir, or conversely, oil is returned into the reservoir to allow a change in the volume of the pressure chamber and to displace the plunger within the body.

This displacement is taken out of the body and transmitted to the adjacent transmission member, and is used to eliminate backlash in the aforementioned cam transmission mechanism and to eliminate slack in the belt.

There is a so-called leak clearance between the outer circumferential sliding surface of the plunger and the inner circumferential surface of the body, and the oil in the pressure chamber passes through this leak clearance, further through the hole in the plunger body wall, and into the reservoir and into the orifice. Return while encountering resistance.

As described above, when changing the volume from within the pressure chamber, the plunger slides within the body.

By the way, the outer circumferential sliding surface of the plunger is sealed with the inner circumferential surface of the body, so that the above-mentioned leak clearance is sealed at this sealing point.
Prevents oil from leaking outside the body.

Conventionally, this type of seal rubs against the inner peripheral surface of the body when the plunger slides.

This seal deforms during this sliding, increases the pressure of the oil remaining in the annular groove in which the seal fits, and tends to increase the sliding resistance of the plunger in response to this pressure increase.

If the sliding resistance increases, the hydraulic lifter will malfunction.

The purpose of the present invention is to provide a hydraulic lifter which is free from the drawbacks of the conventional ones mentioned above, and in order to achieve this purpose, the hydraulic lifter of the present invention has an annular shape in which the above-mentioned seal is fitted. The groove is communicated with the through hole in the plunger body wall through a circuit having a circuit resistance smaller than the leak clearance.

In this circuit, the outer diameter of the plunger between the annular groove and the through hole is smaller than that of other leak clearance parts.

This small diameter portion allows the annular groove into which the seal fits and the reservoir to communicate through a circuit with low flow resistance.

As a result, the hydraulic pressure in the annular groove escapes into the reservoir without abnormally increasing the pressure, and the sliding resistance of the seal does not increase abnormally.

The main idea will be explained below with reference to the figures.

In FIG. 1, 1 indicates a cylinder block of an automobile engine, 2 a cylinder, 3 a piston, 4 a cylinder head, and 5 a combustion chamber.

6 is a port for supplying and exhausting air to the combustion chamber 5, and 7 is a valve that opens and closes this port.

8 is a valve guide, and 9 is a stem of the valve 7 that slides within this valve guide.

The compression coil spring 10 is attached to a retainer 11 at the end of the stem 9.
The valve 7 is always biased in the seating direction shown in the figure.

A rocker arm 14 is pivotally connected to the cylinder head 4, and its left end faces the free end of the stem 9, and its right end abuts against the upper end of the bushing rod 15.

The bushing rod 15 is supported by the cylinder block 1 so as to be vertically slidable.

The bushing rod 15 is connected to the cam 1 through the lower glue lid 17.
Linked to 8.

Lifter 17 slidably fits into hole 16 .

When the cam 18 rotates, the lid 17 and the bushing rod 15
The rocker arm 14 is swung through the steam 9, and the valve 7 is opened and closed through the steam 9, thereby supplying and exhausting air into the combustion chamber.

In FIG. 2, lifter 17 has a body 19. As shown in FIG.

A cylindrical plunger 20 is slidably fitted into the body 19.

21 is the head of the plunger 20.

The head 21 has a hemispherical concave seat 22 and a vent hole 2 to the outside air.
It has 3.

The interior of the plunger 20 is sealed with a diaphragm 24 in the form of an elongated bag.

The space between the diaphragm 24 and the inner peripheral surface of the plunger 20 serves as a reservoir 25 for storing oil.

The upper opening of the diaphragm 24 is pressure-sealed by a ring 26 from the inner periphery to the outer periphery, so that the reservoir 25 is sealed from the diaphragm 24.

The inside of the diaphragm 24 is open to the atmosphere through the ventilation hole 23.

A through hole in the plunger 20 communicates between the reservoir 25 and a leak clearance 28, and the leak clearance 28 communicates with a pressure chamber 29 below.

30 is a seal. A through hole 32 is provided in the lower bottom surface 31 of the plunger 20, and the downward opening of the through hole 32 serves as a valve seat 33.

A ball 34 is urged to be seated on the valve seat 33 by a spring 35, forming a check valve.

The retainer 36 receives one end of the spring 35 inside, and is pressed against the outer surface of the lower end of the plunger 20 by a large spring 37 at the outer peripheral flange.

The lower end of the large spring 37 is received on the inner bottom surface of the pressure chamber 29 .

38 at the upper end of FIG. 2 is a ring, and the plunger 20
Acts as a stopper to prevent the plunger from escaping.

