JPH11210420A - Variable valve system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To miniaturize and lighten a device, reduce rotational inertia, simplify a hydraulic fluid supply passage and improve assemblage by forming without using a spring a lock mechanism preventing the phase shift of a cam while an engine in a cam phase varying device is stopped so as to prevent occurrence of misfire when the engine is started. SOLUTION: When a vane 44 is rotated to the most phase lag position in a housing 30, a lock pin 70 is inserted in a lock hole 22b by applying hydraulic fluid from a phase lag side oil chamber to the base end part of a lock pin 70 through an oil passage 44d. When hydraulic fluid is applied from a phase advance side oil chamber to the end part of the lock pin 70 through an oil passage 44c, the lock pin 70 is released from the lock hole 22b so as to cancel lock.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable valve mechanism for variably adjusting the rotation phase of a camshaft relative to a rotation transmitting member that can rotate synchronously with a crankshaft of an internal combustion engine by hydraulic pressure. The vane type locks the vane member at the most retarded position when the vane member is rotated to the most retarded position by the supply of pressure oil, and releases the lock by supplying the pressure oil to the advance side oil chamber thereafter. The present invention relates to a cam phase changing device.

[0002]

2. Related Background Art A DOHC engine having a cam phase variable device mounted on an intake side camshaft has been put to practical use. The variable cam phase device variably adjusts the valve overlap period during which both the intake and exhaust valves of the engine are open to improve engine startability and engine output in the mid-high speed range. The two components are interposed between the drivingly connected cam sprocket and the camshaft so that the two components can rotate relative to each other and maintain a desired relative rotation position.

[0003] There is a hydraulic vane-type variable cam phase device. The hydraulic vane-type device includes a housing member rotatable with a cam sprocket, a vane housed in the housing member, and a camshaft. And a vane member that can rotate integrally with the vane member. The cam phase is changed by supplying and discharging pressure oil to and from an oil chamber formed between the vane and the housing member. While the hydraulic vane type cam phase variable device has an advantage that it can be manufactured relatively inexpensively, it has a disadvantage that the cam phase fluctuates when the engine is started as described below.

The variable cam phase device is disposed at the end of the camshaft, and its oil chamber is located above the engine. Therefore, when the operation of the oil pump is stopped along with the stop of the operation of the engine and the supply of the pressure oil from the oil pump to the oil chamber of the variable cam phase device is stopped, the pressure oil in the oil chamber flows into the cylinder head. The connection between the vane and the housing member via the pressure oil is released, and the vane can freely rotate within the housing member.

When the engine is started in such a state, for example, during the period from the opening of the cam to the maximum lift during the valve opening period of the cam, the vane is pushed by the housing member to rotate the camshaft, and the valve opening timing is reduced. It is on the retard side. However, during the period from the maximum lift to the closing of the valve, the camshaft is rotated by the rotation torque of the valve spring, and the vane rotates faster than the housing member, so that the valve closing timing is advanced.

For this reason, when a vane which is not constrained by pressure oil moves in the housing member, the cam phase changes. On the other hand, since the ignition timing is set to a fixed value suitable for starting the engine, if the cam phase fluctuates, the ignition timing becomes inappropriate, misfiring easily occurs, and the emission of unburned gas is accompanied. This is not preferable from the viewpoint of exhaust gas purification. As a countermeasure against oil leakage from the oil chamber after the engine is stopped,
Japanese Patent Application Laid-Open No. 121123 discloses a valve timing adjusting device in which a pilot check valve is provided in each of an oil path connecting a hydraulic pressure supply unit and a retard hydraulic chamber and an oil path connecting a hydraulic pressure supply unit and an advance hydraulic chamber. Proposed. This device is
Although useful for oil drainage while the engine is stopped, cam phase shift may occur when engine operation is stopped under certain conditions. For example, if the engine operation is stopped during the period from the maximum lift to the closing time during the opening period of the intake valve by the cam, the driving torque for promoting the cam rotation by the valve spring acts on the vane side via the cam shaft. The vane rotates in the advance direction while moving the oil in the retard hydraulic chamber to the advance hydraulic chamber through a slight clearance between the vane and the rotation transmitting member. On the other hand, the rotation transmission member side of the device immediately stops rotating due to frictional action in the crank system of the engine. As a result, the cam phase shifts to the advanced side, and misfire may occur at the next engine start.

Therefore, a valve timing adjusting device provided with a lock mechanism for preventing a cam phase shift due to a driving torque has been proposed in Japanese Patent Application Laid-Open No. 9-60508. The lock mechanism of the proposed device includes a stopper piston having a large-diameter portion accommodated in an accommodation hole formed in a vane of a vane rotor and a small-diameter portion fitted in a stopper hole formed in a front plate of a housing member. It has a spring that is installed and biases the piston toward the front plate, and a guide ring that is interposed between the small-diameter portion of the piston and the inner wall of the vane in the receiving hole. A hydraulic chamber communicating with the retard hydraulic chamber is formed in the vane rotor between the guide ring and the large-diameter portion of the piston, and an advanced hydraulic chamber communicates with the front plate between the stopper hole and the small-diameter portion of the piston. A hydraulic chamber is formed. The lock mechanism locks the vane rotor by fitting the piston into the stopper hole by the urging force of the spring when the pressure oil is not supplied to the two hydraulic chambers and the vane is at the most retarded position. When pressure oil is supplied to any of the chambers, the piston is released from the stopper hole to release the lock.

