JP3349206B2 - Engine valve timing control device - Google Patents

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 an engine in which a camshaft having a tapered cam is moved in an axial direction to vary a valve lift.

[0002]

2. Description of the Related Art Conventionally, as a valve timing control device of the above-mentioned engine, for example, Japanese Patent Publication No. 58-3860
There is an apparatus described in Japanese Patent Publication No. That is, as shown in FIG. 10, the camshaft 10 which rotates in synchronization with the engine
1, a tapered cam 102 is integrally formed, a rocking cam 104 driven by the tapered cam 102 and rocking about a rocking camshaft 103, and a suction / exhaust valve 105 is lifted following the rocking cam 104. Rocker arm 10
6 and the above-described tapered cam 102 and swing cam 104
And a drive means for relatively moving the oscillating cam 104 in the axial direction is provided, and the initial phase of the oscillating cam 104 is changed according to the operation state to change the valve timing. Is a valve timing control device for an engine configured to variably control the valve timing.

Here, since the above-mentioned tapered cam 102 is formed in a tapered shape in the axial direction of the camshaft 101, thrust fluctuation occurs in the tapered cam 102 and the camshaft 101. That is, when the intake / exhaust valve 105 is opened by the rocker arm 106 described above, the reaction force of the valve spring 107 causes the tapered cam 102 to move through the respective elements.
And the intake and exhaust valve 105 by the rocker arm 106
When the valve is closed, the reaction force of the valve spring 107 becomes zero.
Thrust fluctuations are repeatedly applied to the camshaft 101 from zero to the maximum and from the maximum to zero via the 02 tapered surface.

Therefore, instead of the driving means for relatively moving the swing cam 104 in the axial direction, a hydraulic actuator as a camshaft moving means for moving the camshaft 101 in the axial direction to vary the valve lift. If the provided, between the piston rod end and the hydraulic actuator of the camshaft 101, with the rotation of the camshaft
There Ri by the thrust variations due to the taper of the cam slapping sound there has been a problem that occurs.

[0005]

THE INVENTION Problems to be Solved] The inventions are, Tepaka
Problem specific to the sound
It was made to pay attention and to solve this,
It is an object of the present invention to provide an engine valve timing control device capable of suppressing occurrence of a tapping sound due to thrust fluctuation while shortening the entire length of a cylinder head provided with a camshaft moving means.

[0006] One embodiment of the invention is to a Tepakamu the cam above mentioned cam shaft moving means side becomes large,
When the camshaft is moved against the thrust force by the double-acting hydraulic cylinder, the hydraulic chamber on the head side of this double-acting hydraulic cylinder is sealed to generate high oil pressure easily without oil leakage. It is an object of the present invention to provide a valve timing control device for an engine that can perform the following .

[0007]

An engine according to the present invention .
A valve timing control device of an engine includes a camshaft having a cam tapered in an axial direction, and a camshaft moving means for moving the camshaft in an axial direction to vary a valve lift amount. A timing control device, wherein the camshaft moving means is formed integrally with a cylinder member constituting a double-acting hydraulic cylinder, a piston member inserted into the cylinder member and reciprocating in a camshaft direction, and a piston member. is, while allowing the rotation of the cam shaft, and a thrust control member to be engaged with the cam shaft end so as to restrict the movement of the thrust direction of the mosquito <br/> arm shaft, the hydraulic pressure of the cylinder member The thrust regulating member is disposed in the room, and the cylinder member forms a bearing portion at the end of the camshaft .

In one embodiment of the present invention, the cam is a tapered cam having a large diameter on the cam shaft moving means side and a small diameter on the side opposite to the cam shaft moving means .

[0009]

Effects of the Invention According to the inventions, as well as providing the thrust control member described above to the hydraulic chamber of the cylinder member constituting a double-acting hydraulic cylinder, forming the bearing portion of the camshaft end portion in the cylinder member Therefore, the relief amount corresponding to the stroke for moving the camshaft may be a total of two places, that is, the distance between the cam and the rod cover of the double-acting hydraulic cylinder and the distance at which the piston member moves backward in the forward movement. Can be shortened.

