JP2738745B2 - Valve timing control device for DOHC engine - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve timing control device for an engine, and more particularly, to a DOHC engine having an intake camshaft and an exhaust camshaft, in which both intake timing and exhaust timing change. The present invention relates to an improvement in an arrangement position of a timing control mechanism in a case where the timing is controlled.

[Conventional technology]

Conventionally, as a valve timing control device of a DOHC engine, for example, there is one having the following structure. One end of the intake camshaft and one end of the exhaust camshaft are simultaneously driven by a crankshaft via one transmission member, and one end of the intake camshaft is provided with an opening / closing timing of an intake valve at a high speed at a low speed. In some cases, an intake timing control mechanism that makes the timing earlier is mounted, and at one end of the exhaust cam shaft, an exhaust timing control mechanism that makes the opening / closing timing of the exhaust valve slower at a low speed than at a high speed.

[Problems to be solved by the invention]

However, due to the structure of the conventional valve timing control device, it is necessary to dispose each of the intake and exhaust timing control mechanisms on the same side of the intake camshaft and the exhaust camshaft and on the side where the transmission member is provided. There is. Therefore, the timing control mechanism having a relatively large arrangement space and a large weight is biased in one direction of the cam shaft. As a result, in this conventional apparatus, there is room for improvement in the balance between the arrangement space and the weight.

Further, since the intake and exhaust timing control mechanisms are separately provided on the intake and exhaust camshafts, respectively, it is necessary to provide a hydraulic control device comprising a control valve and a solenoid on each camshaft. Are required, and the cost increases accordingly, and two arrangement positions are required.

In addition, if the timing control mechanism is provided, the rotating mass of the camshaft increases accordingly, so that when the camshaft rotates while opening and closing the valve, the fluctuation of the tension applied to the transmission member that drives the camshaft, for example, the timing belt, is large. Become. In particular, when a timing control mechanism is provided for each camshaft and the belts are driven simultaneously by one belt, the above fluctuations become even larger,
There is a problem that the durability of the belt is reduced.

The present invention has been made in view of the above conventional problems,
It is an object of the present invention to provide a valve timing control device for a DOHC engine having a good balance in weight and arrangement space. Further, the invention of the first aspect requires only one hydraulic control device and one arrangement position. Another object of the present invention is to provide a valve timing control device which is good in cost and arrangement space, and can improve the durability of the transmission member.

[Means for solving the problem]

Accordingly, a first aspect of the present invention is a valve timing control device for a DOHC engine including an intake camshaft and an exhaust camshaft, wherein one end of one of the camshafts is driven by a crankshaft and the other camshaft is driven by the one camshaft. A first timing control mechanism for changing the opening / closing timing between a low speed and a high speed is provided at one end of the one cam shaft, and the other end of the one cam shaft drives the other end of the other cam shaft. At the other end of one camshaft, a second timing control mechanism for changing the opening / closing timing of the other camshaft between low speed and high speed is provided, and the one camshaft is supplied with hydraulic oil to both timing control mechanisms. A hydraulic passage to be provided is formed, and a hydraulic control device for opening and closing the passage is provided at an end of the one camshaft.

In a second aspect of the present invention based on the first aspect, one camshaft is driven by a crankshaft via a first transmission member, and the other camshaft is driven by the one camshaft via a second transmission member. And the second valve timing control mechanism is mounted on the other end of the other camshaft.

Here, the low speed and the high speed in the present invention mean the low and high engine rotation speeds, respectively. The first and second
The transmission member includes a transmission belt, a chain, and a gear.

The invention of the present application includes both a case where the intake camshaft is driven by the crankshaft and a case where the exhaust camshaft is driven by the crankshaft. When one end of the intake camshaft is driven by the crankshaft, the intake timing control mechanism is provided at one end of the intake camshaft, and the exhaust timing control mechanism is provided at the other end of the intake camshaft or the other end of the exhaust camshaft. . When one end of the exhaust camshaft is driven by the crankshaft, the exhaust timing control mechanism is provided at one end of the exhaust camshaft, and the intake timing control mechanism is provided at the other end of the exhaust camshaft or the other end of the intake camshaft. Become.

