JP2019167891A - Lash adjuster - Google Patents

Abstract

To provide a lash adjuster which inhibits delay of movement of a valve body when the valve body closes a valve hole.SOLUTION: In a hydraulic lash adjuster 10, a plunger 21 which contacts with a rocker arm is housed in a body 11 so as to be displaceable along an extension direction of a center axis C1 of a body 11. A valve hole 25 is formed at a bottom wall part 24 of the plunger 21. The valve hole 25 allows communication between a storage chamber 28 that is an internal space of the plunger 21 and a filling chamber 15 that is a space between the body 11 and the plunger 21. The filling chamber 15 is provided with: a valve body 19 which can close the valve hole 25; and a retainer 31 which houses the valve body 19 and has a cylindrical shape with a closed bottom. Through holes 36A, 36D allowing communication between an interior and an exterior of the retainer 31 are provided at a bottom part 34 of the retainer 31.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a hydraulic lash adjuster.

  2. Description of the Related Art There is known a hydraulic lash adjuster in which a plunger abutting on a rocker arm is accommodated in a body that is displaceable along the axial direction of the bottomed cylindrical body. The lash adjuster includes a storage chamber, which is an internal space of the plunger, and a filling chamber, which is a space between the body and the plunger, as spaces into which hydraulic oil is introduced. Furthermore, the lash adjuster includes a valve hole that opens in a wall portion that partitions the storage chamber and the filling chamber, a valve body that can close the valve hole, and a retainer that accommodates the valve body. In such a lash adjuster, a spring that biases the valve body in a direction in which the valve hole is closed is provided inside the retainer.

  Patent Document 1 discloses a lash adjuster in which a spring that biases the valve body in a direction in which the valve hole is closed is omitted.

JP 2010-265874 A

  In the hydraulic lash adjuster, when the plunger is pressed by the rocker arm, the plunger is displaced in the direction in which the protruding length of the plunger from the body is shortened. At this time, hydraulic fluid flows from the filling chamber into the storage chamber through the valve hole. And if the pressure of a filling chamber becomes relatively larger than the pressure of a storage chamber in connection with a plunger being pressed, a valve hole will be obstruct | occluded by the valve body which moved to the valve hole side. When the valve hole is closed, the flow of hydraulic oil is blocked, and the displacement of the plunger is limited.

  As disclosed in Patent Document 1, in a lash adjuster in which a spring for urging the valve body in the direction in which the valve hole is closed is not provided in the retainer, when the plunger is pressed, There may be a delay in closing the valve hole. That is, when the plunger is pressed, the displacement amount of the plunger toward the inside of the body may increase.

  A lash adjuster for solving the above-described problem is a hydraulic lash adjuster, and a plunger having a top wall portion that comes into contact with the rocker arm is displaceable along the axial direction of the bottomed cylindrical body. It is accommodated in the body, and a valve hole is formed in the bottom wall portion of the plunger. The valve hole is a storage chamber that is an internal space of the plunger and a space between the body and the plunger. The hydraulic fluid is communicated with the filling chamber so that hydraulic oil flows in and out between the storage chamber and the filling chamber, and the plunger is provided in the filling chamber and biases the plunger in a direction in which the plunger protrudes from the body. A retainer that is provided in the filling chamber and that can close the valve hole; and a bottomed cylindrical retainer that is provided in the filling chamber and accommodates the valve body. Of Through hole communicating with the outside and to its gist that is provided at the bottom of the retainer.