When the above-mentioned thrust restricting member is disposed outside the hydraulic chamber of the cylinder member, the relief amount corresponding to the stroke for moving the cam shaft is set between the cam and the journal provided on the cylinder head. And the rod cover of the hydraulic cylinder require a total of three distances in which the piston member moves backward during forward movement. However, the above configuration of the present invention makes it possible to shorten the overall length of the cylinder head as described above. it can. Moreover, the thrust restricting member, which is formed integrally with the piston member and permits rotation of the camshaft , is locked to the end of the camshaft to restrict the movement of the camshaft in the thrust direction. Since it is arranged inside, there is an effect that generation of a tapping sound due to thrust fluctuation can be suppressed by a damping effect in oil.

[0011] According to one embodiment of the present invention, in the cam of the above mentioned cam shaft moving means side large diameter, since the anti-cam-axis moving means side is set to Tepakamu whose diameter, by the above-mentioned double-acting hydraulic cylinders When the camshaft is moved against the thrust force, it is necessary to generate a high hydraulic pressure against the thrust force in the head-side hydraulic chamber of the double-acting hydraulic cylinder. At this time, the bearing at the end of the camshaft in the cylinder member is formed on the rod cover of the rod-side hydraulic chamber, so that the above-mentioned head-side hydraulic chamber can have a sealed structure. There is an effect that a high oil pressure can be easily generated without leakage. Therefore, there is an effect that the camshaft can be moved against the thrust force without oil leakage .

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below in detail with reference to the drawings. The drawing shows a valve timing control device of an engine having a DOHC structure having two intake valves and two exhaust valves. In FIG. 1, the valve timing control device of the engine includes a camshaft 1 and one end of the camshaft 1 (FIG. And a cam pulley 2 interlocked with a crank pulley via a timing belt to change the relative rotation phase between the camshaft 1 and the cam pulley 2 to change the valve timing. The camshaft 1 is provided with tapered cams 3 and 3 integrally therewith, and the camshaft 1 is double-acting as a camshaft moving means for axially moving the camshaft 1 at the other end (right end in FIG. 1). A mold hydraulic cylinder 4 is provided to vary the valve lift amount.

The above-mentioned tapered cam 3 has a base circle portion 3B and a lift portion 3L as shown in FIG. 2, and its cam profile has a valve lift amount by moving the cam shaft 1 in the axial direction as shown in FIG. The diameter of the camshaft 1 is tapered, and the diameter of the cam pulley 2 is small and the diameter of the double-acting hydraulic cylinder 4 is large.

The configuration of the above-described cam pulley 2 is as follows. That is, the above-mentioned cam pulley 2 is formed in a bowl shape in cross section as shown in FIG. 1, and a positive displacement hydraulic pump for driving the above-mentioned double-acting hydraulic cylinder 4 with its discharge oil pressure is provided in an internal space 5 of this cam pulley 2. For example, a gear pump 6 is provided.

The gear pump 6 has an inner cover 7, an outer cover 8, an outer rotor 9, and an inner rotor 10, and includes a plurality of set bolts 11 (in FIG.
The outer cover 8 and the inner cover 7 are attached to the cylinder head cover 12 using only one set bolt 11).
And the cylinder head 13.

The inner rotor 10 which forms a part of the rotating member of the gear pump 6 has a bolt 1 as a fastening member.
4, is integrally fixed to the above-described cam pulley 2, rotates in synchronization with the cam pulley 2, and has a helical spline hole 15 in the inner rotor 10.

On the other hand, a helical spline shaft 16 meshing with the helical spline hole 15 is integrally formed at one end of the camshaft 1.
Accordingly, a helical spline mechanism that varies the relative rotational phase between the camshaft 1 and the cam pulley 2 by moving the camshaft 1 in the axial direction is configured.

A meshing space in which the helical spline hole 15 and the helical spline shaft 16 mesh with each other,
The clearance 1 is provided between the pump chamber 17 of the gear pump 6 and the pump chamber 17.
The gears 8 are communicated with each other through the helical spline 8 so that the rattle (hitting sound) caused by the backlash of the helical spline is damped in the oil filling the space.