[0008]

The above lock mechanism is
Although it is possible to prevent phase shift due to cam drive torque,
In addition to the lock spring, it is necessary to provide two hydraulic chambers for unlocking, two systems of hydraulic oil supply systems to both hydraulic chambers, and a guide ring for separating the two hydraulic chambers. With the arrangement of the guide ring and the spring inside the vane, the length in the thickness direction of the vane is increased, and the vane is formed of an iron-based material in order to increase the mechanical strength of the vane in which a large-diameter receiving hole is formed. It needs to be made of a material. As a result, not only does the size of the device increase, but also the rotational inertia of the vane rotor increases, and the load on the rotation transmitting element that transmits the rotational force of the crankshaft to the housing member increases. When the rotation transmitting element is constituted by a belt and a back pressure release hole is provided to facilitate movement of the stopper piston in the accommodation hole, in order to prevent belt deterioration due to oil from the back pressure release hole. Although it is desirable that the back pressure release hole communicates with the inside of the cylinder head, the back pressure release hole and the pressurized oil supply system are congested and layout becomes difficult. Further, when a locking spring is used, the stopper piston must be pushed in against the urging force of the spring when assembling the device, and the assembling workability is deteriorated.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a lock mechanism for preventing a cam phase shift due to an oil spill when the engine is stopped and for preventing a misfire from occurring at the time of engine start without using a spring. It is an object of the present invention to provide a variable valve mechanism that reduces rotational inertia and simplifies a pressure oil supply path and that is excellent in assemblability.

[0010]

SUMMARY OF THE INVENTION A variable valve mechanism according to the present invention comprises a housing member rotatable integrally with a rotation transmitting member to which a rotational force is transmitted from a crankshaft of an internal combustion engine, and a housing member disposed in the housing member. A vane member having a vane portion and being rotatable integrally with the camshaft and rotatable relative to the housing member, and a vane member provided by hydraulic oil supply means to supply hydraulic oil to a retard side oil chamber between the vane portion and the housing member. A lock mechanism for fitting the movable body into the lock hole when the member rotates to the predetermined retard position, and releasing the movable body from the lock hole by supplying hydraulic pressure to the advance-side oil chamber between the vane portion and the housing member. And characterized in that:

In the variable valve mechanism having the above-described structure, the supply of the pressurized oil to the retard-side oil chamber causes the vane portion to rotate in the housing member, the vane member to rotate relative to the housing member, and one end of the hole to the other end. Pressure oil is supplied to one end of a movable body, for example, a lock pin, and the movable body is urged toward the lock hole. Therefore, when the vane member is rotated to the predetermined retard position, for example, the most retard position where the valve overlap amount is minimized, and the movable body is aligned with the lock hole, the movable body is fitted into the lock hole and the vane member is moved to the predetermined retard position. Locked in position. On the other hand, when the pressurized oil is supplied to the other end of the hole and, consequently, the other end of the movable body with the supply of the pressurized oil to the advance-side oil chamber, and the movable body is urged toward the anti-lock hole side, Is released from the lock hole and the lock is released. As described above, in the variable valve mechanism of the present invention, the urging means such as the spring for urging the movable body such as the lock pin and the stopper piston toward the lock hole side, and a plurality of hydraulic oil supply systems for unlocking Locking and unlocking of the vane member are performed without using the.

When the operation of the internal combustion engine is stopped in the locked state, the locked state is maintained even if oil escapes from the retard side oil chamber and the advance side oil chamber during the stop of the operation of the internal combustion engine. No cam phase shift occurs. Therefore, even when the internal combustion engine is started next time, this locked state is maintained, and occurrence of misfire at the time of starting is prevented.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a vane type cam phase changing device as a variable valve mechanism according to an embodiment of the present invention will be described. The cam phase variable device of the present embodiment is attached to the intake camshaft of the DOHC engine and variably controls the amount of overlap of the intake valve with the exhaust valve. In the following description, the configuration on the intake valve side will be mainly described. I do. However, this device can be arranged on both the exhaust side and the intake / exhaust side of the engine.

In FIG. 1, a cylinder head of a DOHC engine and a cam cap plate 2 disposed above the cylinder head are shown.
A cam journal 15 that rotatably supports the intake-side camshaft 10 is provided at a joint portion (indicated schematically by a two-dot chain line). The cam 4 is formed on the camshaft 10 so as to contact the intake valve via the rocker arm.
The intake valve opens and closes as the camshaft 10 rotates.

The crankshaft (not shown) of the engine is connected to a cam pulley or a cam sprocket (rotation transmitting member 20) on the intake side via a torque transmitting element (not shown) such as a belt or a chain. The rotational force transmitting element of the present embodiment is constituted by a toothed belt made of, for example, a synthetic resin in order to reduce the weight and cost, and the rotational transmitting member 20 is constituted by a cam pulley. The cam pulley 20 has a disc-shaped main body 22, a toothed flange 24 that meshes with a toothed belt, and a boss 26 that is fitted to an end of the camshaft 10. That is, the cam pulley 20 is arranged coaxially with the camshaft 10 and is rotatably supported by the camshaft 10 so as to rotate by receiving the torque of the crankshaft transmitted via the toothed belt. .

The cam phase changing device of the present embodiment also intends to reduce the rotational inertia, weight and external dimensions of each part of the device and to improve the rotational balance of the device, as will be described in detail later. In connection with this, on the outer peripheral side of the cam pulley main body 22, to reduce the rotational inertia and weight of the cam pulley 20,
For example, four slots 22a (FIG. 2) are formed. In FIG. 2, reference numeral 20a indicates a mark used for positioning the rotational phase of the camshaft 10 with respect to the crankshaft.

