JPH0666111A - Engine power transmission - Google Patents

Abstract

(57) [Summary] (Correction) [Purpose] When transmitting the power of the crankshaft to the exhaust side cam gear through the transmission gear in the engine in which the intake camshaft and the exhaust camshaft are linked by the cam gear, Suppresses noise caused by gear backlash. [Structure] Two friction gears 47, 48 are attached to both sides of the exhaust side cam gear 36 by being pressed against each other by a spring force of a disc spring 49, and the friction gears 47, 48 have one more tooth than the cam gear 36. Set the friction gear 47 near the camshaft shaft end to the exhaust side cam gear 36
A friction gear 48 closer to the center of the camshaft shaft that has one less tooth
Is engaged with the cam gear 34 of the intake side camshaft with which the exhaust side cam gear 36 is meshed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention provides a cylinder head with a camshaft for opening and closing an intake valve and a camshaft for opening and closing an exhaust valve, and both camshafts are interlocked by a cam gear. The present invention relates to a power transmission device for an engine, and more particularly to a device for transmitting power of a crankshaft to both camshafts.

[0002]

2. Description of the Related Art For example, in Japanese Patent Laid-Open No. 2-221616, in an engine of an automobile, a camshaft which controls opening and closing of an intake valve provided in a cylinder head is provided with a variable valve timing mechanism so that the operating state of the engine ( For example, a technique is disclosed in which the valve opening timing of the intake valve is appropriately adjusted according to the vehicle speed range). That is, the variable valve timing mechanism is formed between a housing integrally provided with a pulley that is interlocked with a crankshaft by a belt, and a camshaft that is projected into the housing, the housing and the camshaft. A hydraulic piston that meshes with each of the helical gears is interposed, and the hydraulic piston is moved in the axial direction of the camshaft by hydraulic pressure according to the operating state of the engine to change the phase between the pulley and the camshaft to absorb the suction. -It has a structure that adjusts the opening timing of the exhaust valve.

Further, in an automobile engine, a pair of cam shafts for intake and exhaust are provided in the cylinder head, and these cam shuts are interlocked by cam gears attached to the respective cam shafts, whereby the crankshaft Power is transmitted to one of the cam gears to rotate both cam shafts in synchronization with each other to control opening / closing of an intake valve and opening / closing of an exhaust valve.

By transmitting power by the cam gears in this manner, the interval between the cam shafts can be narrowed and the variable valve timing mechanism can be easily installed. That is, for example, when the camshafts are interlocked by, for example, a chain and a sprocket, in order to avoid interference between the sprockets, the diameter of these sprockets must be reduced, and thus it is necessary to apply a large tension to the chain. And a tensioning device must be placed between the camshafts. Therefore, the mounting space of the variable valve timing mechanism is compressed,
In addition, the space between the camshafts must be opened.

[0005]

By the way, in the valve operating mechanism for opening and closing the intake / exhaust valve by the camshaft which is interlocked with the cam gear as described above, the power of the crankshaft is transmitted to one of the camshafts. ,
It is necessary to attach a sprocket or pulley for chain or belt interlocking with the crankshaft to the camshaft, but a large diameter sprocket or pulley is necessary because it is necessary to decelerate and transmit the power of the crankshaft. Since it is attached, in the case of an engine in which the variable valve timing mechanism described above is provided at the shaft end of the other camshaft, it interferes with the mechanism, making it difficult to reduce the interval between the camshafts. .

As a method of avoiding this, it is conceivable to transmit the power of the crankshaft to another shaft and engage the transmission gear attached to the shaft with the cam gear of one camshaft to transmit the power.

However, according to this method, in addition to the engagement between the cam gears, the engagement between the cam gear and the transmission gear occurs, so that the number of gear backlash occurrence points increases. As a result, backlash occurs due to torque fluctuations of the camshaft due to changes in engine speed and opening / closing of intake / exhaust valves, and noise is generated.

Therefore, it is an object of the present invention to provide a power transmission device capable of preventing the occurrence of backlash in a gear meshing portion even when an engine is provided with a variable valve timing mechanism.

[0009]

[Means for Solving the Problems] That is, claim 1 of the present invention.
According to the invention described in (1st invention), a pair of cam shafts for opening and closing an intake valve and an exhaust valve of each cylinder are provided on a cylinder head, and both cam shafts are provided for the respective cam shafts. In an engine adapted to be interlocked with a cam gear attached to a shaft, a transmission gear rotated by the crankshaft is provided between both camshafts and the crankshaft,
The transmission gear is meshed with one of the cam gears, two friction gears are attached to the one cam gear, one friction gear is meshed with the other cam gear, and the other friction gear is It is characterized in that it is meshed with a transmission gear.