[Action]

In the present invention, one end of one of the intake and exhaust camshafts is driven by the crankshaft, and the other end of the one camshaft is driven by the other end of the other camshaft. The first timing control mechanism can be provided at one end of the one camshaft, and the second timing control mechanism can be provided at the other end of one of the camshafts. It can be arranged separately at both ends in the direction, and as a result, a good balance in weight and arrangement space is achieved.

Further, in the first aspect of the invention, the first and second timing control mechanisms are provided at one end and the other end of one camshaft, and are formed in the one camshaft so as to communicate with both timing control mechanisms. Since the hydraulic passage is configured to be opened and closed by the hydraulic control device, only one hydraulic control device is required.

According to the second aspect of the present invention, since the two timing control mechanisms are provided separately for one camshaft and the other camshaft interlocked via the second transmission member, the two timing control mechanisms are installed. As a result, the load fluctuation generated in the transmission member is distributed and added to the first and second transmission members, and the durability of the first transmission member is improved.

〔Example〕

 Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

FIGS. 1 to 8 show an embodiment according to the first aspect of the present invention.
FIG. 2 is a diagram for explaining a valve timing control device of a DOHC engine.

In the figure, reference numeral 1 denotes a V-type six-cylinder engine to which the present invention is applied. In the engine 1, an oil pan 3 is mounted on a lower surface of a cylinder body 2 in which six cylinders are formed at a predetermined bank angle. , A pair of cylinder heads on the top
The cylinder heads 4, 4 are fixed by head bolts, and the upper surfaces of the cylinder heads 4, 4 are covered with head covers 5, 5.

An intake port 4a to which an intake manifold is connected is formed inside the bank of each cylinder head 4, and an exhaust port 4b to which an exhaust manifold is connected is formed outside. An intake camshaft 6 is provided inside the bank and an exhaust camshaft 7 is provided outside the bank in parallel and rotatably on the mating surface of each cylinder head 4 with each head cover 5.

An intake timing control mechanism 8 is mounted on one end 6a of each intake camshaft 6. The intake timing control mechanism 8 includes an inner shaft 11 fixed to one end 6 a of the intake camshaft 6, and an intake pulley 12 mounted outside the shaft 11.
And a slide piston 13 inserted between the pulley 12 and the inner shaft 11. A drive belt 1 as a first transmission member is provided between the intake pulley 12 of each of the intake camshafts 6, 6 and the drive pulley 25a of the crankshaft 25.
7 are wound. The first transmission member may be a chain or a gear, and 26 is a tension pulley.

The inner shaft 11 has its connection hole 11a fitted to one end 6a of the intake camshaft 6 and a detent pin between the two.
14 is fixed to the intake cam shaft 6 by inserting a connecting bolt 15 into the one end 6a via a washer 15b. A hydraulic passage 15a is formed through the connecting bolt 15, and one end of the passage 15a communicates with a hydraulic passage 6c formed through the intake camshaft 6 over its entire length, and the other end of the inner shaft 11a. In the recess 11b. Reference numeral 6d denotes a hydraulic pressure introduction passage, which communicates with a lubrication hydraulic pump provided in the engine 1 through a hydraulic passage formed in the cylinder head 4, though not shown.

The slide piston 13 is a main piston 13a and a sub piston.
13b is connected with a bolt 13e, and is press-contacted by an urging spring. The urging spring 16 is urged outward by the urging spring 16 in the cam shaft direction. Helical splines 13c and 13d having opposite twisting directions are formed on the outer peripheral surface and the inner peripheral surface of the slide piston 13, and are formed on the inner peripheral surface of the intake pulley 12 and the outer peripheral surface of the inner shaft 11, respectively. It meshes with the helical splines 12b, 11c. Thus, the intake timing control mechanism 8 moves the slide piston 13 inward in the camshaft direction by hydraulic pressure to advance the opening / closing timing of the intake camshaft 6 with respect to the intake pulley 12 (FIG. 1). In the clockwise direction as viewed from the right side, it is relatively rotated by a predetermined phase angle (for example, 10 degrees).

