JPH1018814A - Valve timing control device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce size and weight of an engine and eliminate malfunction generated on a cam shaft and therearound while reducing the number of items in an internal combustion engine provided with a valve timing control mechanism. SOLUTION: Exhaust and intake cam shafts 11, 12 are rotatably installed to a cylinder head 14. The exhaust cam shaft 11 is provided with a timing pulley 22 through which driving force of a crank shaft is transmitted, a driving gear 35 which can be rotated relatively to the exhaust cam shaft 11, and a valve timing variable mechanism 30 which varies a phase of the driving gear 35 in a rotational direction in respect to the exhaust cam shaft 11 by hydraulic controlling. A driven gear 37 meshed with the driving gear 35 is fixed to an intake side cam shaft 16. A phase of the intake side cam shaft 16 is thus varied.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve timing control device for variably controlling the timing of an intake valve or an exhaust valve during operation of an internal combustion engine.

[0002]

2. Description of the Related Art A conventional valve timing control device is disclosed in, for example, Japanese Patent Application Laid-Open No. 4-209912. The structure of the first conventional valve timing control device will be described with reference to FIG. An exhaust-side camshaft 81 for the exhaust valve and an intake-side camshaft 82 for the intake valve are rotatably mounted on a cylinder head (not shown). Both camshafts 81 and 82 are arranged so as to be parallel to each other. A timing pulley 83 to which drive is transmitted from a crankshaft (not shown) is attached to a distal end of the exhaust camshaft 81. The exhaust camshaft 81 rotates together with the timing pulley 83 to operate an exhaust valve (not shown). A drive gear 84 is mounted on the exhaust side camshaft 81. The drive gear 84 rotates with the rotation of the exhaust-side camshaft 81.

A variable valve timing mechanism (VVT) 85 and a driven gear 86 are mounted on the intake side camshaft 82, and the driven gear 86 is engaged with the driving gear 84. Accordingly, the driving force of the exhaust camshaft 81 is transmitted from the driving gear 84 to the driven gear 86, and as a result, the intake camshaft 82 is rotated to operate an intake valve (not shown). The VVT 85 in this conventional example is a mechanism that changes the valve timing of the intake-side valve according to the operating conditions (load, rotation speed, etc.) of the internal combustion engine (engine).

In such a first conventional valve timing control apparatus, first, in a drive transmission system in a normal intake / exhaust movement of the camshafts 81 and 82, the drive is transmitted from the crankshaft to the timing pulley 83 and the exhaust side. The camshaft 81 is rotated. On the other hand, the rotation of the exhaust camshaft 81 is transmitted to the intake camshaft 82 via the drive gear 84 and the driven gear 86. In such a drive transmission system, when the operating condition changes and the VVT 85 is operated, the intake camshaft 82 is rotated by a displacement amount according to the operating condition, and the valve timing of the intake valve is changed. That is, the VVT 85 is mounted on the intake camshaft 82, and changes the phase of the intake camshaft 82 to change the valve timing on the intake valve side.

A second conventional valve timing control device having a structure shown in FIG. 8 will be described. Similarly to the above-mentioned conventional valve timing control device, an exhaust-side camshaft 81 on the exhaust valve side and an intake-side camshaft 82 on the intake valve side are rotatably mounted on a cylinder head (not shown). Both camshafts 81 and 82 are arranged so as to be parallel to each other. The exhaust side camshaft 81 is inserted into the connection tube 87 and is supported on the cylinder head via the connection tube 87.
A timing pulley 83 and a drive gear 84 are fixed to the connection tube 87. Drive is transmitted to the timing pulley 83 from a crankshaft (not shown). The drive gear 84 further transmits drive to the intake side camshaft 82 side. A VVT 85 is mounted on the exhaust side camshaft 81 outside the timing pulley 83. The rotation of the timing pulley 83 is transmitted to the exhaust camshaft 81 via the VVT 85. A driven gear 86 is mounted on the intake camshaft 82, and the driven gear 86 is meshed with a driving gear 84. The VVT 85 is the same as that of the first conventional example.