The invention according to claim 2 (hereinafter referred to as the second
(Referred to as an invention), a cylinder head is provided with a pair of cam shafts for opening and closing an intake valve and an exhaust valve of each cylinder, and both cam shafts are interlocked by cam gears attached to the respective cam shafts. In an engine in which any one of the camshafts is equipped with a variable valve timing mechanism for adjusting the valve opening timing, a transmission gear rotated by the crankshafts is provided between the camshafts and the crankshafts. , The transmission gear is meshed with a cam gear on the side of the camshaft which is not equipped with the variable valve timing mechanism, and two friction gears are attached to the cam gear. Mesh the friction gear with the transmission gear,
The other friction gear is meshed with a camshaft-side cam gear equipped with a variable valve timing mechanism.

[0011]

According to the first aspect of the invention, the camshaft for the intake valve and the camshaft for the exhaust valve are interlocked by the cam gear, and the cam gear of either camshaft is interlocked with the crankshaft. In the case of gears meshing with each other, two friction gears are provided on the cam gear meshing with the transmission gear, one friction gear meshes with the transmission gear, and the remaining friction gear meshes with the other cam gear. Therefore, backlash due to torque fluctuations between the transmission gear, the cam gear, and the cam gears is eliminated.

By the way, the variable valve timing mechanism described in the above publication is usually attached to the shaft end of the camshaft, and is provided with the above-mentioned housing, hydraulic piston, hydraulic control means, etc. The mechanism is relatively large, and it has a structure protruding from the engine. Therefore, if an attempt is made to add a mechanism for preventing backlash to an engine equipped with such a variable valve timing mechanism, the total length of the engine may be further increased, and it may be difficult to mount the engine on a vehicle.

On the other hand, according to the second aspect of the present invention, in any one of the above-mentioned two friction gears, the friction gear on the camshaft shaft end side is provided in which one of the camshafts is provided with the variable valve timing mechanism. Is engaged with the transmission gear, and the friction gear closer to the center of the shaft than the friction gear on the shaft end side is engaged with the cam gear of the camshaft equipped with the variable valve timing mechanism. The valve timing mechanism can be located closer to the center of the camshaft, and the protrusion of the variable valve timing mechanism can be suppressed, so that it is possible to suppress an increase in the total length of the engine.

[0014]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a front view of a V-type engine (for example, a V-type 6-cylinder engine) 1 having two banks A and B, and a crankshaft 1 of the engine E (see FIG. 2).
The belt 8 is wound around the crank pulley 2 attached to the, the pulley 3 attached to the oil pump, the pulley 5 attached to the supercharger 4, the auto tensioner 6, and the idler 7,
The power of the crankshaft 1 is transmitted to the supercharger 4, and these devices are driven. Further, the crank pulley 2, the pulley 10 attached to the cooler compressor 9, the pulley 12 attached to the water pump 11, the pulley 13 attached to the power steering pump, the pulley 15 attached to the alternator 14, and the idler 16 , 17, and a belt 18 is wound around the cooler compressor 9, the water pump 11, the power steering pump, and the alternator 14, and the power of the crankshaft 1 is transmitted to drive these devices. There is.

The cylinder head 19 of each of the banks A and B has a camshaft 2 for opening and closing an intake valve.
0 and a camshaft 21 for opening and closing the exhaust valve are respectively provided, and the above-mentioned supercharger 4 is arranged between the banks A and B.

In this case, in each of the banks A and B, the intake manifold 22 is provided on the supercharger 4 as shown in FIG. 1, and the cylinders provided on the cylinder blocks 23 of the banks A and B are also provided. Head 24
In FIG. 3, the intake valve 27 and the exhaust valve 28 that open and close the intake port 25 and the exhaust port 26 of each cylinder are arranged in a V shape with respect to the center line O of the cylinder bore, and the intake valve The structure is such that 27 is located inside the bank on the engine center side close to the supercharger 4 and the intake manifold 22, and the exhaust valve 28 is located outside the bank. The intake port 25 communicates with the combustion chamber 29 and is connected to the intake manifold 25. 22 is connected, and the exhaust port 26 is connected to an exhaust manifold (not shown).

Further, in the above cylinder head 24, the intake camshaft 20 described above is provided above the intake valve 27.
Is provided, and the exhaust camshaft 21 is provided above the exhaust valve 28.
And the tappets 30 and 31 of the intake valve 27 and the exhaust valve 28 are applied to the cams 20a and 21a formed on the camshafts 20 and 21 from below by the force of the spring members 32 and 32, respectively. 20, 2
With the rotation of 1, the intake valve 27 and the exhaust valve 28 are driven up and down by the cams 20a and 21a, and the intake port 25 and the exhaust port 26 are opened and closed.

