JPH075202Y2 - Camshaft thrust bearing structure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a thrust bearing structure for a camshaft of an engine.

[Conventional technology]

In the double overhead camshaft type engine, a timing pulley that meshes with the timing belt is attached to the intake side camshaft, and the intake side camshaft is driven by the timing belt, while the exhaust side camshaft is driven from the intake side camshaft. There is one that transmits rotation via a helical gear.

As a prior art document disclosing such a double-haver head camshaft type engine, there is, for example, Japanese Patent Application No. 60-126292 filed by the present applicant on August 19, 1985.

Since the helical gears are used in the double overhead camshaft type engine as described above, a load is applied to both the intake side camshaft and the exhaust side camshaft in the axial direction. . Therefore, thrust bearings are used to support the intake-side camshaft and the exhaust-side camshaft.

Prior art documents disclosing thrust bearings include the above-mentioned Japanese Utility Model Application No. 60-126292 and Japanese Utility Model Application Laid-Open No. 54-165607.

FIG. 5 is a bottom view of a conventional camshaft thrust bearing structure. FIG. 5 is a bottom view of a cam cap that specifically supports the intake side camshaft of the double overhead camshaft type engine as described above.

In FIG. 5, 1 indicates the entire cam cap, and 2 indicates the sliding surface. The chain double-dashed line indicates the position of the intake side camshaft 15 attached to the cam cap 1. The cam cap 1 shown in FIG. 5 rotatably supports the intake-side cam shaft 15 as shown in FIG. 6 and is immovable in the axial direction. In FIGS. 5 and 6, the arrow F indicates the front of the engine. The arrow R indicates the rotation direction of the intake camshaft 15.

In FIG. 6, 11 is a journal part, and 12 and 13 are thrust supported parts. An oil passage 22 is bored inside the intake-side camshaft 15, and an oil hole 23 communicating with the oil passage 22 and an oil groove 24 aligned with the oil hole 23 are bored in the journal portion 11. There is. The arrow Z represents the flow of oil.

In FIG. 5, the thrust supported portions 12, 13 of the intake side camshaft 15 contact the cam cap 1 at the portions denoted by reference numerals 4 and 5, and the movement of the intake side camshaft 15 in the axial direction is prevented. It is being blocked. The oil passage 22 described with reference to FIG. 6 is for supplying oil for lubrication to the contact portion designated by the reference numeral 4 and the contact portion designated by the reference numeral 5.

[Problems to be solved by the device]

The conventional camshaft thrust bearing structure shown in FIG. 5 has a problem that noise is generated. This is for the following reason.

In FIG. 5, the thrust supported portion 1 of the camshaft 15
There is a slight gap between 2, 13 and the cam cap 1. On the other hand, when the engine is operating, the camshaft 15 undergoes torque fluctuations, and therefore tries to reciprocate in the axial direction. For this reason, the thrust supported portions 12, 13 of the camshaft 15 and the cam cap 1 impactly abut at the portions denoted by reference numerals 4 and 5. This is the reason why noise is generated in the conventional camshaft thrust bearing structure shown in FIG.

The present invention solves the above-mentioned problems of the prior art. The technical problem of the present invention is to prevent the thrust supported portion of the camshaft from coming into contact with the cam cap. It is to reduce noise.

[Means for Solving the Problems]

In order to achieve this technical problem, the following measures are taken in the present invention.

That is, it has a cam cap that is attached to the cylinder head of the engine and rotatably supports the cam shaft, and the thrust supported portions of the cam shaft come into contact with both side surfaces of the cam cap so that the cam shaft has its axial line In a thrust bearing structure of a cam shaft supported so as to move only a minute clearance in a direction, one end of the cam cap is opened in one side surface of the cam cap and the other end is slid in the sliding surface of the cam cap. An oil groove that ends in the moving surface, a circumferential groove that is provided on the outer peripheral surface of the camshaft and intersects the oil groove, one end that opens to the circumferential groove, and the other end that forms the oil supply passage. It is a means characterized by comprising an oil hole that opens.