A ring-shaped oil seal 17 for preventing oil leakage to the outside of the engine is arranged between the boss 26 of the cam pulley 20 and the opposing peripheral surface of the cam journal 15. Oil used for lubrication around the camshaft 10 is returned into the engine through an oil passage 15c formed in the cam journal 15. The cam phase changing device is composed of, for example, four bolts 23 (FIG. 4) using the cam pulley main body 2.
A vane housing (accommodating member) 30 fixed to the outer end surface of the cam 2 and rotatable with the cam pulley 20;
A vane rotor (vane member) fixed to the end face of the camshaft 10 and rotatable integrally with the camshaft 10
40, and both elements 30, 40 are arranged coaxially with the camshaft 10 and the cam pulley 20. The vane housing 30 and the vane rotor 40 are formed by extruding a material made of a light alloy, for example, based on aluminum or the like, to reduce the weight and the rotational inertia. In such a variable cam phase device having a small rotational inertia, the load applied to the rotational force transmitting element connecting the crankshaft and the cam pulley 20 becomes small. Therefore, the rotational force transmitting element is connected to the belt as described above. Configurable. In the following, the elements 10, 20, 30, and 4 are related to the arrangement of the elements and the rotational balance in the variable cam phase device.
0 may be collectively referred to as a cam drive system.

The vane rotor 40 rotates integrally with the vane housing 30 while being drivingly connected to the vane housing 30 via pressure oil supplied between the vane rotor 30 and the vane housing 30. . The rotational force of the crankshaft is transmitted to the camshaft 10 via the cam pulley 20, the vane housing 30, and the vane rotor 40.

The cam pulley 20 has the boss portion 26 fitted to the camshaft 10 and is rotatable relative to the camshaft 10. In addition, the vane rotor 4
0 is rotatable within the housing 30 within a predetermined angle range of, for example, about 30 degrees with respect to the housing. When the vane rotor 40 rotates, the cam pulley 20
, The rotational phase of the camshaft 10 changes, and the amount of valve overlap between the intake valve and the exhaust valve changes. In the present embodiment, when the vane rotor 40 assumes the most retarded rotation position shown in FIG. 7, the valve overlap amount is reduced to substantially zero to improve the startability of the engine. The intake efficiency is improved by increasing the lap amount.

More specifically, the vane rotor 40 has a cylindrical main body 42 and, for example, four vanes 44 provided at equal angular intervals on the peripheral surface of the rotor main body 42 (FIG. 2). A pin hole 42b is formed on the cam shaft side end surface of the rotor main body 42, and a pin hole is formed on the facing end surface of the camshaft 10 in alignment with the pin hole 42b.
The mounting position of the vane rotor 40 with respect to the camshaft 10 is determined by the pins 8 arranged in both pin holes.

The vane 44 extends radially outward from the vane rotor main body 42. Each of the vanes 44 is formed in a tapered shape (substantially trapezoidal shape in the present embodiment) when viewed in a longitudinal section, whereby the weight of the vane 44 at the radially outer portion is reduced, and therefore, the rotational inertia of the vane 44 is reduced. It is greatly reduced. Further, each vane 44 has a symmetrical cross-sectional shape with respect to the longitudinal axis of the vane passing through the center of rotation of the vane rotor. The vane rotor 40 in which such tapered vanes 44 are provided at equal intervals in the circumferential direction has a small rotational inertia, and furthermore, the vane rotor rotation center and, consequently, the rotational balance of the cam drive systems 10, 20, 30, and 40 around the rotation axis. Abundant, rotational vibration is suppressed.

The vane housing 30 has a housing body 32 and a housing end wall 34. The housing body 32 has the same number (for example, four) of peripheral wall portions 32 as the number of vanes.
a, a pair of partition walls 32b, 32c extend inward in the vane rotor radial direction from both edges of each housing peripheral wall portion 32a in parallel with each other. The inner surface of the partition 32b is arranged symmetrically to the partition 32b with respect to a virtual plane passing through the center of rotation of the vane rotor and orthogonal to the partition 32b.
It is flush with the inner surface of c. The inner end of the partition 32b is connected to the partition 3b adjacent to the partition 32b in the circumferential direction of the vane rotor.
It is connected to the inner end of 2c (hereinafter, the connecting portion of adjacent partition walls is referred to as partition connecting portion 32d). Housing 30
The inner peripheral surface of the partition connecting portion 32d is formed in an arc shape in a vertical section and is in sliding contact with the outer peripheral surface of the vane rotor main portion 42, and rotatably supports the vane rotor 40. A bolt hole 2 through which the bolt 23 is inserted is formed in the partition joint 32d.
3a are formed.

Since the vane 44 has a tapered shape as described above, the circumferential length of the housing peripheral wall portion 32a can be reduced while the cam phase variable range is required. For this reason, in order to reduce the rotational inertia of the housing 30, the radially outer portion of the housing 30 can be thinned around the partition connecting portion 32d. That is, the outer surface of the thinned-out partition coupling portion 32d is located radially inward of the housing peripheral wall portion 32a, for example, the slot 2 of the cam pulley 22.
2a extends along the defining surface.

Each pair of partition walls 32 of the vane housing 30
b and 32c define a vane accommodating chamber for accommodating the vane 44 in cooperation with the housing end wall 34 and the cam pulley main body 22. In other words, the cam pulley main body 22 of the present embodiment constitutes a housing member together with the housing elements 32 and 34. A seal 49 is provided between the distal end peripheral surface of the vane 44 and the inner peripheral surface of the housing peripheral wall portion 32a,
The seal 49 and the vane 44 divide the vane accommodating chamber into two, an advanced oil chamber 47 and a retard oil chamber 48. That is, the vane housing 30 and the vane rotor 40
And four pairs of oil chambers 47 and 48 with each vane 44 interposed therebetween.
Is defined. By supplying pressure oil to one of the oil chambers 47 and 48, the vane rotor 40 is rotated in the housing 30.

In the present embodiment, as described later, an oil pump normally provided in an engine is used as a pressure oil supply source. In such a case, there is a restriction on the increase in the vane rotor rotational force due to the increase in oil pressure. Therefore, in the present embodiment, the number of vanes is relatively large, for example, four, so that the total pressure receiving surface of the entire vane is widened, and the rotational force of the vane rotor generated by the supply and discharge of the pressure oil is increased.