As shown in FIGS. 2 to 4, a variable valve timing mechanism 33 is provided at the shaft end of the intake camshaft 20 among the camshafts 20 and 21. That is, the variable valve timing mechanism 33 is used in the cam gear 3
4 has a housing 35 fixed to the outer surface,
An end portion of the intake camshaft 20 is projected into the housing 35, a helical gear is formed on an inner peripheral surface of the housing 35 and an outer peripheral surface of the camshaft 20, and a hydraulic piston (not shown) meshing with both helical gears is formed. The engine E is provided between the housing 35 and the camshaft 20.
The hydraulic piston is driven in the axial direction of the camshaft by the hydraulic mechanism that operates according to the operating state of the vehicle (for example, the speed of the vehicle), and the housing 35, the cam gear 34, and the camshaft 20 are relatively rotated, and the intake air is thereby obtained. The valve opening timing of the valve 27 is adjusted.

A cam gear 36 meshed with a cam gear 34 on the intake camshaft 20 side is fixed to the shaft end of the other exhaust camshaft 21, whereby the intake camshaft 20 and the exhaust camshaft 21 are synchronized. It is designed to rotate in conjunction with each other.

On the other hand, in the cylinder head 24 described above, the intermediate shaft 37 shown in FIG.
The intermediate shaft 37 is fitted with a sleeve 39 having a transmission gear 38 fixed thereto, the gear 38 meshes with the cam gear 36 of the exhaust camshaft 21, and the sprocket 40 is fixed to the sleeve 39. The chain 42 is wound around the sprocket 40 and the sprocket 41 fixed to the crankshaft 1 so that the power of the crankshaft 1 is input to the transmission gear 38. Further, in this power transmission mechanism, a tension lever 45 that rotates about a fulcrum shaft 43 with respect to a chain 42 that connects the sprockets 40 and 41 and that is pressed against the chain 42 by an actuator 44 is provided. Four
A chain guide 46 is provided at the opposite position across the two.

In FIG. 1, the crankshaft power transmission to the bank A on the right side of the drawing and the crankshaft power transmission to the bank B on the left side of the drawing appear to be performed on the front surface of the engine E. This is a drawing consideration so that the power transmission mechanism to the banks A and B can be clearly understood. In practice, the power transmission to the right bank A is performed in front of the engine because of the weight balance of the engine E. In this case, power is transmitted to the left bank B on the engine back side. In that case, as is clear from the drawing, the structure of the power transmission mechanism to the right bank A (variable valve timing mechanism 35, cam gears 34, 36, transmission gear 3
8, sleeve 39, sprockets 40, 41, chain 4
2, tension lever 45, chain guide 46, etc.)
If it is rotated 180 degrees as it is, it can be used as it is as a power transmission mechanism of the left bank B.

In addition, two friction gears 47, 48 are applied to the cam gear 36 on the exhaust camshaft 21 side with the cam gear 36 sandwiched from both sides, and these friction gears 47, 48 are made into a disc spring 49. , 49
Then, the cam gear 36 is fitted until it hits the flange 50 formed on the camshaft 21, and the nut 52 is tightened to the screw portion 51 formed on the shaft end of the camshaft 21 to fix the cam gear 36. The friction gears 47 and 48 are elastically fastened to the cam gear 36 by disc springs 49 and 49 while being fixed. Then, the friction gear 47 located on the shaft end side of the cam shaft 21 is engaged with the transmission gear 38 across the cam gear 36, and the other friction gear 48 distant from the cam shaft shaft end is connected to the cam gear 34 (in the variable valve timing mechanism 33). In other words, it meshes with the cam gear 34) on the intake camshaft 20 side. In that case, the number of teeth of the friction gear 47 meshing with the transmission gear 38 is one more than the number of teeth of the cam gear 34.
On the contrary, the number of teeth of the friction gear 48 meshing with the gear 4 is reduced by one.

In such an engine E, the power of the crankshaft 1 associated with the starting of the engine E is transmitted through the sprockets 40, 41 and the chain 42 to the sleeve 39.
The transmission gear 38 is rotated, the exhaust side cam gear 26 is rotated, the exhaust camshaft 21 is rotated, and the intake side cam gear 34 and the camshaft 20 are interlocked and rotated. Therefore, the intake valve 27 and the exhaust valve 28 of each cylinder are opened and closed.

In this case, when the power is transmitted from the transmission gear 38 to the exhaust-side cam gear 36 and when the power is transmitted from the exhaust-side cam gear 36 to the intake-side cam gear 34, the engine speed changes and the camshafts 20 and 21 move. The gear backlash that occurs due to torque fluctuation is caused by the transmission gear 38 and the cam gear 36 side being meshed by the friction gear 47, and the cam gear 36 and the cam gear 34
Since the side and the side are meshed with each other by the friction gear 48, the generation thereof is prevented at each meshing portion, and the noise generation due to the backlash can be suppressed.