In such a second conventional valve timing control device, first, in the drive transmission system in the normal intake / exhaust movement of the camshafts 81 and 82, the drive is transmitted from the crankshaft to the timing pulley 83 and the VVT 8 is transmitted.
The exhaust-side camshaft 81 is rotated via 5.
On the other hand, the rotation of the timing pulley 83
7, transmitted to the driven gear 86 via the drive gear 84, and transmitted to the intake side camshaft 82. In such a drive transmission system, when the operating conditions change and the VVT 85 is operated, the phase of the exhaust-side camshaft 81 with respect to the connecting tube 87 is changed by the hydraulic control of the VVT 85. That is, the VVT 85 is mounted on the exhaust camshaft 81 and changes the phase of the exhaust camshaft 81,
The valve timing on the exhaust valve side is changed.

[0007]

However, such conventional valve timing control devices have the following disadvantages.

(1) In the first conventional example, the VVT 85 and the timing pulley 83 are separate camshafts 81,
82. Therefore, both camshafts 8
1, 82 are arranged close to each other,
It is necessary to displace the camshafts 81 and 82 in the axial direction so as not to interfere with the timing pulley 83. Then, compared to the case where both camshafts 81 and 82 are collectively mounted on either one of the camshafts 81 and 82,
2, a margin is required in the axial direction. As a result, the length of the engine becomes longer in the crankshaft direction, resulting in an increase in the size and weight of the engine itself.

(2) In the first conventional example, the VVT 85 is mounted on the intake camshaft 82, and the intake camshaft 82 is a variable camshaft. Therefore, the intake-side camshaft 82 includes the fixed shaft 82a and the rotating shaft 8
2b. Then, it is necessary to have a structure that supports the journals of the fixed shaft 82a and the rotating shaft 82b that rotate separately. Therefore, a bearing structure must be provided on the cylinder head to support the two journals, and the cylinder head has been increased in size and weight.

(3) In the second conventional example, the VVT 85 is mounted on the exhaust side camshaft 81 side and used as a variable side camshaft, and the intake side camshaft 82 is used as a direct connection side camshaft. Therefore, in order to directly transmit the rotation of the timing pulley 83 to the intake-side camshaft 82, the exhaust-side camshaft 81 must be provided with a connecting tube 87 for connecting the timing pulley 83 and the driving gear 84. In such a structure, the exhaust-side camshaft 81 is supported by the bearing of the cylinder head via the connecting tube 87, and since the thrust bearing is not provided directly on the bearing, rattling in the thrust direction is likely to occur. .

(4) In the exhaust-side camshaft 81 of (3), the hydraulic passage for driving the VVT 85 is formed so that oil is guided into the exhaust-side camshaft 81 from the bearing of the cylinder head due to its structure. In other words, the passage is communicated with the exhaust side camshaft 81 via the connection tube 87, so that oil easily leaks.

(5) Since the exhaust-side camshaft 81 of the second conventional example is supported by the bearing via the connecting tube 87, the journal diameter with respect to the bearing increases as a result.
As a result, the contact area between the bearing and the journal increases, resulting in an increase in mechanical loss and a decrease in fuel consumption rate. In addition, as the diameter of the journal increases, the reliability of the oil seal around the journal also decreases.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide an internal combustion engine having a valve timing control mechanism, in which the size and weight of the engine are reduced, and the number of parts is reduced. This is intended to solve the problem that occurs around the same mechanism.

[0014]

In order to achieve the above object, according to the first aspect of the present invention, a pair of camshafts for driving intake and exhaust valves are rotatably mounted on a cylinder head of an internal combustion engine. The first camshaft has a rotating body to which the drive from the crankshaft of the internal combustion engine is transmitted, the rotation of the first camshaft being transmitted to the second camshaft, and a rotation relative to the first camshaft. A movable drive gear and valve timing changing means for changing the phase in the rotation direction of the drive gear with respect to the first camshaft by hydraulic control are mounted, while the second camshaft is provided with the same drive gear. The driven gear to be meshed is fixed. Therefore, since the rotating body and the valve timing changing means are mounted on the first camshaft, there is no interference between them. The rotation of the first camshaft is transmitted from the drive gear via the driven gear to the second camshaft. on the other hand,
The valve timing changing means is mounted on the first camshaft on the directly connected side, and the phase in the rotation direction of the drive gear changed with respect to the first camshaft by the changing means is transmitted to the second camshaft via the driven gear. It is transmitted to the shaft side.