An exhaust timing control mechanism 9 is mounted on the other end 6b of the intake camshaft 6. In this, a slide piston 13 is arranged on the outer periphery of the inner shaft 11, and a drive sprocket 19 is mounted on the outer periphery of the slide piston 13. The helical splines on the outer periphery and the inner periphery of the slide piston 13 are connected to the inner peripheral surface of the drive sprocket 11,
The helical spline on the outer peripheral surface of the inner shaft 11 is meshed, and basically the intake timing control mechanism 8
It is the same configuration as. However, the exhaust timing control mechanism 9 controls the drive sprocket 19 by moving the slide piston 13 inward in the cam shaft direction by hydraulic pressure.
At a predetermined phase angle (for example, 6 degrees) with respect to the intake camshaft 6.
However, the exhaust camshaft 7 is relatively rotated counterclockwise when viewed from the right side of FIG. 1, that is, in a direction in which the opening / closing timing of the exhaust camshaft 7 is delayed.

The cover 20 attached to the end of the driving sprocket 19
The control valve 21 which constitutes the hydraulic control device 30
A solenoid 22 for opening and closing the valve 21 is provided outside the valve 21. The control valve 21 is provided in a housing 23 having a hydraulic inlet 23a.
The plunger 24 having the hydraulic outlet 24a is inserted so as to be able to advance and retreat and urge in the retreating direction. The plunger 24 is closed when the plunger 24 is advanced, and opened when the plunger 24 is retracted. The solenoid 22 has a coil 22b disposed in a housing 22a, and an armature rod 22c inserted into the coil 22b. The hydraulic passage 6c is closed by moving the plunger 24 forward.

The driving sprocket 19 is connected to the exhaust sprocket 10 fixed to the other end of the exhaust cam shaft 7 by a driving chain 18. These sprockets 19,10, drive chain 18,
The control valve 21 is located in a chain chamber 4c formed at the other end of the cylinder head 4.

 Next, the operation and effect of this embodiment will be described.

In the present embodiment, the hydraulic oil from the hydraulic pump is introduced into the hydraulic passage 6c from the hydraulic introduction passage 6d of the intake camshaft 6. At this time, if the solenoid 22 is turned off, the plunger 24 of the control valve 21 is turned off. Retreats and the valve 21 is opened. For this reason, the hydraulic oil remains in the chain chamber 4c as it is.
Therefore, the hydraulic pressure does not act on either the intake timing control mechanism 8 or the exhaust timing control mechanism 9, and as a result, both the timing control mechanisms 8, 9 are turned off. On the other hand, when the solenoid 22 is turned on, the plunger 24 of the control valve 21 moves forward and the valve 21 is closed, and hydraulic pressure acts on the slide piston 13 of the timing control mechanisms 8 and 9.

Therefore, in the intake timing control mechanism 8, the advance of the slide piston 13 causes the intake camshaft 6 to rotate clockwise (in a direction to advance the opening / closing timing) relative to the intake pulley 12 by 10 degrees. In this embodiment, since the exhaust camshaft 7 is connected to the intake camshaft 6 by the chain 18, the advancement of the intake camshaft 6 is the same as that of the intake camshaft 6 as it is. However, as described above, the exhaust timing control mechanism 9 rotates the driving sprocket 19 counterclockwise relative to the intake camshaft 6 by the advance of the slide piston 13, and the advance angle of the intake camshaft 6 by that amount. The effect on the exhaust camshaft 7 is reduced.