Further, the suction side of the gear pump 6 is communicated with an oil gallery 19 in the cylinder head 13. On the other hand, in this embodiment, the gear pump 6 is dedicated to a valve timing control device, so-called VVT. Set to 15kgf / cm2 and
It is formed separately from the existing engine oil pump with a discharge pressure of about 4 kgf / cm2.

Further, the gear pump 6 sets the number of teeth and the phase so that the discharge pressure is maximized when the tapered cams 3, 3 lift the intake / exhaust valve (not shown) to the maximum. The thrust fluctuation urged to the camshaft 1 via the gear 3 and the pulsation of the discharge hydraulic pressure of the gear pump 6 are matched. In the drawing, reference numeral 20 denotes a seal member between the outer cover 8 and the inner rotor 10, and reference numeral 21 denotes a seal member between the inner cover 7 and the camshaft 1.

The double-acting hydraulic cylinder 4 for moving the camshaft 1 in the axial direction is constructed as follows. That is, a cylinder member 25 is formed by the three members of the cylinder tube 22, the rod cover 23, and the head cover 24. A piston member 26 that reciprocates in the cam axis direction is inserted into the cylinder member 25, and the above-described cylinder member 25 is formed. The inside is a hydraulic chamber 27 on the rod side and a hydraulic chamber 28 on the head side.
And divided into

As shown in FIG. 3, a seal member 29 is fitted around the piston member 26, and a thrust member for regulating the movement of the camshaft 1 in the thrust direction is provided on the rod side of the piston member 26. The regulating member 30 is formed integrally.

The thrust restricting member 30 has a U-shaped groove 31 for rotatably locking the other end of the camshaft 1. On the other hand, a small-diameter portion 1a and a flange-shaped large-diameter portion 1b are integrally formed on the other end side of the camshaft 1, and the small-diameter portion 1a is rotatably disposed in the U-shaped groove 31. The large-diameter portion 1b is rotatably disposed in a space between the thrust regulating member 30 and the piston member 26.

A key groove 32 having a predetermined length is formed in the piston member 26, and a key 33 provided integrally with the cylinder tube 22 is inserted into the key groove 32 so that the piston member 26 We are trying to prevent rotation.

In addition, the above-described thrust restricting member 30 is disposed inside the hydraulic chamber 27 on the rod side of the above-mentioned cylinder member 25, so that the hitting sound due to the fluctuation of the thrust force is reduced.
And the camshaft 1 is attached to the rod cover 23 of the cylinder member 25.
Is formed to rotatably support the end of the journal portion. The rod cover 23 and the head cover 24 are provided with hydraulic ports 35 and 36 for supplying and discharging hydraulic oil to and from the hydraulic chambers 27 and 28, respectively.

FIG. 4 shows a hydraulic circuit of the valve timing control device. The discharge line 37 of the gear pump 6 is connected to a P port P of a directional control valve 38 of a two-position, four-port type using a spring offset pilot system. T of control valve 38
A duty solenoid valve 4 is connected to a drain line 40 between the port T and an oil pan 39 of the engine as a tank.
1, the speed control and the position control of the piston member 26 are performed by setting the drain amount by the duty solenoid valve 41.

[0026] with connecting hydraulic ports 36 of double-acting hydraulic cylinder 4 via the pilot check valve 42 to the A port A of the direction system valve 38 described above, the B port B another pilot check valve 43 When the directional control valve 38 is switched to the left position in FIG. 4 when the hydraulic port 35 of the double-acting hydraulic cylinder 4 is connected via the, the piston member 26 is moved forward (leftward) and switched to the right position. The piston member 26 is configured to move backward (to the right).
Here, the above-mentioned one pilot check valve 42 is a pilot-operated check valve that releases its check function by the hydraulic pressure of the line 45, that is, the line pressure.

The illustrated embodiment is constructed as described above, and its operation will be described below. The rotation of the crankshaft of the engine is transmitted to the cam pulley 2 via the crank pulley and the timing belt, and the helical spline shaft 16 of the camshaft 1 passes through the helical spline hole 15 of the inner rotor 10 fixed integrally with the cam pulley 2.
, The camshaft 1 and the tapered cams 3, 3 rotate, and at the same time, the gear pump 6 is driven.