[Action]

According to the above means, the oil holes serve to supply the oil from the oil supply passage to the circumferential groove, and the ills supplied to the circumferential groove are supplied to the oil groove intersecting with the circumferential groove. Here, since one end of the oil groove opens on one side surface of the cam cap and the other end ends in the sliding surface, most of the oil has oil grooves open on both side surfaces of the cam cap. It is supplied to the side of the person who is.

Therefore, on the side where the oil groove is opened, the hydraulic pressure between the cam cap and the thrust supported portion becomes very large, and this oil pressure causes a gap between the thrust supported portion of the camshaft and the cam cap. (Micro clearance)
On the other side, the thrust supported portion of the camshaft and the cam cap are kept substantially in contact with each other.

As a result, the camshaft is held in a state in which it can move axially only in the direction of shortening the above-mentioned distance, and even when a force acts in the direction of shortening the above-mentioned distance, the force is buffered by hydraulic pressure.

〔Example〕

FIG. 1 is a bottom view of a camshaft thrust bearing structure according to an embodiment of the present invention.

Specifically, FIG. 1 is a bottom view of a cam cap that supports an intake side camshaft of a double overhead camshaft type engine.

In FIG. 1, 1 represents the entire cam cap, and 2 represents the sliding surface. The chain double-dashed line indicates the position of the intake side camshaft 15 attached to the cam cap 1.

The cam cap 1 shown in FIG. 1 supports the intake side cam shaft 15 as shown in FIG. 2 so as to be rotatable and to move only a minute clearance in the axial direction. In FIGS. 1 and 2, the arrow F indicates the front of the engine. The arrow R indicates the rotation direction of the intake camshaft 15.

In FIG. 1, the cam cap 1 is provided with two bolt holes 31, one left and one right. By inserting a bolt (not shown) through the bolt hole 31, the cam cap 1 is fixed to a cylinder head (not shown). A knock pin receiving portion 32 for the knock pin is provided around the bolt hole 31 for inserting a knock pin (not shown) for positioning.

FIG. 2 is a side view of a part of the intake side cam shaft supported by the cam cap of FIG. 1 described above.

In FIG. 2, 11 is a journal part, and 12 and 13 are thrust supported parts. An oil passage 22 extending in the axial direction is bored inside the intake side camshaft 15, and an oil hole 23 communicating with the oil passage 22 and an oil groove 24 aligned with the oil hole 23 are formed in the journal portion 11. Has been drilled. The oil groove 24 extends in the circumferential direction of the journal portion 11. Arrow Z
Represents the flow of oil. The oil passage 22 penetrates through the intake camshaft 15 and has a plug at its tip.
33 is attached to prevent oil from leaking out.

A timing pulley (not shown) around which a timing belt (not shown) is wound around the tip of the intake side camshaft 15.
Is attached. Further, as can be seen from FIG. 2, the connection 34 between the journal portion 11 and the thrust supported portions 12 and 13 is provided with a radius.

Returning to FIG. 1, the thrust supported portions 12 and 13 of the intake side camshaft 15 are denoted by the same reference numerals in FIG. In FIG. 1, the thrust-supported portions 12, 1 of the intake-side camshaft 15 are designated by reference numerals 4 and 5.
3 comes into contact with the cam cap 1 to prevent the intake side cam shaft 15 from moving in the axial direction. The oil passage 22 described with reference to FIG. 2 supplies oil for lubrication to the abutting portion designated by reference numeral 4 and the abutting portion designated by reference numeral 5. It corresponds to the supply passage.

In FIG. 1, 35 is an oil seal. The oil seal 35 has an annular shape and is in contact with the outer periphery of the thrust supported portion 12 and the cam cap 1. The oil seal 35 is for preventing the oil supplied to the portion indicated by the reference numeral 4 from leaking to the outside.