According to a second aspect of the present invention, in addition to the configuration of the first aspect, the rotating body is mounted near the shaft end with respect to the mounting position of the drive gear and the valve timing changing means. . Therefore, there is no interference between the driven gear fixed to the second camshaft and the rotating body of the first camshaft. Further, in the invention of claim 3, in addition to the structure of the invention of claim 2, the rotating body is arranged outside the cylinder head, and the drive gear and the valve timing changing means are arranged inside the cylinder head. . Therefore,
The rotating body is exposed outside the cylinder head, and the drive gear and the valve timing changing means are sealed inside the cylinder head.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of a valve timing control device for an internal combustion engine according to the present invention will be described below with reference to FIGS.

First, an outline of a drive transmission system of the apparatus according to the present embodiment will be described with reference to FIG. Exhaust side camshaft 1
1, a timing pulley 22 and a valve timing mechanism (VVT) 30 are mounted. Timing pulley 2
2 is rotatable integrally with the exhaust-side camshaft 11. The drive gear 35 is mounted on the exhaust camshaft 11 so as to be relatively rotatable. A drive gear 35 is fixed to the VVT 30 so as to be integrally rotatable. Intake side camshaft 1
A driven gear 37 is fixed to 6 so as to be integrally rotatable.
It is meshed with the drive gear 35. Exhaust side camshaft 1
The rotation of 1 is transmitted to the intake side camshaft 16 via the drive gear 35 and the driven gear 37. A change in the phase of the drive gear 35 in the rotation direction with respect to the exhaust camshaft 11 due to the operation of the VVT 30 is transmitted to the intake camshaft 16 via the driven gear 37.

Next, the apparatus of this embodiment is shown in FIGS.
This will be described in more detail with reference to FIGS. In FIG. 1, an exhaust-side camshaft 11 serving as a first camshaft is provided for driving an exhaust valve 12, and a first journal 13 of the exhaust-side camshaft 11 is provided on a cylinder head 14. It is rotatably supported by the bearing portion 14a. An intake camshaft 16 serving as a second camshaft is provided for driving an intake valve 17, and a second journal 18 of the intake camshaft 16 is rotatably supported by a bearing portion 14 b of the cylinder head 14. Have been. A cam cap 20 is fastened and fixed to the cylinder head 14 with a fixing screw 21.
Both journals 1 are mounted on the bearing 20a of the cam cap 20.
3, 18 are supported from above.

A timing pulley 22 is fastened and fixed to a shaft end of the exhaust side camshaft 11 by a fixing screw 23. The timing belt 2 is attached to the timing pulley 22.
4, and transmits the rotation of a crankshaft (not shown) to the timing pulley 22. The timing pulley 22 is covered by a cover 25.

As shown in FIGS. 1 and 2, a VVT 30 is provided on the exhaust camshaft 11. VVT3
0 has a cover 31 surrounding the stator 31 and the stator 31 and the rotor 32. The stator 31 is fastened and fixed by a nut 34 so as not to rotate relative to the exhaust-side camshaft 11. Stator 31 and rotor 3
2 and a drive gear 35
Are mounted so as to be relatively rotatable. The drive gear 35, the rotor 32, and the cover 33 are integrally connected and fixed by a plurality of screws 36.

A driven gear 37 is provided on the intake side camshaft 16.
Is fixed. The driven gear 37 is meshed with the driving gear 35. The driving force of the exhaust side camshaft 11 includes a stator 31, a rotor 32, a driving gear 35, and a driven gear 3.
The power is transmitted to the intake camshaft 16 via the control valve 7. The exhaust valve 12 is driven by the rotation of the exhaust camshaft 11, and the intake valve 17 is driven by the rotation of the intake camshaft 16.