The advance and retard angles of the intake camshaft 6 and the exhaust camshaft 7 will be described in more detail with reference to FIGS. Fifth
FIG. 5A shows the opening angles of the intake valve (IN) and the exhaust valve (EX) by crank angles. In the figure, the solid lines show the cases where each of the timing mechanisms is off, and the dashed line shows the cases where it is on. FIG. 5 (b) shows the intake camshaft (IN) and the exhaust camshaft (EX).
Is shown by a cam angle, and clockwise and counterclockwise arrows in the figure indicate advance and retard of opening and closing timing, respectively. FIG. 8 shows that each of the timing mechanisms 8, 9 is turned on,
It is a figure which shows an OFF condition, and the area | region divided by the engine rotation speed-load (inventive torque) characteristic curve and a thin line in a figure.
In A and B, both the timing mechanisms 8 and 9 are simultaneously turned on or off, respectively.

In the present embodiment, as described above, the intake timing control mechanism 8 and the exhaust timing control mechanism 9 are configured to be turned on or off at the same time, and when both mechanisms 8 and 9 are off (FIG. 8). In the area B), the intake valve is
At 0 degrees, the exhaust valves reach their maximum opening at 108 degrees before top dead center, respectively, and the lap angle with both valves open simultaneously is 4 degrees.

When both of the above mechanisms are on (region A in FIG. 8),
The opening / closing timing of the intake valve is advanced by 20 degrees (10 degrees at the camshaft angle) by the intake timing control mechanism 8. on the other hand,
Exhaust timing control mechanism is 12 degrees (cam shaft angle is 6 degrees)
Because of the delay, the opening and closing timing of the exhaust valve is the difference between the above 20 degrees and 12 degrees, that is, 8 degrees (the camshaft angle is 4 degrees).
Degrees) faster. Thereby, the valve wrap angle can be increased from 4 degrees to 16 degrees.

The opening and closing timings of the intake valve and the exhaust valve are determined by the intake timing control mechanism 8 and the exhaust timing control mechanism 9.
The desired timing can be realized by appropriately setting the advance and retard amounts of the.

For example, as shown in FIG. 6, if the amounts of advance and retard are the same (camshaft angle is 10 degrees), the opening and closing timing of the intake valve is advanced by 20 degrees at the crank angle while the exhaust valve is opened. The opening / closing timing can be kept unchanged. This can increase the wrap angle from 4 degrees to 24 degrees.

Further, as shown in FIG. 7, when the retard amount of the exhaust timing mechanism 9 is made larger than the advance amount of the intake timing mechanism 8, the opening timing of the exhaust valve is advanced by 10 degrees while the opening timing of the intake valve is advanced by 20 degrees. It can be delayed. Thereby, the wrap angle can be further increased from 4 degrees to 34 degrees.

As described above, in the present embodiment, the intake camshaft 6 is connected to the crankshaft.
The intake camshaft 6 drives the exhaust camshaft 6 at one end and an intake timing control mechanism 8 at one end of the intake camshaft 6 and an exhaust timing control mechanism 9 at the other end. Therefore, the opening and closing timing of the intake valve and the opening and closing timing of the exhaust valve can be arbitrarily set by setting the advance and retard amounts of the respective control mechanisms.

In this case, the intake and exhaust timing control mechanisms 8, 9
Are arranged separately at both ends of the camshaft, so that a relatively large weight and an arrangement space can be divided into both, so that the weight and the arrangement space can be well balanced.

Further, since the intake and exhaust timing control mechanisms 8 and 9 are provided at both ends of the intake camshaft 6, there is an advantage that only one set of the hydraulic control device 30 is required, and the cost and the arrangement location are only one.

9 to 11 are views for explaining one embodiment of the invention of the second aspect of the present application, and the same reference numerals as those in FIG. 1 denote the same or corresponding parts.