When changing the valve timing and the valve lift, the directional control valve 38 in the hydraulic circuit of FIG.
Is switched to the left position as shown in FIG.
Is supplied to the hydraulic chamber 28 on the head side of the cylinder member 25 through the discharge line 37, the P port P, the A port A, the line 45, the pilot check valve 42, and the hydraulic port 36. On the drawing of 26,
Movement to the left (forward movement) causes the camshaft 1 to move in the axial direction, and the helical spline mechanism changes the relative rotational phase between the camshaft 1 and the cam pulley 2 to change the valve timing and the taper cam. By the movement in the axial direction of 3, 3, the valve lift is changed in the large lift direction.

Conversely, when the directional control valve 38 is switched to the right position, the discharge hydraulic pressure from the gear pump 6 is changed to the discharge line 37, the P port P, the B port B, the line 44, the pilot check valve 43, and the hydraulic port 35. The camshaft 1 is supplied to the hydraulic chamber 27 on the rod side of the cylinder member 25 via the shaft member 25, so that the rightward movement (backward movement) of the piston member 26 in the drawing moves the camshaft 1 in the axial direction, and the helical spline mechanism As a result, the relative rotational phase between the camshaft 1 and the cam pulley 2 changes, and the valve timing changes, and the valve lift is changed in the small lift direction by the axial movement of the tapered cams 3.

By the way, the above-mentioned thrust restricting member 30 is disposed in the hydraulic chamber 27 of the cylinder member 25 constituting the double-acting hydraulic cylinder 4 and the cylinder member 25 is used to carry a bearing (journal) at the other end of the camshaft. (See section 34)
Is formed, the relief amount corresponding to the stroke for moving the camshaft is a total of two distances between the cam 3 and the rod cover 23 of the double-acting hydraulic cylinder 4 and the distance that the piston member 26 moves in the forward movement. And the overall length of the cylinder head 13 can be reduced.

When the above-described thrust restricting member is disposed outside the hydraulic chamber of the cylinder member, the relief amount corresponding to the stroke for moving the cam shaft is set between the cam and the journal provided on the cylinder head. And the rod cover of the hydraulic cylinder require a total of three distances in which the piston member moves backward during forward movement. However, the above configuration of this embodiment reduces the overall length of the cylinder head 13 as described above. be able to.

In addition, a thrust restricting member formed integrally with the piston member 26 to permit rotation of the camshaft 1 and to be locked to the other end of the camshaft to restrict the movement of the camshaft 1 in the thrust direction. Since 30 is disposed inside the hydraulic chamber 27 of the cylinder member 25, there is an effect that occurrence of a tapping sound due to thrust fluctuation can be suppressed by a damping effect in oil.

In the tapered cam 13, the hydraulic cylinder 4 serving as the camshaft moving means has a large diameter, and the tapered cam has a small diameter on the side opposite to the camshaft moving means. When moving the camshaft 1 against the pressure, it is necessary to generate a high oil pressure against the thrust force in the hydraulic chamber 28 on the head side of the double-acting hydraulic cylinder 4. At this time, since the journal portion 34 at the other end of the camshaft of the cylinder member 25 is formed on the rod cover 23 of the rod-side hydraulic chamber 27, the above-described head-side hydraulic chamber 28 can be sealed. Thus, there is an effect that a high hydraulic pressure can be easily generated in a state where there is no oil leakage in the hydraulic chamber 28 on the head side.
Therefore, there is an effect that the camshaft 1 can be moved against the thrust force without oil leakage.

Further, since the hydraulic chamber 27 is formed at least on the taper cam 3 side of the piston member 26, the taper cam 3 has a large diameter on the piston member 26 side and a small diameter on the opposite piston member side.
The direction in which the thrust force of the camshaft 1 is generated coincides with the direction of movement of the piston member 26 when the hydraulic pressure is supplied to the hydraulic chamber 27 on the cam side.

Therefore, when the piston member 26 is moved in the same direction as the thrust force generating direction, it is only necessary to supply a low-pressure oil pressure to the hydraulic chamber 27 on the cam side. The rod cover 23 of the above-described hydraulic cylinder 4 can be improved.
Can be used as the journal portion 34 of the camshaft 1.