Next, the VVT 30 will be described in more detail. As shown in FIGS. 5 and 6, four first partitioning protrusions 38 are formed on the outer periphery of the stator 31 at equal intervals, and four second partitioning protrusions 39 are formed on the inner periphery of the rotor 32.
Are formed. The first partitioning protrusions 38 are arranged within the space between adjacent second partitioning protrusions 39, while the second partitioning protrusions 39 are disposed within the space between adjacent first partitioning protrusions 38. I have. In this state, the distal end side surface of the first partitioning projection 38 and the inner peripheral surface of the rotor 32 are in close contact, and the distal end side surface of the second partitioning projection 39 and the outer peripheral surface of the stator 31 are in close contact. . The rotor 32 is rotatable relative to the stator 31 so that a gap can be formed between the adjacent first section protrusion 38 and second section protrusion 39. In FIG. 5, the four gaps P1 are the first hydraulic chambers having the maximum volume, and in FIG. 6, the four gaps P2 are the second hydraulic chambers having the maximum volume.

The hydraulic pressure of the VVT 30 is controlled by the cam cap 20.
The control is performed by an oil control valve (OCV) 40 inside. The OCV 40 includes a spool 41 and a linear solenoid 42. The spool 41 is a skewer having a plurality of cylindrical valve bodies. The spool 41 is housed in a housing hole 43 formed in the cam cap 20 so as to be able to reciprocate in the axial direction. The spool 41 is disposed right above the VVT 30. The spool 41 is urged toward the linear solenoid 42 by the urging force of the compression spring 44. The spool 41 is urged in a direction against the compression spring 44 by the excitation of the linear solenoid 42. FIG. 5 shows a state where the supply current value is zero, and FIG. 6 shows a state where the supply current value is maximum.

In the cam cap 20, the storage hole 43
A first main hydraulic passage 45 is disposed substantially along the storage hole 43. The distal end side of the first main hydraulic passage 45 is connected to the storage hole 43. First main hydraulic passage 45
Is communicated with the inlet 46. The introduction port 46 is arranged at a position substantially at the same height as the OCV 40, and is connected to an oil supply pipe (not shown). An oil filter 47 is provided near the inlet 46 of the first main hydraulic passage 45. The inlet 46 is connected to an oil pan 49 via an oil pump 48. VV is located below the storage hole 43.
Second and third main hydraulic passages 6 for guiding oil to T30 side
3, 64 are provided. A discharge passage 65, which returns oil to the oil pan 49 adjacent to the two main hydraulic passages 63, 64,
66 are provided.

As shown in FIG. 2, the exhaust-side camshaft 1
Bearing portion 1 for supporting the first journal 13 from below
First and second hydraulic passages 51 and 52 are formed on the inner periphery of 4a. Third and fourth hydraulic passages 53 and 54 are formed on the inner periphery of the bearing portion 20a of the cam cap 20 that supports the journal 13 from above. As a result, a pair of annular hydraulic passages is formed around the journal 13 of the exhaust-side camshaft 11 by the first and third hydraulic passages 51 and 53 and the second and fourth hydraulic passages 52 and 54. As shown in FIG. 2, the third hydraulic passage 53 is provided with a fifth hydraulic passage 55 in the cam cap 20 and the main hydraulic passage 63.
Through the storage hole 43. The fourth hydraulic passage 54 is also the sixth hydraulic passage 5 in the cam cap 20.
6. The main hydraulic passage 64 communicates with the storage hole 43.

As shown in FIGS. 2, 5 and 6, a pair of annular hydraulic passages 57, 58
Are formed. The seventh hydraulic passage 57 communicates with the first and third hydraulic passages 51 and 53 via a ninth hydraulic passage 59 in the exhaust camshaft 11. The eighth hydraulic passage 58 communicates with the second and fourth hydraulic passages 52 and 54 via a tenth hydraulic passage 60 in the exhaust camshaft 11. The seventh hydraulic passage 57 communicates with the hydraulic chamber P1 via a passage 61 as shown in FIG. The eighth hydraulic passage 58 communicates with the hydraulic chamber P2 via a passage 62 as shown in FIG.