  According to the above configuration, when the hydraulic oil flows from the filling chamber into the storage chamber through the valve hole, first, the hydraulic oil in the filling chamber flows from the outside of the retainer in the filling chamber into the retainer through the through hole. To do. At this time, since the through hole is provided at the bottom of the retainer, the hydraulic oil flows into and out of the retainer along the axial direction of the body. Therefore, when the hydraulic oil flows from the outside to the inside of the retainer, the inflow direction of the hydraulic oil and the direction in which the valve body moves to the side closing the valve hole are the same direction. As a result, the plunger is pressed by the rocker arm, and the plunger starts to move toward the inside of the body, and when the valve body accommodated in the retainer moves to the side closing the valve hole, the retainer moves from the outside to the inside. The movement of the valve body can be assisted by the flowing hydraulic oil. That is, when the plunger is pressed by the rocker arm and the plunger is displaced into the body, it is possible to promote the closing of the valve hole by the valve body and to realize the state where the displacement of the plunger is limited at an early stage.

The schematic diagram which shows the valve operating mechanism of the internal combustion engine with which one Embodiment of a lash adjuster is applied. Sectional drawing of the lash adjuster. The perspective view which shows the retainer with which the same lash adjuster is provided. The front view which shows the bottom part of the retainer with which the same lash adjuster is provided.

Hereinafter, the lash adjuster 10 which is one embodiment of the lash adjuster will be described with reference to FIGS.
As shown in FIG. 1, the lash adjuster 10 is provided in the cylinder head 91 and constitutes a valve operating mechanism of the internal combustion engine. The valve operating mechanism includes a rocker arm 99 that is pressed by a nose portion 98 of a cam 97 included in the camshaft 96. One end of the rocker arm 99 is supported by the engine valve 93, and the other end on the opposite side across the roller with which the cam 97 abuts is supported by the lash adjuster 10. When the engine valve 93 is opened, the lash adjuster 10 is pressed by the rocker arm 99 pressed by the nose portion 98 of the cam 97.

  As shown in FIG. 2, the body 11 of the lash adjuster 10 is disposed in a recess formed in the cylinder head 91. The body 11 is formed in a bottomed cylindrical shape including an outer wall portion 12 and a bottom plate 14. A supply port 13 that communicates the inside and outside of the body 11 is formed in the outer wall portion 12. A central axis C <b> 1 indicates the central axis of the body 11. The central axis C <b> 1 is a straight line indicating the axial direction of the body 11.

  A plunger 21 is accommodated in the body 11 so as to be displaceable along the central axis C1. The plunger 21 includes a cylindrical side wall portion 26, a hemispherical top wall portion 22 that covers one end of the side wall portion 26, a bottom wall portion 24 that covers the other end of the side wall portion 26, and a bottom wall portion 24. A projecting annular projection. The side wall portion 26 of the plunger 21 slides on the inner peripheral surface of the outer wall portion 12 in the body 11. As shown in FIGS. 1 and 2, the top wall portion 22 of the plunger 21 protrudes from the cylinder head 91, and the top wall portion 22 contacts the rocker arm 99. Although details will be described later, the plunger 21 is always urged in a direction in which the plunger 21 protrudes from the body 11 so that the top wall portion 22 contacts the rocker arm 99.

  As shown in FIG. 2, the internal space of the plunger 21 is partitioned as a storage chamber 28. A communication hole 27 that communicates the storage chamber 28 and the outside of the plunger 21 is formed in the side wall portion 26 of the plunger 21. Hydraulic oil is introduced into the storage chamber 28 from an oil supply path 92 formed in the cylinder head 91 via the supply port 13 of the body 11 and the communication hole 27 of the plunger 21. An outlet 23 that communicates the storage chamber 28 with the outside of the plunger 21 is formed in the top wall portion 22 of the plunger 21. Excess hydraulic oil in the storage chamber 28 flows out from the outlet 23 and is used as lubricating oil for each member.

  A space between the bottom wall portion 24 of the plunger 21 and the bottom plate 14 side of the body 11 is partitioned as a filling chamber 15. When the plunger 21 is displaced in the direction protruding from the body 11, the volume of the filling chamber 15 is increased. On the other hand, when the plunger 21 is displaced in the direction of returning to the inside of the body 11, the volume of the filling chamber 15 is contracted. A valve hole 25 that connects the storage chamber 28 and the filling chamber 15 is formed in the bottom wall portion 24 of the plunger 21. The hydraulic oil flows in and out between the storage chamber 28 and the filling chamber 15 through the valve hole 25.