The vane housing 30 and the vane rotor 40 according to the present embodiment are obtained by extrusion molding as described above, and the opposing surfaces of the two elements 30, 40 are cut using a broaching machine or the like as necessary. You. By providing the pair of partition walls 32b and 32c in parallel with each other as described above and providing the inner surfaces of the pair of partition walls 32c and 32b on the same plane as the inner surfaces of the pair of partition walls 32c and 32b opposed in the diametrical direction of the vane rotor, broaching is performed. And the processing accuracy is improved, and the inspection of the processed surface is facilitated. For example, using a test jig 81 schematically shown by a two-dot chain line in FIG. The processing surface of two partitions can be inspected at a time.

Next, the supply and discharge of pressure oil to and from the oil chambers 47 and 48 will be described. As shown in FIG. 1, the cam journal 15 is formed with first and second oil passages 15 a and 15 b extending substantially perpendicular to the longitudinal axis of the cam shaft 10. Outer ends of the oil passages 15a and 15b communicate with first and second outlet ports 51 and 52 of an oil control valve (OCV) 50, respectively. OCV50
The first inlet port 53 is connected to an oil supply pipe 63 communicating with the discharge side of an oil pump 62 that pressurizes oil pumped from an oil tank 60, and the second inlet port 54 is connected to a return pipe 64. As described later, the first oil passage 15
a is in communication with the retard side oil chamber 47, and the OCV 50 is
The first inlet port 53 and the first outlet port 51 communicate with each other at a switching position (retard position) 50a shown in FIG.
When the inlet port 54 and the second outlet port 52 communicate with each other, the pressure oil from the oil pump 62 is supplied to the retard side oil chamber 48. On the other hand, the OCV 50 takes another switching position (advance angle position) 50b, and the first inlet port 53 and the second outlet port 52 communicate with each other.
When the first outlet port 51 and the fourth outlet port 51 communicate with each other, pressure oil is supplied to the advance-side oil chamber 47. The OCV 50 is duty-controlled by, for example, an electronic control unit (not shown) in accordance with the engine speed to control the supply and discharge of pressure oil to and from the oil chambers 47 and 48, and to variably control the rotational phase of the cam pulley 20 with respect to the camshaft 10. I am trying to do it. Also, the OCV 50 takes the neutral position 50c, and the inlet port 5
When the communication between the ports 3 and 54 and the outlet ports 51 and 52 is interrupted, the rotational phase is maintained. That is, OCV
Constitutes a hydraulic supply means for rotating the vane rotor 40 to the retard side or the advance side by hydraulic pressure as needed together with the oil pump 62 and the like.

The inner ends of the first and second oil passages 15a and 15b formed on the cam journal 15 and constituting a part of the pressure oil supply / discharge passage are formed by the first and second oil passages formed on the peripheral surface of the cam shaft 10. The two annular grooves 11a and 11b are open.
The camshaft 10 has first radial holes 12 extending from the first annular groove 11a to a position short of the camshaft axis.
a, and a second radial hole 12b extending from the second annular groove 11b to the camshaft axis is formed in the camshaft radial direction. The number of the first radial holes 12a is equal to the number of the vanes. The hole 12a communicates with the first annular groove 11a and the hole 12b communicates with the second annular groove 11b when the camshaft 10 is in any rotational position. In the camshaft 10, first and second extending from inner ends of the holes 12a and 12b to the camshaft end surface, respectively.
The longitudinal holes 13a, 13b are formed in the camshaft axial direction. One second longitudinal hole 13b is provided on the camshaft axis, and the same number of the first longitudinal holes 13a as the number of vanes is provided at a radial position offset from the camshaft axis.

The second longitudinal hole 13b is a stepped hole and has a small diameter portion communicating with the second radial hole 12b and a large diameter portion into which the hollow bolt 14 with a hexagonal hole is screwed. I have. The hollow bolt 14 is disposed in a stepped through hole 42a formed coaxially with the vane rotor main body 42, and the head of the hollow bolt 14 is accommodated in a large diameter portion of the stepped through hole 42a. The hollow portion 14a of the hollow bolt 14 is formed by the inner peripheral surface of the vane rotor main portion 42 (the surface on which the stepped through-hole 42a is formed) and the hexagon socket head bolt 36 screwed into the screw hole 35 at the center of the housing end wall 34. It communicates with an oil passage 41 having a U-shaped cross section defined by the inner end surface and the outer surface of the head of the hollow bolt 14.

In connection with the pressure oil supply / discharge path to the oil chambers 47 and 48, in the vane rotor 40, the rotor main body 42 has four short holes aligned with the four first longitudinal holes 13 a of the camshaft 10. First longitudinal holes 45a are formed in the axial direction of the vane rotor, and four first radial holes 46a are formed from the respective holes 45a and extend outward in the radial direction of the vane rotor. The outer end of the hole 46a is open to the outer peripheral surface of the rotor main body 42 near the root of the vane 44 and communicates with the retard-side oil chamber 48. A second radial hole 46b is formed in the vane rotor main body 42 in the radial direction of the vane rotor at the vane rotor thickness direction position offset toward the camshaft side with respect to the first radial hole 46a. The inner end of the hole 46 b has the rotor main body 4.
The second stepped through hole 42 a is opened at the large diameter portion, and the outer end is opened at the outer peripheral surface of the rotor main body 42 near the root of the vane 44 and communicates with the advance side oil chamber 47.