In such a configuration, the oil pump 48 supplies the oil in the oil pan 49 to the OCV 40 during operation of the engine. In the state of FIG. 5, the first main hydraulic passage 45 and the second main hydraulic passage 63 communicate with each other, and the third main hydraulic passage 64 and the discharge passage 66 communicate with each other. In this state, the oil in the oil pan 49 is supplied to the first main hydraulic passage 45, the second main hydraulic passage 63, the fifth hydraulic passage 55, and the first hydraulic passage 51 (the third hydraulic passage 51).
3) The power is supplied to the hydraulic chamber P1 via a ninth hydraulic passage 59, a seventh hydraulic passage 57, and a passage 61. The oil in the hydraulic chamber P2 is supplied to the passage 62, the eighth hydraulic passage 58, the tenth hydraulic passage 60, the second hydraulic passage 52 (the fourth hydraulic passage 54), the sixth hydraulic passage 56, and the third hydraulic passage 56. Main hydraulic passage 64
And returned to the oil pan 49 via the discharge passage 66.
Therefore, in FIG. 5, the rotor 32 is rotationally biased in the direction of the arrow R1. This rotational power is transmitted to the intake-side camshaft 16 via the drive gear 35 and the driven gear 37, and the opening / closing timing of the intake-side camshaft 16 is advanced.

In the state shown in FIG. 6, the first main hydraulic passage 4
The fifth main hydraulic passage 64 communicates with the fifth main hydraulic passage 64, and the second main hydraulic passage 63 communicates with the discharge passage 66. In this state, the oil in the oil pan 49 is supplied to the first main hydraulic passage 45, the third main hydraulic passage 64, the sixth hydraulic passage 56,
The hydraulic pressure is supplied to the hydraulic chamber P1 via a second hydraulic passage 52 (fourth hydraulic passage 54), a tenth hydraulic passage 60, an eighth hydraulic passage 58, and a passage 62. The oil in the hydraulic chamber P2 is supplied to the passage 61, the ninth hydraulic passage 59, the first hydraulic passage 5
The oil is returned to the oil pan 49 via the first (third hydraulic passage 53), the fifth hydraulic passage 55, the second main hydraulic passage 63, and the discharge passage 65. Accordingly, in FIG. 6, the rotor 32 is urged to rotate in the direction of arrow R2. This rotational power is transmitted via the drive gear 35 and the driven gear 37 to the intake camshaft 16.
And the opening / closing timing of the intake-side camshaft 16 is delayed.

With the above configuration, the above embodiment has the following effects. (1) The VVT 30 and the timing pulley 22 are mounted on the exhaust camshaft 11. Therefore, they do not interfere with each other. Therefore, there is no need to provide a margin in the axial direction so that the VVT 85 and the timing pulley 83 do not interfere with each other as in the first conventional example, and it is possible to prevent the engine from becoming larger.

(2) The drive gear 35 meshing with the driven gear 37 fixed to the intake camshaft 16 is mounted on the exhaust camshaft 11 inside the position of the timing pulley 22. Therefore, the total length of the intake camshaft 16 can be reduced as compared with the case where the driven gear 37 is disposed outside the timing pulley 22.

(3) The drive gear 35 meshing with the driven gear 37 fixed to the intake camshaft 16 is mounted on the exhaust camshaft 11 inside the position of the VVT 30. Therefore, the driven gear 37 is connected to the VVT 30
The overall length of the intake-side camshaft 16 can be shortened as compared with the case where it is arranged outside.

(4) In the above embodiment, the VVT 30 is mounted on the exhaust camshaft 11, and the variable camshaft whose phase is changed by the VVT 30 is the intake camshaft 16. That is, unlike the first conventional example, the variable camshaft does not need to have a two-axis structure of a fixed shaft and a rotating shaft, and there is no need to mount the connecting tube 87 unlike the second conventional example. That is, an increase in the size and weight of the cylinder head can be prevented. Further, since the connecting tube 87 is not required, the structure is simplified, and the problem seen in the second conventional example in which the exhaust camshaft 81 is supported via the connecting tube 87 is eliminated.

(5) In the above embodiment, the VVT 30, the drive gear 35 and the driven gear 37 are sealed in the cylinder head 14, so that noise of these members is less likely to leak outside.

(6) In the above embodiment, since the OCV 40 is built in the cam cap 20, there is no need to separately set the OCV 40 around the cylinder head 14.
Contributes to downsizing and weight reduction of the engine.