In addition, when the tapered cam 3 lifts the intake / exhaust valve to the maximum, the positive displacement hydraulic pump (see gear pump 6)
Is set so that the discharge pressure becomes maximum, and the thrust fluctuation urged to the camshaft 1 via the tapered cam 3 and the pulsation of the discharge hydraulic pressure of the positive displacement hydraulic pump (see the gear pump 6) are illustrated. 5 can be matched.

As a result, for example, hunting caused by thrust fluctuation with respect to the taper cam stop position at the time of controlling the movement position of the taper cam 3 in the camshaft direction can be canceled by the discharge hydraulic pulsation, thereby improving controllability. There is an effect that can be.

FIG. 6 shows a reference example of a valve timing control device for an engine. In this reference example, a single-acting hydraulic cylinder 50, a so-called ram type cylinder, is used as a camshaft moving means. The single-acting hydraulic cylinder 50 has a cylinder member 53 having an inlet port 51 formed at a lower portion and an outlet port 52 also serving as an air vent at an upper portion.
A piston member 54 inserted into the cylinder member 53 so as to be able to reciprocate in the axial direction of the camshaft 1, a seal member 55 fitted on the outer peripheral portion of the piston member 54,
A thrust regulating member 57 integrally attached to the above-described piston member 54 via a piston rod 56 and a hydraulic chamber 71 formed on a side supporting thrust force are provided.

The aforementioned thrust regulating member 57 is a U-shaped groove 5 for rotatably supporting the small diameter portion 1a at the other end of the camshaft 1.
The small-diameter portion 1a described above is rotatably disposed in the U-shaped groove 58, and the large-diameter portion 1b at the other end of the camshaft 1 is provided.
Are rotatably disposed in the space 59 of the thrust regulating member 57.

[0040] In addition, in this reference example cylinder head 13
And a journal portion 60 on the other end side of the camshaft 1 is integrally formed, and a return spring 61 having a spring force in the same direction as the thrust force is stretched between the journal portion 60 and the above-described piston member 54. . The configuration of the cam pulley 2 side in FIG. 6 because it is identical to the previous embodiment, the same parts as the previous figures are denoted by the same reference numerals, and the detailed description thereof will be omitted.

FIG. 7 shows a hydraulic circuit of the valve timing control device shown in FIG. 6, in which a main flow line 62 is connected to the discharge side of the gear pump 6, and a fixed throttle 6 is connected to the main flow line 62.
3 (so-called orifice) and a check valve 64 are interposed. The tip of the main flow line 62 is connected to the inlet port 51 below the hydraulic cylinder 50.

A relief line 66 branched from the main flow line 62 at a branch point 65 is provided, and a two-position, two-port type first duty solenoid valve 67 is interposed in the relief line 66.

On the other hand, a drain line 68 is provided between the outlet port 52 above the hydraulic cylinder 50 and the oil pan 39 as a tank.
A fixed throttle 69 (so-called orifice) and a 2-position 2-port type second duty solenoid valve 70 are provided at 8.

The duty solenoid valves 67 and 70 have solenoids SOL1 and SOL2, respectively, and the first duty solenoid valve 67 has a solenoid S
When the OL1 is not energized (OFF), it is switched to the left position to relieve the hydraulic pressure, and the second duty solenoid valve 70 is switched to the right position when the solenoid SOL2 is energized (ON) to reduce the hydraulic pressure. It is configured to drain. The hydraulic circuit shown in FIG. 7 is configured to drive the piston member 54 in the axial direction based on the difference between the amount of hydraulic oil flowing into the hydraulic chamber 71 and the amount of hydraulic oil flowing out of the hydraulic chamber 71. The hydraulic pressure in the hydraulic chamber 71 and the spring force of the return spring 61 are set to be balanced under the condition of 50%.

The operation of the valve timing control device configured as described above will be described below with reference to time charts shown in FIGS. When moving the axial moving elements such as the camshaft 1, the tapered cam 3, the piston rod 56, the piston member 54, etc. to the high lift side shown by the arrow a in FIG. When the solenoid valve 67 is turned ON, the relief amount from the relief line 66 is set to zero, and the axial moving element moves in the direction of arrow a.

Next, the duty ratio of the second duty solenoid valve 70 is controlled from the time point t2 when the above-mentioned axial element reaches the target value shown in FIG. 8, and the amount of drain from the drain line 68 is controlled.