The above-mentioned annular groove, radial hole and longitudinal hole constitute an oil passage connecting the oil passage 15a or 15b with the oil chamber 48 or 47. As is clear from FIG. 2, the four first radial holes 46a that face each other in the vane rotor diameter direction extend on the same straight line. That is, the pair of holes 46a are provided on one straight line passing through the vane rotor rotation center, and the other pair of holes 46a are provided on another straight line passing through the vane rotor rotation center and orthogonal to the above-described straight line. According to such a hole arrangement, a pair of holes 46a to be arranged on the same straight line can be simultaneously formed by a single hole processing to reduce the processing cost. Also, each pair of holes 4
6a are arranged symmetrically with respect to the center of rotation of the vane rotor 40 (the axis of rotation of the cam drive system).
By forming 6a in the vane rotor 40, the rotational balance of the vane rotor 40 with respect to the rotational center of the vane rotor (the rotational balance of the cam drive system) is not impaired.

The variable cam phase device has a lock mechanism for locking the vane 44 at the most retarded rotation position in order to minimize the amount of overlap between the intake valve and the exhaust valve (eg, zero). . As shown in FIGS. 2 and 3, the lock mechanism of the present embodiment has the same number (for example, four) of lock pins (movable bodies) 70 as the number of vanes. Each lock pin 70 is movably arranged in a lock pin hole 44a formed through each vane 44 in the vane thickness direction.

As shown in FIG. 5, the lock pin 70 moves toward the cam pulley main portion 22 (lock release direction) by supplying the pressurized oil to the advance-side oil chamber 47, while moving to the retard-side oil chamber 48. Is moved toward the housing end wall 34 (locking direction) by the supply of pressure oil. Then, when the lock pin 70 moves to the vicinity of the most retarded rotation position, the tip 70 a of the lock pin 70 on the cam pulley main body side becomes
The lock pin 70 is locked by being fitted into a lock hole 22b formed on the opposite end face of the cam pulley main body 22.

In this locked state, the vane housing 3
The rotational torque applied to the vane rotor 40 from zero is shared by the four lock pins 70. At this time, the lock pin 70 is made of, for example, an iron-based material so as to withstand the shearing force applied to the lock pin 70. In this case, when it is necessary to move the lock pin 70 in the lock pin hole 44a with the cam phase variable device alone, this can be performed using a magnet.

This lock mechanism does not use any special urging means, such as a spring, for urging the lock pin 70 toward the lock hole 22b, except for supplying pressure oil to the retard side oil chamber 48. . Since the spring for urging the lock pin is not necessary, there is no need to form a spring accommodating space in the lock pin 70, and the lock pin length can be shortened by that much, and therefore, the vane 44 in which the lock pin hole 44a is formed. (Vane rotor 40) can be reduced in thickness. For this reason, the weight and rotational inertia of the vane rotor 40 can be reduced, and the outer dimensions of the entire cam phase variable device can be reduced.
Also, since it is not necessary to incorporate a spring when assembling the variable cam phase device, assembly of the device is simplified. Further, there is no need to provide a breathing hole (oil passage) for removing the back pressure applied to the spring in order to smooth the compression operation of the spring, and the vane 44 can be easily manufactured. Further, since no oil is discharged from the breathing hole, a belt which may be deteriorated by the oil can be used as the rotational force transmitting element.

A first oil passage 44c is formed on the end face of each vane 44 on the cam pulley main body 22 side for applying pressure oil from the advance side oil chamber 47 to the lock pin 70. The first oil passage 44c extends outward in the radial direction of the vane rotor from the lock pin hole 44a when viewed in the cross section in the thickness direction of the vane rotor (FIG. 3), and extends from the lock pin hole 44a in the longitudinal direction in the vane rotor when viewed in the cross section in the vane rotor (FIG. 2). It extends obliquely outward with respect to the axis and opens to the advance-side oil chamber 47. Advance side oil chamber 4
7 is applied to the pressure receiving surface (not shown in detail) of the distal end portion 70a of the lock pin 70 on the side of the cam pulley main body 22 through the first oil passage 44c, and the lock pin 70 is released. Acts to move in the unlocking direction along the lock pin longitudinal axis.

A second oil passage 44d is formed on the end surface of each vane 44 on the housing end wall 34 side to apply pressure oil from the retard chamber oil chamber 48 to the lock pin 70. The second oil passage 44d extends outward from the lock pin hole 44a in the vane rotor radial direction as viewed in a cross section in the vane rotor thickness direction (FIG. 3), and extends from the lock pin hole 44a in the vane longitudinal direction as viewed in the vane rotor cross section (FIG. 2). It extends obliquely outward with respect to the axis and in a direction opposite to the first oil passage 44 c and opens to the retard-side oil chamber 48. The pressure oil for locking from the retard side oil chamber 48 is applied to the pressure receiving surface (not shown in detail) of the base end 70b of the lock pin 70 on the housing end wall 34 side via the second oil passage 44d. , And acts to move the lock pin 70 in the lock direction along the lock pin longitudinal axis. If the lock pin 70 is in the vane rotation position aligned with the lock hole 22b (FIG. 7), the pressure oil supplied from the retard side oil chamber 48 is received, and the tip 70a of the lock pin 70 is inserted into the lock hole 22b. It will fit (FIGS. 6 and 7).

As described above, the lock pin hole 44a and the oil passages 44c, 44d extend in the vane thickness direction, that is, in the camshaft axis direction. Therefore, the vane rotor 40
When die cutting in the cam axis direction, these elements 44a,
44c and 44d can be formed at the same time, and finishing is performed as necessary. The four lock pin holes 44a are provided at equal angular intervals on the same circumference with respect to the center of rotation of the vane rotor, and are provided on the longitudinal axis of the vane. In other words, ones of the four lock pin holes 44a that face each other in the diametrical direction of the vane rotor are arranged symmetrically with respect to the center of rotation of the vane rotor. Therefore, the lock pins 70 housed in the lock pin holes 44a are also arranged symmetrically with respect to the center of rotation of the vane rotor. The above-mentioned lock hole 22b, oil passages 44c and 44d
Also, with respect to the vane rotor, those that face each other in the radial direction of the vane rotor are arranged symmetrically with respect to the center of rotation of the vane rotor.