  A retainer 31 is provided in the filling chamber 15. The retainer 31 has a bottomed cylindrical shape in which one end of the cylindrical portion 37 is closed by the bottom portion 34. A projecting portion 35 that protrudes into the retainer 31 is provided on the bottom portion 34. The opening 32 that is the other end of the cylindrical portion 37 of the retainer 31 has an inner diameter larger than the diameter of the valve hole 25. The opening 32 is provided with a flange portion 33. The flange portion 33 is attached to the surface on the filling chamber 15 side in the bottom wall portion 24 of the plunger 21.

  As shown in FIGS. 2 and 3, four through holes 36 </ b> A, 36 </ b> B, 36 </ b> C, 36 </ b> D are formed in the bottom 34 of the retainer 31. The interior and the exterior (filling chamber 15) of the retainer 31 communicate with each other through the through holes 36A to 36D. The through holes 36 </ b> A to 36 </ b> D are provided around the protrusion 35 at the bottom 34. Each of the through holes 36A to 36D has a circular shape. It should be noted that the cylindrical portion 37 of the retainer 31 is not formed with a hole that communicates the inside and the outside of the retainer 31.

  In the lash adjuster 10, when hydraulic oil flows from the filling chamber 15 into the storage chamber 28 through the valve hole 25, first, the hydraulic oil in the filling chamber 15 is moved from the outside of the retainer 31 in the filling chamber 15 to the inside of the retainer 31. Flows into the through holes 36A to 36D.

  As shown in FIG. 2, a spherical valve body 19 is accommodated in the retainer 31. The diameter of the valve body 19 is larger than the diameter of the valve hole 25. The valve body 19 closes the valve hole 25 by coming into contact with the opening of the valve hole 25 on the filling chamber 15 side. The valve body 19 is given a force that moves inside the retainer 31 based on the relative pressure difference between the hydraulic oil introduced into the filling chamber 15 and the storage chamber 28. When the pressure in the filling chamber 15 is relatively larger than the pressure in the storage chamber 28, a force that moves in the direction of closing the valve hole 25 acts on the valve body 19. When the pressure in the storage chamber 28 is relatively larger than the pressure in the filling chamber 15, a force that moves in a direction away from the valve hole 25 acts on the valve body 19. When the valve body 19 moves in a direction away from the valve hole 25 and is positioned on the bottom 34 side, the valve body 19 can be seated on a protrusion 35 provided on the bottom 34.

  Further, the filling chamber 15 is provided with a spring 51 that urges the plunger 21 via a retainer 31 in a direction in which the plunger 21 protrudes from the body 11. The spring 51 is provided between the flange portion 33 of the retainer 31 and the bottom plate 14 of the body 11.

  The positional relationship between the through holes 36 </ b> A to 36 </ b> D formed in the bottom 34 of the retainer 31 and the valve body 19 accommodated in the retainer 31 will be described with reference to FIG. 4. The center point C2 is a point indicating the center of the bottom 34. The center point C2 is located on a straight line obtained by extending the center axis C1 of the body 11 shown in FIG.

  As shown in FIG. 4, the four through holes 36 </ b> A to 36 </ b> D formed in the bottom portion 34 are arranged at equal intervals around the center point C <b> 2 of the bottom portion 34. FIG. 4 shows the valve body 19 in a state of being seated on the protrusion 35 provided in the bottom 34. The through holes 36 </ b> A to 36 </ b> D are opened at positions that cross the outline of the valve body 19 when viewed in the direction of the central axis C <b> 1 of the body.