Next, at time t3, when the two duty solenoid valves 67 and 70 are turned off, the axial movement element is controlled to the target value. The air mixed in the oil in the hydraulic chamber 71 is bleed from the outlet port 52, so that it is possible to prevent a decrease in hydraulic rigidity due to air mixing.

Contrary to the above, when moving the axial moving elements such as the camshaft 1, the tapered cam 3, the piston rod 56, the piston member 54, etc. to the low lift side shown by the arrow b in FIG.
When the second duty solenoid valve 70 is turned on in response to the movement command signal at time t4 in FIG. 9, the amount of drain from the drain line 68 is set to the full amount, and the axial moving element moves in the direction of arrow b.

Next, at time t5 near the time when the above-mentioned axial movement element reaches the target value shown in FIG. 9, the duty ratio of the second duty solenoid valve 70 is controlled to control the amount of drain from the drain line 68 and the first duty. The duty solenoid valve 67 is turned on. Next, at time t6, when the two duty solenoid valves 67 and 70 are turned off, the axial driving element is controlled to the target value.

As described above, only the duty ratio control of the two duty solenoid valves 67 and 70 allows the
Since the control positions 3, 56 and 54 can be controlled with respect to the target value, the control response can be improved as compared with a hydraulic configuration in which a directional control valve is provided in the mainstream line 62. There is.

In the correspondence between the configuration of the present invention and the above-described embodiment, the cam of the present invention corresponds to the tapered cam 3 of the embodiment, and similarly, the cam shaft corresponds to the camshaft 1 and the camshaft. The moving unit corresponds to the hydraulic cylinder 4, the bearing unit corresponds to the journal unit 34, and the positive displacement hydraulic pump corresponds to the gear pump 6, but the present invention is limited only to the configuration of the above embodiment. Not something.

For example, the positive displacement hydraulic pump may be another constant displacement positive displacement hydraulic pump such as a vane pump or a rotary piston pump, instead of the gear pump 6 described above.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an engine valve timing control device according to the present invention.

FIG. 2 is a sectional view taken along line DD in FIG.

FIG. 3 is a perspective view of a piston member.

FIG. 4 is a hydraulic circuit diagram of the valve timing control device.

FIG. 5 is a characteristic diagram showing a state of coincidence between cam thrust force fluctuation and hydraulic pulsation.

FIG. 6: Reference of engine valve timing control device
Sectional drawing which shows a figure.

FIG. 7 is a hydraulic circuit diagram of the valve timing control device shown in FIG.

FIG. 8 is a time chart showing movement control to a high lift side.

FIG. 9 is a time chart showing movement control to the low lift side.

FIG. 10 is a sectional view showing a conventional engine valve timing control device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Cam shaft 3 ... Taper cam 4 ... Hydraulic cylinder 6 ... Gear pump (positive displacement hydraulic pump) 25 ... Cylinder member 26 ... Piston member 27,28 ... Hydraulic chamber 30 ... Thrust regulating member 34 ... Journal part

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akira Asai 3-1, Shinchi, Fuchu-cho, Aki-gun, Hiroshima Mazda Co., Ltd. (56) References JP-A-55-96310 (JP, A) -20164 (JP, Y1) (58) Field surveyed (Int. Cl. ⁷ , DB name) F01L 13/00 301

Claims (2)

(57) [Claims] An engine valve timing control comprising: a camshaft having a cam tapered in an axial direction; and camshaft moving means for moving the camshaft in the axial direction to vary a valve lift. An apparatus, wherein the camshaft moving means is integrally formed with a cylinder member forming a double-acting hydraulic cylinder, a piston member inserted into the cylinder member and reciprocating in the camshaft direction, Allow camshaft rotation
A thrust restricting member that is locked to an end of the camshaft to restrict the movement of the camshaft in the thrust direction. The thrust restricting member is disposed in a hydraulic chamber of the cylinder member. A valve timing control device for an engine, wherein a cylinder member forms a bearing at the end of the camshaft. 2. The valve timing control device for an engine according to claim 1, wherein said cam is a tapered cam having a large diameter on the camshaft moving means side and a small diameter on the side opposite to the camshaft moving means .