As described above, the various elements of the lock mechanism are preferably provided symmetrically with respect to the center of rotation of the rotor vane including the oil passage, or a plurality of the same elements are arranged at least on the same circumference with respect to the center of rotation of the rotor vane and mutually. By providing them at equal angular intervals, deterioration of the rotation balance of the vane rotor 40 with respect to the vane rotor rotation center (the rotation axis of the cam drive system) due to the arrangement of the lock mechanism can be avoided.

In the above-described lock mechanism arrangement, one of the lock mechanisms facing each other in the diametrical direction of the vane rotor can be considered to function as balance means for the other lock mechanism. That is, if a lock mechanism is provided for one vane, the rotational balance of the vane rotor 40 is degraded by that amount. However, such a lock mechanism is provided by providing a lock mechanism of the same configuration to this vane and another vane facing the vane rotor in the radial direction. The poor rotation balance is compensated. In other words, when the lock mechanism is not provided on all the vanes, the vane provided with the lock mechanism and the vane arranged in the vane rotor diametrical direction have an operation equivalent to the lock mechanism on the rotational balance. By providing the rotation balance means, it is possible to compensate for deterioration of the rotation balance due to the arrangement of the lock mechanism. In a broader sense, the deterioration of the rotational balance caused by providing a lock mechanism on a certain vane can be compensated by providing rotational balance means on one or more other vanes. For example, when a lock mechanism is provided on one of the three vanes, the balance means is formed on the remaining two vanes. The rotation balance means
This can be realized by removing the thickness of the vane and adding an additional weight to the vane at a portion corresponding to the lock mechanism forming portion.

As described above, the lock mechanism of the present embodiment is provided so as to perform a lock operation when the vane 44 takes the most retarded rotation position. However, in practice, the lock hole 22b is formed so that its longitudinal axis coincides with a position where the vane 44 is slightly advanced to the advanced side from the most retarded side rotational position (FIG. 11). . On the other hand, by supplying the hydraulic pressure to the retard side oil chamber 48, the vane 44 is moved to the most retard side rotational position (FIG. 11) or a position immediately before the pivot position (FIG. 12).
Even when the lock pin tip 70a is turned up to the maximum delay position, the peripheral surface of the lock pin tip 70a has a tapered taper so that the lock pin tip 70a smoothly fits into the lock hole 22b provided slightly before the most retarded position. The peripheral surface of the lock hole 22b is also provided with a taper that tapers toward the bottom of the lock hole.

By setting the formation position of the lock hole 22b and the shapes of the lock pin tip portion 70a and the lock hole 22b as described above, during the locking operation of the lock mechanism, the lock pin 70 and the lock hole 22b are aligned. The vane 44 is locked at the lock position slightly advanced from the most retarded rotation position. As a result, in the lock operation completed state, a clearance is provided between the opposing surfaces of the vane 44 and the vane housing partition wall 32b. According to such a configuration, the lock hole 22b is formed at a position corresponding to the most retarded rotation position of the vane 44 so that the vane 44 comes into close contact with the vane housing partition wall 32b when the lock operation is completed. As compared with the above, the allowable processing error for the lock hole forming position and the vane and the vane housing partition can be set to a large value, the processing time and the processing cost can be reduced, and the hydraulic pressure from the advance side oil chamber 47 at the time of unlocking can be reduced. Start-up characteristics of the lock mechanism with respect to supply (lock pin 7 from lock hole 22b)
0 is easily removed). Also, when starting the engine,
The hitting sound due to the collision between the vane 44 and the housing 30 is prevented.

In this embodiment, the lock pin tip 70a
And the peripheral surface of the cam pulley main portion 22 are crowned. More specifically, the lock pin distal end portion 70a is formed in an outer shape (composite curved surface) such that its diameter decreases toward the lock pin distal end surface side and the lock pin diameter reduction rate increases toward the lock pin distal end surface side. . In other words, the peripheral surface of the lock pin distal end portion 70a is formed in a compound arc shape having a smaller curvature toward the lock pin distal end side when viewed in a longitudinal section (FIG. 8).
On the other hand, the peripheral surface of the lock hole 22b is formed in an arc shape that is outwardly convex and has a small curvature on the lock hole bottom surface side, and is formed in an arc shape that is outwardly concave and has a slightly large curvature on the lock hole opening surface side. I have.

According to the configuration in which the above-described crowning is provided on the peripheral surface of the lock pin tip portion 70a and the peripheral surface of the lock hole 22b, a machining error in the lock pin 70, the lock pin hole 44a, or the lock hole 22b is caused. Then, even when the axis of the lock pin hole 44a or the lock pin 70 does not exactly match the axis of the lock hole 22b, in the locked state (FIG. 9), the lock pin tip portion 70a and the lock hole 2
2b come into surface contact or line contact with each other.
Therefore, wear of the lock pin 70 and the lock hole forming portion of the cam pulley main body 22 due to the point contact between the lock pin tip portion 70a and the lock hole 22b is prevented. The above-described crowning may be applied to either the peripheral surface of the lock pin tip portion 70a or the peripheral surface of the cam pulley main body 22.

The operation of the variable cam phase device having the above configuration will be described below. During engine operation, the engine rotation speed is almost constant and the current cam phase (overlap amount of intake and exhaust valves)
Is appropriate, the oil control valve 50 is held at the neutral position 50c where the communication between the inlet ports 53 and 54 and the outlet ports 51 and 52 is cut off. In this case, the supply and discharge of the pressure oil to the advance side and the retard side oil chambers 47 and 48 are not performed, and the vane 44 of the cam phase variable device
It is immovably restrained by the oil filled in 7,48.
As a result, the cam pulley 20, the vane housing 30, the vane rotor 40, and the camshaft 10 rotate in synchronization with the rotation of the crankshaft while the relative rotational position between the vane housing 30 and the vane rotor 40 is fixed and the cam phase is maintained. Then, the intake valve is opened and closed by the cam 4 of the camshaft 10. As described above, each part of the vane housing 30 and the vane rotor 40 is configured in consideration of the rotational balance with respect to the vane rotor rotation center, and therefore, the rotational vibration caused by the rotation of the elements 30 and 40 is sufficiently suppressed.