Next, the effect of the lash adjuster 10 according to this embodiment will be described.
When the nose portion 98 of the cam 97 moves away from the rocker arm 99 as the camshaft 96 rotates, and the engine valve 93 starts to close, the rocker arm 99 tries to move away from the top wall portion 22 of the plunger 21. Since the plunger 21 is biased by the spring 51, the lash adjuster 10 follows the rocker arm 99 that the plunger 21 protrudes from the body 11 and attempts to separate from the top wall portion 22. As the plunger 21 protrudes from the body 11, the volume of the filling chamber 15 increases. When the pressure in the filling chamber 15 decreases as the volume of the filling chamber 15 increases, hydraulic oil flows from the storage chamber 28 into the filling chamber 15. As the hydraulic oil flows in, the pressure in the filling chamber 15 increases.

  On the other hand, when the nose portion 98 of the cam 97 contacts the rocker arm 99 and the engine valve 93 starts to open, the rocker arm 99 presses the plunger 21. The plunger 21 pressed by the rocker arm 99 tries to return to the body 11 but is blocked by the hydraulic oil in the filling chamber 15. That is, the displacement of the plunger 21 is limited. The hydraulic oil in the filling chamber 15 is compressed by the pressing force from the rocker arm 99. When the pressure in the filling chamber 15 becomes relatively higher than the pressure in the storage chamber 28, the valve body 19 closes the valve hole 25 and the flow of hydraulic oil between the storage chamber 28 and the filling chamber 15 is blocked. The When the displacement of the plunger 21 is restricted and the entire length of the lash adjuster 10 is fixed, the top wall portion 22 of the plunger 21 acts as a fulcrum of the rocker arm 99.

  In the lash adjuster 10, since the through holes 36 </ b> A to 36 </ b> D are provided in the bottom 34 of the retainer 31, the hydraulic oil flows into and out of the retainer 31 along the central axis C <b> 1 of the body 11. In FIG. 2, the inflow direction of the hydraulic oil that flows into the retainer 31 through the through holes 36A to 36D is schematically indicated by arrows. The inflow direction of the hydraulic oil flowing into the retainer 31 is the same direction as the extending direction of the central axis C1. That is, according to the lash adjuster 10, when the hydraulic oil flows from the outside of the retainer 31 to the inside, the flow direction of the hydraulic oil is the same as the direction in which the valve element 19 moves to the side closing the valve hole 25. Direction. Accordingly, when the plunger 21 is pressed by the rocker arm 99 and the plunger 21 starts to move toward the inside of the body 11, the valve body 19 accommodated in the retainer 31 moves to the side closing the valve hole 25. The movement of the valve body 19 can be assisted by the hydraulic oil flowing into the retainer 31 from the outside to the inside. That is, when the plunger 21 is pressed by the rocker arm 99 and the plunger 21 is displaced into the body 11, the valve body 25 is promoted to be closed by the valve body 19, and the state in which the displacement of the plunger 21 is limited is realized early. be able to.

  Furthermore, in the lash adjuster 10, as shown in FIG. 4, the through holes 36A to 36D are arranged at equal intervals around the center point C2. For this reason, the collision mode of the hydraulic oil flowing from the through holes 36 </ b> A to 36 </ b> D to the valve body 19 is likely to be uniform, and the movement of the valve body 19 is easily assisted.

  Further, in the lash adjuster 10, as shown in FIG. 4, the through holes 36 </ b> A to 36 </ b> D are opened so as to straddle the contour of the valve body 19. As a result, the hydraulic oil flowing from the through holes 36 </ b> A to 36 </ b> D easily collides with the valve body 19.

  Temporarily, when the hole which connects the inside and the exterior of the retainer 31 is opened in the cylinder part 37 of the retainer 31, it heads for the valve hole 25 by the hydraulic fluid which flows into the inside of the retainer 31 from the hole opened in the cylinder part 37. There is a possibility that the movement of the valve body 19 is suppressed. In this regard, according to the lash adjuster 10 in which the cylindrical portion 37 is not provided with a hole but the bottom portion 34 is provided with the through holes 36A to 36D, the valve body 19 is closed by the inflow of hydraulic oil into the retainer 31. Valve operation is not suppressed.