In this embodiment, an exhaust timing control mechanism 9 is provided at the other end 7b of the exhaust camshaft 7, and the driving sprocket 19 of the mechanism 9 and the intake sprocket 10 fixed to the other end of the intake camshaft 6 are different from each other. They are connected by a drive chain 18 as a second transmission member. The second transmission member includes a transmission belt,
It may be a gear.

In this embodiment, a hydraulic control device 30 is also provided on the other end 6b side of the intake camshaft 6. The control valve 21 of the device 30 is inserted and fixed to the other end 6b, and a solenoid 22 disposed outside the control valve 21 is fixed to the chain chamber 4c of the cylinder head 4.

Here, the intake and exhaust timing control mechanisms 8 and 9 of this embodiment are used.
Are configured to advance, for example, 20 degrees and 20 degrees in crank angle, respectively.

In this embodiment, the intake and exhaust timing control mechanisms 8 and 9 are mounted on one end and the other end of the intake and exhaust cam shafts 6 and 7, respectively.
Since the hydraulic control device 30 is provided at the other end of each of the camshafts 6 and 7, the respective timing control mechanisms 8 and 9 can be simultaneously turned on or off as in the first embodiment, and the respective timing control mechanisms 8 and 9 can be simultaneously turned on and off. , 9 can be turned on and off individually.
For example, as shown in FIG. 11 (a), both mechanisms are turned on or off in regions A and B, and the intake side is turned off and on in region C.
The exhaust side can be turned on. Alternatively, as shown in FIG. 2B, the area B is divided into D and E,
In the region D, the intake side is turned on and the exhaust side is turned off. In the region E, both can be turned off.

For example, when the intake side is turned off and the exhaust side is turned on (region C), the opening and closing timing of the intake valve remains unchanged when the intake side is turned off, and the exhaust valve is turned on when the exhaust side is turned on, as shown in FIG. Only the opening / closing timing can be delayed by 20 degrees in crank angle, and the lap angle is changed from 4 degrees when both are off to 24 degrees. In the figure, the solid line shows the state at the time of off, and the chain line shows the state at the time of on.

In this embodiment, the intake timing control mechanism 8 is connected to the intake camshaft 6 and the exhaust timing control mechanism 9 is connected to the exhaust camshaft 7.
Respectively, so that the relative rotation directions of the camshaft and the pulley when turned on are the same, and the amount of advance and retard is the same for both timing control mechanisms. 8, 9 can be shared. Furthermore, since each control mechanism is provided on a separate camshaft and connected by the transmission chain 18, fluctuations in tension caused by the installation of the timing control mechanisms 8, 9 are distributed to the drive belt 17 and the transmission chain 18. In particular, no excessive load fluctuation occurs in the drive belt 17, and the durability of the belt 17 can be greatly improved.

In the above embodiment, as shown in FIG. 8 (a), each timing control mechanism is turned on at the time of low-speed rotation, but may be turned on at the time of high-speed rotation. This is advantageous in that the generated hydraulic pressure is high during high-speed rotation. In this case, it is needless to say that the intake timing control mechanism must be configured to delay the on-time opening / closing timing, and the exhaust timing control mechanism must be configured to advance on-time.

Further, in the above embodiment, the advance amount and the retard amount were respectively constant, but by changing the structure of the timing control mechanism, the magnitude of the hydraulic pressure, etc., for example, the area A in FIG. The amount of retardation can be changed with C.

For example, in the area A, the retardation amount shown in FIG. 5A is used, and in the area C, the retardation amount shown in FIG.
The overlap amount (24 degrees) in the region C is larger than the overlap amount (16 degrees) in the region A, and the pulsation effect of the exhaust can be effectively used in a high rotation and high load region, and the performance is improved.

Further, in the area A, by adopting the retard amount shown in FIG. 7A, the overlap amount (34 degrees) in the area A becomes larger than the overlap amount in the area C, and the fuel efficiency is improved.