Thereafter, when the engine speed rises, the oil control valve 50 connects the first inlet port 53 and the second outlet port 52 with each other and the second inlet port 5
4 is switched to the advanced position 50b where the first outlet port 51 communicates. As a result, the pressure oil from the oil pump 62 is hollow through the second oil passage 15b of the cam journal 15 and the second annular groove 11b, the second radial hole 12b, and the second longitudinal hole 13b of the camshaft 10. The fluid flows into the hollow portion 14a of the bolt 14, and further through the oil passage 41 and the second radial hole 46b of the vane rotor main body 42, the advance side oil chamber 4
7 is supplied. By supplying the pressurized oil to the oil chamber 47, an urging force acts on the vane 44 in the advancing direction (the side of the housing partition 32 c), and the vane 44 discharges the oil in the retarding-side oil chamber 48 while the vane 44 It moves in the advance direction in the vane accommodation room. As a result, the vane rotor 40 rotates relative to the housing 30 in the advance angle direction while rotating together with the vane housing 30, and the cam phase is advanced.

During the movement of the vane 44 in the advance direction, the oil in the retard-side oil chamber 48 is supplied to the camshaft 10 through the first radial hole 46a and the first longitudinal hole 45a of the vane rotor main body 42. Flows into the first longitudinal hole 13a and then
The oil is discharged into the cylinder head through the first radial hole 12a and the first annular groove 11a of the camshaft 10, the first oil passage 15a of the cam journal 15, and the oil control valve 50, and returns to the oil tank 60.

When the pressurized oil is supplied to the advance side oil chamber 47 as described above, the lock pin tip from the oil chamber 47 through the first oil passage 44c on the end surface of the vane 44 on the cam pulley main body 22 side. Pressure oil is supplied to the pressure receiving surface 70a to urge the lock pin 70 in the lock release direction (lock pin base end 70b side). At this time, since the lock pin 70 is already in the unlocked state, this unlocked state is maintained (FIGS. 2 and 10).

After that, when the engine speed decreases, the oil control valve 50 connects the first inlet port 53 and the first outlet port 51 to each other and the second inlet port 5
4 is switched to the retard position 50a shown in FIG. 1 where the second outlet port 52 and the second outlet port 52 communicate with each other. As a result, the pressure oil from the oil pump 62 is supplied to the retard-side oil chamber 48 by following the path corresponding to the oil discharge path when the oil control valve 50 is in the advanced position in the reverse direction. By supplying the pressure oil to the oil chamber 48, the vane 44 is retarded in the retard direction (the housing partition 32b).
Side), the vane 44 is advanced to the advance side oil chamber 47.
It moves in the retard direction in the vane housing chamber of the vane housing 30 while discharging the oil inside. As a result, the vane rotor 4
0 rotates with the vane housing 30 in the retard direction with respect to the housing 30, and the cam phase is retarded. Oil is discharged from the advance side oil chamber 47 by following a path corresponding to the pressure oil supply path when the oil control valve 50 is at the advance position in the reverse direction, and the pressure oil returns to the oil tank 60.

Also, when supplying the pressure oil to the retard side oil chamber 48, the second oil passage 44 in the end face of the vane 44 on the housing end wall 34 side is provided.
Pressure oil is supplied from the oil chamber 48 to the pressure receiving surface of the lock pin base end portion 70b through the oil chamber d to urge the lock pin 70 in the lock direction (lock pin tip end portion 70a side), but the engine is idling. If not, the lock pin 70 is not aligned with the lock hole 22b, and the lock pin 70 is
It does not fit into 2b. That is, the lock pin 70
Is maintained in an unlocked state in which the tip portion 70a is in contact with the cam pulley main portion 22 (FIGS. 2 and 1).
0).

Immediately before stopping the operation of the engine, the engine is operating at idle. During this idle operation,
Pressure oil is supplied from the oil pump 62 to the retard side oil chamber 48 via the oil control valve 50 at the retard position shown in FIG. 1 so that the vane 44 rotates to the most retard position in the vane storage chamber. You. As a result, the lock pin 70 is substantially aligned with the lock hole 22b (shown by a two-dot chain line in FIGS. 11 and 12). At this time, since the pressure oil is supplied from the oil chamber 48 to the pressure receiving surface of the lock pin base end portion 70b through the second oil passage 44d of the vane 44, the lock pin 70 is urged in the locking direction. The lock pin 70 has a lock hole 22b.
The inner oil and the oil in the first oil passage 44c of the vane 44 are fitted into the lock hole 22b while being discharged along the oil discharge path from the retard side oil chamber 48 (FIG. 9). As a result, the vane 44 is locked at the most retarded position (FIG. 7). The fitting of the lock pin 70 into the lock hole 22b is performed by the two elements 22b,
Smoothly performed by the centering action of FIG.
2).

While the engine is stopped, the lock pin 70 remains fitted in the lock hole 22b (FIG. 7).
And FIG. 9), the vane 44 is locked at the most retarded position. While the engine is stopped, the oil in the advance-side and retard-side oil chambers 47 and 48 located above the cam journal 15 escapes into the cylinder head, but the locked state of the vane 44 is maintained.