The cam cap 1 of FIG. 1 and the intake side cam shaft 15 of FIG. 2 are attached to the engine as shown in FIG. FIG. 4 is a top view of a double overhead camshaft type engine provided with the camshaft thrust bearing structure of FIG. 1. Specifically, FIG. 4 is a view seen from above with the cylinder head cover removed.

In FIG. 4, reference numeral 15 is an intake side camshaft, and 16 is an exhaust side camshaft. A timing pulley 10 is attached to the tip of the intake side camshaft 15, and the intake side camshaft 15 is driven by driving the timing pulley 10 with a timing belt (not shown). The arrow R indicates the rotation direction of the intake camshaft 15. Arrow F
Is in front of the engine.

Rotation is transmitted from the intake camshaft 15 to the exhaust camshaft 16 via helical gears 17 and 18. The arrow S indicates the rotation direction of the exhaust side camshaft 16.

Since the helical gears 17 and 18 are used in the engine of FIG. 4, a load is axially applied to both the intake side camshaft 15 and the exhaust side camshaft shaft 16. Therefore, the thrust bearings 21 and 20 are used to support the intake side camshaft 15 and the exhaust side camshaft 16. The bottom view of the cam cap 1 of the thrust bearing 21 is the above-mentioned FIG. 1 and the cam cap 9 of the thrust bearing 20.
Is a bottom view of FIG. 3 described later.

In FIG. 4, 36 is a bolt for fixing the cam cap 1 (or the cam cap 9) to the cylinder head 41. Reference numeral 42 denotes a cam attached to the intake side camshaft 15 and the exhaust side camshaft 16. The intake / exhaust valve (not shown) is driven by this cam.

In FIG. 4, both the intake side camshaft 15 and the exhaust side camshaft 16 try to shockly reciprocate in the axial direction due to torque fluctuation. Further, considering the direction of the teeth of the helical gears 17 and 18 and the rotation direction of the intake side camshaft 15 (arrow R), the intake side camshaft 15 will move toward the arrow B during engine operation.
A force tends to be applied in the direction, and the exhaust side camshaft 16 tends to be pressed in the direction of arrow C. Therefore, in FIG. 1, the gap designated by the reference numeral 4 has almost no gap, but the gap designated by the reference numeral 5 tends to be large. Taking the intake side camshaft 15 of FIG. 4 as an example, when the intake / exhaust side (not shown) is closed, the cam 42 is pushed up by the valve spring (not shown), so that the intake / exhaust valve is closed each time. The intake camshaft 1 tries to move in the direction of arrow C. In connection with this point, referring to FIG. 1, the idea of this embodiment is to always press the intake side camshaft 15 in the direction of arrow B by hydraulic pressure during engine operation. This will be described in detail.

As can be seen from FIG. 1, the sliding surface 2 of the cam cap 1 is provided with an oil groove 51. The oil groove 51 extends at an angle θ with respect to the axial direction PP of the intake side camshaft 15. As can be seen from FIG. 1, one end 52 of the oil groove 51 is opened to the inner side surface 53 of the cam cap 1, but the other end 54 is not opened to the outer side surface 56 of the cam cap 1, and the oil groove 51 is slid. It is finished in the moving surface 2. Here, the inner surface 53 of the cam cap 1 is the cam cap 1
In the above, the inside surface of the cylinder head is meant, and the outside surface 56 means the surface outside the cylinder head in the cam cap 1.

As you can see by comparing Figure 1 and Figure 2, the oil groove
Since 51 intersects with the oil groove 24, oil is constantly supplied to the oil groove 51 via the oil groove 24 during engine operation. However, as mentioned earlier, the oil groove 51
One end 52 of the cam cap 1 is opened to the inner side surface 53 of the cam cap 1, but the other end 54 is not opened to the outer side surface 56 of the cam cap 1, so most of the oil flows as indicated by the arrow W, Is supplied to the abutting portion marked with. Therefore, the hydraulic pressure in such a part becomes very large. In other words, due to the hydraulic pressure, a certain distance is maintained between the thrust supported portion 13 of the intake side camshaft 15 and the cam cap 1 in the portion denoted by the reference numeral 5, and in the portion denoted by the reference numeral 4. The thrust supported portion 12 and the cam cap 1 are kept substantially in contact with each other.