  The lash adjuster 10 is not provided with a spring that biases the valve body 19 in the closing direction. Accordingly, it is possible to prevent the valve body 19 from moving to the valve hole 25 side and closing the valve hole 25 when the top wall portion 22 of the plunger 21 is not pressed by the rocker arm 99. For example, when the nose portion 98 of the cam 97 is not in contact with the rocker arm 99 and the load from the cam 97 is not input to the lash adjuster 10, the plunger 21 may be displaced in a direction in which the plunger 21 protrudes from the body 11. According to the lash adjuster 10, it is possible to prevent the valve hole 25 from being blocked in such a state.

In addition, the said embodiment can also be implemented with the following forms which changed this suitably.
In the above embodiment, the protrusion 35 on which the valve body 19 is seated is provided on the bottom 34 of the retainer 31. The protrusion 35 is not an essential configuration. When the protrusion 35 is omitted, the valve body 19 can come into contact with the bottom 34.

  In the above embodiment, the four through holes 36 </ b> A to 36 </ b> D are provided in the bottom 34 of the retainer 31. The number of holes communicating the inside and the outside of the retainer 31 can be changed as appropriate. Regardless of the number of holes, it is preferable to arrange the holes at regular intervals around the center point C2.

  -In above-mentioned embodiment, although the through-holes 36A-36D are provided in the bottom part 34 as a circular hole, the shape of through-holes 36A-36D can be changed suitably. For example, a slit-shaped hole can be formed. Even in the case of a slit-like hole, it is preferable that the plurality of slit-like holes are arranged so as to be point-symmetric with respect to the center point C2.

  In the above-described embodiment, the through holes 36 </ b> A to 36 </ b> D that connect the inside and the outside of the retainer 31 are provided only on the bottom 34 of the retainer 31. The through-hole that communicates the inside and the outside of the retainer 31 can be formed in the cylindrical portion 37 in addition to the bottom portion 34. If the through holes 36 </ b> A to 36 </ b> D are formed at least in the bottom portion 34, an effect of assisting the movement of the valve body 19 can be achieved.

  As the hole that communicates the inside and the outside of the retainer 31, a slit-like hole that continues to the bottom part 34 and the cylindrical part 37 can also be adopted.

  DESCRIPTION OF SYMBOLS 10 ... Rush adjuster, 11 ... Body, 12 ... Outer wall part, 13 ... Supply port, 14 ... Bottom plate, 15 ... Filling chamber, 19 ... Valve body, 21 ... Plunger, 22 ... Top wall part, 23 ... Outlet, 24 ... Bottom wall part 25 ... Valve hole 26 ... Side wall part 27 ... Communication hole 28 ... Reservoir chamber 31 ... Retainer 32 ... Opening part 33 ... Flange part 34 ... Bottom part 35 ... Projection part 36A, 36B 36C, 36D ... through hole, 37 ... cylindrical part, 51 ... spring, 91 ... cylinder head, 92 ... oil supply passage, 93 ... engine valve, 96 ... cam shaft, 97 ... cam, 98 ... nose part, 99 ... rocker arm.

Claims (1)

A hydraulic lash adjuster, a plunger having a top wall portion that comes into contact with the rocker arm is housed in the body so as to be displaceable along the axial direction of the bottomed cylindrical body,
A valve hole is formed in the bottom wall portion of the plunger, and the valve hole communicates with a storage chamber that is an internal space of the plunger and a filling chamber that is a space between the body and the plunger. Hydraulic fluid flows in and out between the storage chamber and the filling chamber;
A spring provided in the filling chamber and biasing the plunger in a direction in which the plunger protrudes from the body; a valve body provided in the filling chamber and capable of closing the valve hole; and A bottomed cylindrical retainer that is provided and accommodates the valve body,
A lash adjuster in which a through-hole that communicates the inside and the outside of the retainer is provided at the bottom of the retainer.