Returning to FIG. 1, if there is a gap C as shown between the upper end of the stem 9 and the rocker arm 14, the large spring 37 at the bottom in FIG. let

As a result, through the seat 22 of the head 21, the bushing rod 1
5 (Fig. 1) upward and swing the rocker arm 14 counterclockwise to eliminate the gap C mentioned above.

At this time, the ball 34 opens, allowing oil in the reservoir 25 to flow into the pressure chamber 29 and allowing the plunger to slide.

When the bushing rod 15 is lifted up by the operation of the cam 18, the plunger 20 pressurizes the oil in the pressure chamber 29 due to the load.

At this time, the ball 34 closes and seals off the oil in the pressure chamber 29 to generate a load reaction force, thereby transmitting power to the transmission elements below the lifter 11.

In contrast to the above-mentioned clearance C, if the element between the stem 9 and the cam 18 receives a slow increase in compressive load due to thermal expansion or other reasons, the plunger 20 increases the volume of the pressure chamber 29 while compressing the spring 37. slide in the direction of shrinking.

Therefore, the oil in the pressure chamber 29 returns to the reservoir 25 via the leak clearance 28 and the continuous hole 27.

If the above-mentioned slow load increase suddenly changes, the above-mentioned load reaction force will be generated.

The lifter 11 operates as described above.

Next, we will explain the features of this proposal.

FIG. 3 shows an enlarged portion of the circle A indicated by the chain line in FIG.

Seal 30 fits within an annular groove 40 in the barrel wall of plunger 20.

This annular groove 40 communicates at a small diameter portion 41 with a through hole 27 located upstream of a pressure chamber 29 serving as a hydraulic pressure source.

This small diameter portion 41 is smaller than the leak clearance 28.
This is a circuit with less resistance.

The hydraulic lifter is operated by the plunger 20 and therefore by the seal 3.
0 rubs against the inner peripheral surface of the body 19.

In the structure of the conventional lid shown in FIG. 4, the annular groove 40' and the through hole 27' communicate with each other through a clearance having a relatively large resistance similar to the leak clearance 28'.

Therefore, the pressure of the oil in the annular groove 40' tends to rise abnormally during operation.

Under the influence of this abnormal pressure increase, the resistance of the seal 30' increased and the operation of the plunger 20' tended to become abnormal.

However, the annular groove 40 of the present invention has a small diameter portion 41 as described above.
Since the circuit with low resistance is connected to the reservoir 25 through the through hole 27, abnormal pressure rise is prevented.

Therefore, there is an advantage that the seal resistance of the seal 30 does not increase abnormally and the operation of the plunger 20 can be maintained smoothly.

Although a small diameter section 41 has been shown and described in the figures, it will be appreciated that this small diameter section could be replaced by several longitudinal grooves.

[Brief explanation of drawings]

Fig. 1 is a partial vertical cross-sectional view showing an example of an internal combustion engine equipped with the hydraulic lifter of the present invention, Fig. 2 is an enlarged longitudinal cross-sectional view of the hydraulic lifter of the present invention, and Fig. 3 is inside circle A in Fig. 2. FIG. 4 is an enlarged view similar to FIG. 3 of a conventional hydraulic lifter. 1...Engine block, 2...Cylinder, 3...Zeston, 6...Port,
7... Valve, 9... Stem, 14...
...Rocker arm, 15...Bush rod, 17...Hydraulic lifter, 18...
・Cam, 19...Body 20...Plunger, 21...Head, 25...
Reservoir, 29... Pressure chamber, 24...
Diaphragm, 27...Through hole, 28...
・Leak clearance, 30...Seal, 40
......Annular groove, 41...Small diameter part.

Claims (1)

[Scope of utility model registration request] A hollow body, a cylindrical plunger that can slide within the body, a pressure chamber defined within the body by the pressure-receiving end face of the plunger and the inner peripheral surface of the body, and a reservoir sealed within the cylindrical plunger with a diaphragm. , a vent hole in the plunger that opens the outer surface of the diaphragm to the atmosphere, a check valve that is held on the pressure-receiving end face of the plunger and allows the reservoir to flow only toward the pressure chamber, a spring that biases the plunger toward the reservoir, and a body wall of the plunger. A through hole that connects the reservoir inside the plunger to the outside of the plunger, a clearance between the outer circumferential surface of the plunger and the inner surface of the body, an annular groove provided on the outer circumferential surface of the plunger at a distance from the pressure chamber than the above-mentioned through hole; The outer diameter of the plunger between this annular groove and the above-mentioned through hole is smaller than the outer diameter of the plunger at other leak clearance points, and a clearance that communicates from the above-mentioned through hole to the annular groove is provided. A sealed hydraulic lifter characterized by a large .