Therefore, the intake side camshaft 15 has arrows B, C in the axial direction.
Even if a large force is applied in the direction, the intake-side camshaft 15 can move only in the C direction, which reduces the above-mentioned interval, so that the cam cap 1 and the thrust supported portion 12 are impacted by the movement in the B direction. No contact occurs. Also, C
Since the force in the direction is buffered by the above-mentioned hydraulic pressure, no shocking contact between the cam cap 1 and the thrust supported portion 13 occurs.

Therefore, according to this embodiment, the noise generated from the intake side camshaft 15 is reduced.

The above-mentioned matters also apply to the exhaust side camshaft 16. FIG. 3 is a bottom view of the thrust bearing structure for the exhaust side camshaft. Specifically, FIG. 3 is a bottom view of the cam cap 9 of the thrust bearing 20 of FIG.

In FIG. 3, 9 indicates the entire cam cap, and 2 indicates the sliding surface. The cam cap 9 shown in FIG. 3 rotatably supports the exhaust side cam shaft 16 so as not to move in the axial direction. The arrow F represents the front of the engine.
The arrow S indicates the rotation direction of the exhaust side camshaft 16.

In FIG. 3, reference numerals 12 and 13 denote thrust supported portions of the exhaust side camshaft 16. The exhaust side camshaft 16 is also provided with an oil passage, an oil hole and an oil groove as shown in FIG. 2 (see reference numerals 22, 23 and 24 in FIG. 2), but these are omitted in FIG. ing.

In FIG. 3, the thrust supported parts 12, 13 of the exhaust side camshaft 16 come into contact with the cam cap 9 at the portions denoted by reference numerals 4 and 5, and the exhaust side camshaft 16 moves axially. Has been blocked. In FIG. 3, the oil seal shown in FIG. 1 (see reference numeral 35 in FIG. 1) is not used. This is because that shown in FIG. 3 is arranged in the cylinder head cover (see FIG. 4).

In FIG. 3, 51 is an oil groove provided on the sliding surface 2 of the cam cap 9. The oil groove 51 is provided at an angle θ in the axial direction PP direction of the exhaust side camshaft 16. One end 52 of the oil groove 51 is the cam cap 9
However, the other end 54 is not opened to the outer side surface 56 of the cam cap 9.

Also in the case of FIG. 3, the oil groove 51 and the exhaust side camshaft 16
Since it intersects with the oil groove (not shown),
Oil is always supplied to the 51 while the engine is running.
However, as described above, one end 52 of the oil groove 51 is
Is opened on the inner surface 53 of the cam cap 9, but the other end
Since 54 is not opened on the outer side surface 56 of the cam cap 9, most of the oil is supplied to the portion indicated by the reference numeral 5 as shown by the arrow W. In other words, due to the hydraulic pressure, in the portion denoted by reference numeral 5, a certain space is maintained between the thrust supported portion 13 of the exhaust side camshaft 16 and the cam cap 9, and the portion denoted by reference numeral 4 is provided. Then,
The thrust supported portion 12 and the cam cap 9 are kept substantially in contact with each other.

Therefore, even if a large force is applied to the exhaust side camshaft 16 in the directions of the arrows B and C, the cam cap 9 and the thrust supported portions 12 and 13 are impacted with each other in the same manner as in the embodiment shown in FIG. There is no contact.

Therefore, according to this embodiment, the noise generated from the exhaust side camshaft 16 is also reduced.