At the next start of the engine, the vane 44 is locked at the most retarded position suitable for starting the engine, and the engine starts smoothly without occurrence of misfire. Further, since a slight clearance is provided between the locked vane 44 and the housing partition 32b, the vane 44 and the housing partition 32b may be connected to each other even if a positive or negative torque is applied to the cam from the intake valve side when the engine is started. There is no collision and no hitting sound is generated.

The variable valve mechanism according to the present invention is not limited to the above embodiment, but can be variously modified. For example, in the above-described embodiment, the cam phase variable device having four vanes has been described, but the number of vanes is not limited to four. FIG. 14 illustrates a two-vane apparatus. This device has substantially the same configuration as that of the above-described embodiment except that the number of vanes 44 is two. Elements corresponding to those of the above-described embodiment are denoted by the same reference numerals in FIG. 14, and description thereof will be omitted.

When the engine is started while the lock mechanism is locked, a drive torque is applied to the lock mechanism from the intake valve or the exhaust valve via the camshaft. 8-1211
The pilot check valve proposed in Japanese Patent Publication No. 23 may be incorporated in the device of the present invention. In this case, one of the pilot check valves is connected to the oil passage 1 of the cam journal 15.
The oil passage 5a and the retard side oil chamber 48 communicate with each other, and are arranged, for example, in the oil passage 46a of the vane 44. The other pilot check valve is disposed in an oil path that connects the oil path 15b and the advance-side oil chamber 47, for example, an oil path 46b.

[0056]

The variable valve mechanism according to the present invention has a housing member rotatable integrally with a rotation transmitting member to which a rotational force is transmitted from a crankshaft of an internal combustion engine, and a vane disposed in the housing member. A vane member rotatable integrally with the camshaft and rotatable relative to the housing member; and a movable member when the vane member rotates to a predetermined retard position by supplying hydraulic oil from the hydraulic pressure supply means to the retard side oil chamber. And a lock mechanism for releasing the movable body from the lock hole by supplying hydraulic pressure to the advance-side oil chamber while fitting the oil into the lock hole, so that the retard-side oil chamber and the advance-side oil Even if oil escapes from the chamber, even when the internal combustion engine is started next time, the locked state is maintained and the cam phase is not shifted, so that the occurrence of misfire at the start can be reliably prevented. Further, the lock mechanism of the present invention does not use a biasing means such as a spring for biasing a movable body including a lock pin and a stopper piston toward the lock hole, and a plurality of pressure oil supply systems for unlocking. In addition, since the lock and unlock of the vane member can be performed, the length of the movable body and thus the thickness of the vane can be reduced, and the variable valve mechanism can be reduced in size and weight. Also,
There is no need to form a large-diameter accommodation hole in the vane, the pressure oil supply system for unlocking is simple, and there is no need for a back pressure release hole to facilitate the movement of the movable body in the hole. As a result, the strength requirements for the vane member are relaxed, and the weight can be further reduced by, for example, making the vane member made of a light alloy. Further, the manufacture of the vane member becomes easy. Further, since it is not necessary to incorporate the urging means, the assembly can be easily performed. Further, since the rotational inertia is small, the load applied to the element for transmitting the rotational force from the crankshaft to the rotation transmitting member is reduced, and the element can be configured by a belt or the like.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a variable cam phase device according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of the variable cam phase device taken along the line II-II in FIG. 1 or FIG.

FIG. 3 is a cross-sectional view of the variable cam phase device in the unlocked state, taken along line III-III of FIG. 4;

FIG. 4 is an end view of the variable cam phase device.

FIG. 5 is a sectional view taken along the line VV in FIG. 2;

FIG. 6 is a cross-sectional view of the variable cam phase device.

FIG. 7 is a sectional view taken along the line VII-VII of FIG. 6, showing the cam phase variable device in a locked state;

FIG. 8 is an enlarged partial cross-sectional view showing the shapes of a lock pin tip and a lock hole.

FIG. 9 is an enlarged partial sectional view showing the lock pin in a locked state.

FIG. 10 is an enlarged partial sectional view showing a lock pin in an unlocked state.

FIG. 11 is an enlarged partial cross-sectional view showing a lock pin formation position and a centering action of the lock pin and the lock hole.

FIG. 12 is an enlarged partial cross-sectional view showing a centering action of a lock pin and a lock hole.

FIG. 13 is a plan view showing easiness of inspection of a housing of the variable cam phase device.

FIG. 14 is a cross-sectional view of a cam phase changing device according to a modification of the present invention.

[Explanation of symbols]

4 Cam 10 Camshaft 11a, 11b, 12a, 12b, 13a, 13b, 1
4a, 15a, 15b, 41, 45a, 46a, 46b
Oil passage 20 Cam pulley 22b Lock hole 30 Vane housing 40 Vane rotor 44 Vane 44a Lock pin hole 44c, 44d Oil passage 47 Advance oil chamber 48 Delay oil chamber 50 Oil control valve 62 Oil pump 70 Lock pin

Claims (1)

[Claims] 1. A housing member rotatable integrally with a rotation transmitting member to which a rotational force is transmitted from a crankshaft of an internal combustion engine, a retard-side oil chamber disposed between the housing member and the housing member, and A camshaft having a vane portion defining an advance-side oil chamber, and having a cam portion for opening and closing one of an intake valve and an exhaust valve of the internal combustion engine; Hydraulic supply for supplying a hydraulic pressure to the rotatable vane member and the retard-side oil chamber or the advance-side oil chamber to cause the vane member to rotate relatively to the retard side or the advance side with respect to the rotation transmitting member. Means, when the vane member is relatively rotated to a predetermined retard position by the supply of pressurized oil to the retard-side oil chamber, the movable member disposed in the hole formed in the vane member or the accommodation member is the accommodation member or Lock formed on the vane member And a lock mechanism that fits into the hole and releases the movable body from the lock hole by supplying hydraulic pressure to the advance side oil chamber.