That is, at the meshing portion of the transmission gear 38 and the cam gear 36, the number of teeth of the friction gear 47 is one more than the number of teeth of the cam gear 36, so that the rotational force from the transmission gear 38 to the cam gear 36 is increased. When told
The rotation of the friction gear 47 is delayed by one tooth with respect to the rotation of the cam gear 36.
The front portion in the rotational direction of the teeth of the friction gear 47 comes into contact with the rear portion in the rotational direction of the teeth of the transmission gear 38 that is pressing, thereby preventing backlash. Further, since the number of teeth of the friction gear 48 is one less than the number of teeth of the cam gear 36 at the meshing portion between the cam gears 36 and 34, when the rotational force is transmitted from the cam gear 36 to the cam gear 34, Number of teeth per rotation of
As a result, the rotation of the friction gear 47 progresses, so that the front portion in the rotational direction of the teeth of the cam gear 34 pushed by the cam gear 34 comes into contact with the rear portion in the rotational direction of the teeth of the friction gear 48. , Backlash is prevented.

Further, since the friction gear 48 near the center of the shaft is meshed with the cam gear 34 with the cam gear 36 interposed therebetween, the variable valve timing mechanism 33 having the cam gear 34 is provided with a space L between the friction gears 47 and 48.
Therefore, the camshaft 20 can be positioned closer to the center of the axis, and thus the amount of projection of the variable valve timing mechanism 33 from the cylinder head 24 can be reduced, and the increase in the total length of the engine can be suppressed.

In addition, since the friction gear 47 on the camshaft shaft end side is meshed with the transmission gear 38, the camshaft 2 provided with the friction gears 47 and 48.
Similarly, the shaft end of No. 1 can be pulled toward the center of the shaft by the same distance as described above, and the position of the nut 52 for attaching the cam gear 36 and the friction gears 47 and 48 to the cam shaft 21 is also near the cylinder head 24. Therefore, the interference between the nut 52 and the sprocket 40 can be avoided.

Although the above embodiment has been described by taking the V-type engine as an example, it goes without saying that it can be applied to other engines.

[0030]

As is apparent from the above description, according to the present invention, a cam gear meshing with a transmission gear is provided with two friction gears, one friction gear is meshed with the transmission gear, and the other is Since the friction gear meshes with the other cam gear, backlash is eliminated due to torque fluctuation between the transmission gear, the cam gear, and between the cam gears, and noise generation can be eliminated.

Of the above two friction gears, the friction gear on the camshaft shaft end side is meshed with the transmission gear, and the friction gear closer to the shaft center than the shaft end side friction gear is a variable valve timing mechanism. Since it meshes with the cam gear of the provided camshaft, the variable valve timing mechanism can be positioned closer to the axial center of the camshaft by the distance between both friction gears, and the protrusion of the variable valve timing mechanism can be suppressed. Therefore, it is possible to suppress an increase in the total length of the engine.

[Brief description of drawings]

FIG. 1 is a front view of a V-type engine according to the present invention.

FIG. 2 is an enlarged view of a crankshaft power transmission mechanism portion of the engine.

FIG. 3 is a sectional view of a cylinder head portion of the engine.

FIG. 4 is a developed sectional view of a camshaft interlocking portion of the engine.

[Explanation of symbols]

 E engine 1 crankshaft 20,21 camshaft 24 cylinder head 27 intake valve 28 exhaust valve 33 variable valve timing mechanism 34,36 cam gear 38 transmission gear 40,41 sprocket 42 gear 47,48 friction gear

Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display area F16H 55/18

Claims (2)

[Claims] 1. A cylinder head is provided with a pair of cam shafts for respectively opening and closing an intake valve and an exhaust valve of each cylinder, and both cam shafts are interlocked by cam gears attached to the respective cam shafts. In such an engine, a transmission gear rotated by the crankshaft is provided between the camshafts and the crankshaft, and the transmission gear is meshed with one of the cam gears, and the cam gear of the one side is provided. A power transmission device for an engine, characterized in that two friction gears are additionally provided on one side, one friction gear is meshed with a cam gear on the other side, and the other friction gear is meshed with the transmission gear. 2. A cylinder head is provided with a pair of cam shafts for opening and closing an intake valve and an exhaust valve of each cylinder, respectively, and both cam shafts are interlocked by cam gears attached to the respective cam shafts. In an engine in which any one of the camshafts is equipped with a variable valve timing mechanism for adjusting the valve opening timing, a transmission gear rotated by the crankshafts is provided between the camshafts and the crankshafts. The transmission gear is meshed with a cam gear on the side of the camshaft which is not equipped with the variable valve timing mechanism, and two friction gears are attached to the cam gear. Of these friction gears, the friction near the camshaft shaft end is used. The gear meshes with the transmission gear and the other friction A power transmission device for an engine, wherein an engine gear is meshed with a camshaft-side cam gear equipped with a variable valve timing mechanism.