In the above embodiment, the case where the intake camshaft 6 is driven by the crankshaft 25 has been described. However, the present invention can of course be applied to the case where the exhaust camshaft is driven by the crankshaft. In the above embodiment, the V-type engine has been described. However, the present invention can of course be applied to other in-line engines.

〔The invention's effect〕

As described above, according to the valve timing control mechanism of the DOHC engine according to the present invention, since the intake and exhaust timing control mechanisms are arranged separately at both ends in the cam axis direction, the balance in terms of weight and arrangement space is improved. Has an effect,
According to the first aspect of the present invention, since the timing control mechanisms are provided at both ends of the same camshaft, only one set of hydraulic control devices is required, and thus only one location is required. In addition, there is an advantageous effect in terms of the number of locations.

[Brief description of the drawings]

1 to 8 are views for explaining a valve timing control device according to an embodiment of the invention of the first aspect. FIG. 1 is a partially sectional plan view with a head cover removed, and FIG. FIG. 3 is a sectional plan view of a timing control mechanism portion, FIG. 3 is a partial sectional plan view of a hydraulic control device portion, FIG. 4 is a side view of an engine employing the embodiment device, FIG. 6 (a) and 7 (a) show the opening / closing timing in terms of the crank angle, respectively. FIGS. 5 (b), 6 (b) and 7 (b) show the advance of the camshaft, respectively. , A diagram showing the amount of retardation,
8 (a) and 8 (b) are diagrams showing the on / off region of the timing control mechanism by an engine speed-load characteristic curve, respectively, and FIGS. Fig. 9 is a view for explaining the embodiment, Fig. 9 is a partial cross-sectional plan view with the head cover removed, Fig. 10 (a) is a diagram showing opening / closing timing by crank angle, and Fig. 10 (b) is FIGS. 11 (a) and 11 (b) show the amounts of advance and retard of the camshaft. FIGS.
It is a figure shown by a load characteristic curve. In the figure, 1 is a DOHC engine, 6 and 7 are intake and exhaust camshafts (one and the other camshafts), 6a and 6b are one end and the other end of the intake camshaft, 7b is the other end of the exhaust camshaft, and 8 is An intake timing control mechanism (first timing control mechanism), 9 is an exhaust timing control mechanism (second timing control mechanism), and 25 is a crankshaft.

Claims (3)

(57) [Claims] In a valve timing control device for a DOHC engine having an intake camshaft and an exhaust camshaft, one end of one of the camshafts is driven by a crankshaft, and one end of the one camshaft is A first timing control mechanism for changing the opening / closing timing of the one cam shaft between a low speed and a high speed is provided. The other cam shaft is driven by the other end of the one cam shaft, and the other cam shaft is driven by the other cam shaft. At the other end,
A second timing control mechanism for changing the opening / closing timing of the other camshaft between a low speed and a high speed is provided, and a hydraulic passage for supplying hydraulic oil to the two timing control mechanisms is formed in the one camshaft. A valve timing control device for a DOHC engine, wherein a hydraulic control device for opening and closing the hydraulic passage is provided at an end of the one camshaft. 2. A valve timing control device for a DOHC engine having an intake camshaft and an exhaust camshaft, wherein one end of one of the camshafts is driven by a crankshaft via a first transmission member. At one end of the camshaft, a first timing control mechanism for changing the opening / closing timing of the one camshaft between a low speed and a high speed is provided. A second timing control mechanism for driving the other end of the other camshaft and changing the opening / closing timing of the other camshaft between low speed and high speed is provided at the other end of the other camshaft. Characteristic valve timing control device for DOHC engine. 3. The camshaft according to claim 1, wherein the other camshaft is an intake camshaft.
An exhaust camshaft, wherein the first timing control mechanism is configured to make opening / closing timing by the intake camshaft faster at high speeds than at high speeds, and the second timing control mechanism is configured to reduce opening / closing timing by the exhaust camshafts at low speed. 3. The DO according to claim 1 or 2, wherein the time is set to be the same as or higher than the high speed.
Valve timing control device for HC engine.