Returning to FIG. 1, the other end 54 of the oil groove 51 is the cam cap 1
The oil hardly flows toward the oil seal 35 because it is not opened to the outer surface 56 of the. Therefore, according to the present embodiment, it becomes more difficult for oil to leak from the oil seal 35. This point is also a feature of this embodiment. Note that the abutting portion designated by reference numeral 4 can be sufficiently lubricated with oil that oozes out from the gap between the journal portion 11 of the exhaust side camshaft 15 and the sliding surface 2.

Finally, in this embodiment, the oil groove 51 is formed in the camshaft 15
Alternatively, it is provided with an angle θ with respect to the 16 axial directions PP, for the following reason.

That is, when the oil groove 51 is provided parallel to the axial direction of the cam shaft 15 or 16, the ability of the cam cap 1 or the cam cap 9 to support the cam shaft 15 or 16 in the portion where the oil groove 51 exists. Can be significantly reduced. Then, that part will wear out early. On the other hand, the oil groove 51 should be
If a certain angle is provided with respect to the axial direction of 15 or 16, the load bearing capacity of the cam cap 1 or the cam cap 9 is replaced by the oil groove 51 instead of the oil groove 51 in most of the sliding surface 2. Since there is little decrease in
The cam cap 1 or the sliding surface 2 of the cam cap will not be prematurely worn. This is the reason why the oil groove 51 is provided at a certain angle with respect to the axial direction of the camshaft 15 or 16.

Although the specific embodiment of the present invention has been described above, the present invention is not limited to this embodiment, and various embodiments are included within the scope of the utility model registration claim.

[Effect of device]

According to the present invention, one end of the oil groove opens to one side surface of the cam cap, and the other end ends in the sliding surface.
Due to the hydraulic pressure applied to the side surface where the oil groove is opened, the space between the thrust supported part of the cam shaft and the cam cap is maintained on the side surface where the oil groove is opened, and on the other side surface, The cam cap and the thrust supported portion are kept substantially in contact with each other.

Therefore, the camshaft is held in a state of being axially movable only in the direction of reducing the above-mentioned distance, and the force applied in that direction is buffered by the hydraulic pressure, so that the cam cap and the thrust supported portion are impacted. No contact occurs, and the noise of the camshaft thrust bearing structure is reduced.

[Brief description of drawings]

FIG. 1 is a bottom view of a camshaft thrust bearing structure according to an embodiment of the present invention, FIG. 2 is a side view of an intake side camshaft supported by the cam cap of FIG. 1, and FIG. , A bottom view of the thrust bearing structure for the exhaust side camshaft, Fig. 4 is a top view of a double overhead camshaft type engine equipped with the camshaft thrust bearing structure of Fig. 1, and Fig. 5 is a conventional FIG. 6 is a bottom view of the thrust bearing structure of the cam shaft of FIG. 6, and FIG. 6 is a side view of the intake side cam shaft supported by the cam cap of FIG. 1 …… Cam cap 2 …… Sliding surface 9 …… Cam cap 12,13 …… Thrust supported part 15 …… Intake side camshaft 16 …… Exhaust side camshaft 41 …… Cylinder head 51 …… Oil groove 52 ...... One end of oil groove 53 …… Inside surface of cam cap (one side surface of cam cap) 54 …… Other end of oil groove 56 …… Outside surface of cam cap

Claims (1)

[Scope of utility model registration request] 1. A camshaft, which is attached to a cylinder head of an engine and rotatably supports a camshaft, wherein thrust supported portions of the camshaft are in contact with both side surfaces of the camcap to allow the camshaft to rotate. In the thrust bearing structure of the cam shaft, in which the shaft is supported so as to move only by a minute clearance, the one end of the cam cap is opened on one side surface of the cam cap and the other end is opened. An oil groove that ends within the sliding surface, a circumferential groove that is provided on the outer peripheral surface of the camshaft and intersects the oil groove, one end that opens into the circumferential groove and the other end A thrust bearing structure for a camshaft, comprising: an oil hole that opens into a supply passage.