The present invention can be embodied in another embodiment as follows. In the following another embodiment, the same operation and effect as the above embodiment can be obtained. (1) In the above embodiment, the timing pulley 22 and the VV
T30 was mounted on the exhaust camshaft 11,
Conversely, it may be mounted on the intake side camshaft 16 and the exhaust side camshaft 11 may be a variable side camshaft.

(2) In the above embodiment, the drive gear 35 is disposed further inside the VVT 30. However, the drive gear 35 may be disposed between the VVT 30 and the timing pulley 22 (in the cylinder head 14).

(3) In the above embodiment, the VVT 30 is sealed inside the cylinder head 14, but may be exposed outside the cylinder head 14 like the timing pulley 22.

(4) In the above-described embodiment, the VVT 30 employs a rotary phase changing mechanism using the stator 31 and the rotor 32. However, a phase changing mechanism using a helical gear and a ring gear may be used.

(5) Although the OCV 40 in the VVT 30 of the above embodiment is provided inside the cam cap 20, the OCV 40 may be provided separately from the cam cap 20.

Other technical ideas grasped by the above embodiments will be described below together with their effects. (A) A hydraulic pressure supply means (OCV40 in the above embodiment) for supplying a hydraulic pressure to the valve timing changing means is formed in a cam cap covering the first camshaft.
3. The valve timing control device for an internal combustion engine according to any one of 3. Thus, there is no need to separately arrange only the hydraulic pressure supply means.

[0041]

According to the first aspect of the present invention, since the rotating body and the valve timing changing means are mounted on the first camshaft, there is no interference between the rotating body and the valve timing changing means. Further, since the second camshaft without the valve timing changing means is set to the variable side, the structure is simplified, and the conventional camshaft that occurs when the first camshaft to which the valve timing changing means is mounted is set to the variable side. The defect is eliminated.

According to the invention described in claim 2, according to claim 1
In addition to the effect of the invention described in the above, when the drive gear of the first camshaft and the driven gear of the second camshaft mesh,
The rotating body does not become an obstacle, and the second camshaft can be shortened. According to the third aspect of the invention, in addition to the effects of the first and second aspects of the invention, noise is reduced because the drive gear and the valve timing changing means are sealed in the cylinder head.

[Brief description of the drawings]

FIG. 1 is a plan sectional view of an embodiment of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG. 3;

FIG. 3 is a partially broken plan view.

FIG. 4 is a side view illustrating a schematic configuration of the same embodiment.

FIG. 5 is a sectional view showing a relationship between a valve timing mechanism and an oil control valve according to the same embodiment.

FIG. 6 is a sectional view showing the relationship between the valve timing mechanism and the oil control valve.

FIG. 7 is a side view illustrating a schematic configuration of a conventional embodiment.

FIG. 8 is a side view illustrating a schematic configuration of a conventional embodiment.

[Explanation of symbols]

11 Exhaust camshaft, 1st camshaft, 1
6 ... second intake camshaft, camshaft 14
... Cylinder head, 22 ... Rotary pulley, 35 ... Drive gear, 37 ... Driven gear, 30 ... Valve timing change mechanism (VV)
T).

 ──────────────────────────────────────────────────の Continuation of the front page (72) Inventor Masayasu Ushida 1-1-1 Showa-cho, Kariya-shi, Aichi Pref.

Claims (3)

[Claims] A pair of camshafts for driving intake and exhaust valves are rotatably mounted on a cylinder head of an internal combustion engine, and drive from a crankshaft of the internal combustion engine is transmitted to a first camshaft. A rotating body, a drive gear that transmits the rotation of the first camshaft to the second camshaft, and is rotatable relative to the first camshaft; A valve timing control device for an internal combustion engine, wherein a driven gear meshing with the driving gear is fixed to a second camshaft while a valve timing changing means for changing the timing is mounted on the first camshaft. . 2. The valve timing control device according to claim 1, wherein the rotating body is mounted near an axial end with respect to a mounting position of the drive gear and the valve timing changing unit. 3. The valve timing control device according to claim 2, wherein the rotating body is disposed outside a cylinder head, and the drive gear and the valve timing changing unit are disposed inside the cylinder head.