JPH07145713A - Valve timing controller for internal combustion engine - Google Patents

Abstract

PURPOSE:To remove a foreign material at a low cost and enhance reliability in a valve timing controller. CONSTITUTION:In a valve timing controller, a ring gear 26 is moved in the axial direction of a camshaft 2 by the energizing force of a fluid pressure from a pressurized fluid supply source so that the driving force of a pulley 5 is transmitted to the camshaft 2 by a helical gear, and rotating phases of the pulley 5 and the camshaft 2 are changed, thus adjusting an opening/closing timing of a valve. A shaft oil path 22 formed along the axial direction of the camshaft 2 is connected to a pressure chamber 29 facing to the helical gear. A hollow bolt 19 is screwed to the shaft oil path 22. The center hole 31 of the hollow bolt 19 is formed to have a small diameter with respect to the shaft oil path 22, thereby generating sedimentation in fluid. An annular recess 23 for catching a foreign material in the fluid is formed near the inlet of the center hole 31 of the hollow bolt 19 along the inner circumference of the shaft oil path 22.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an intake / exhaust valve opening / closing timing of an internal combustion engine, that is, a valve timing control, and more particularly to an internal combustion engine having a variable valve timing mechanism driven by hydraulic pressure. The present invention relates to a valve timing control device.

[0002]

2. Description of the Related Art Conventionally, a "valve timing control device for an internal combustion engine" disclosed in, for example, Japanese Patent Laid-Open No. 63-131808 is known as this type of technique.

In this valve timing control device, a cylindrical gear is interposed between the timing pulley and the cam shaft, and at least one of the teeth provided on the inner and outer circumferences of the cylindrical gear is formed as a helical tooth. Has been done. The rotation of the timing pulley is transmitted to the camshaft via this gear. Pressure chambers are formed in front of and behind the gear, and two hydraulic circuits for supplying hydraulic pressure to the pressure chambers are formed. When the hydraulic pressure is supplied to the pressure chambers by this hydraulic circuit, the cylindrical gear moves in the axial direction of the cam shaft due to the pressure balance between the pressure chambers. Therefore, the camshaft rotates relative to the timing pulley, and the opening / closing timing of the intake / exhaust valve is controlled.

As described above, in this device, hydraulic pressures are respectively supplied from the two hydraulic circuits to the pressure chambers in front of and behind the gear, and the gear moves. Therefore, this device has improved responsiveness as compared with a device in which one of the gears is biased by a spring, and valve timing control can be performed with high accuracy.

[0005]

However, in the above-mentioned prior art, the hydraulic circuit is configured to communicate with the engagement portion of the helical teeth via the two pressure chambers. Normally, it is difficult to completely remove foreign matter in the engine, and new foreign matter may be generated.The hydraulic circuit is directly connected to the main oil hole of the engine. Foreign matter in the engine lubrication system may flow in. Therefore, there is a possibility that foreign matter may reach the meshing portion of the helical teeth via the hydraulic circuit, and the gear may stick or lock, resulting in loss of timing control. Therefore, it is conceivable to provide a filter to remove the foreign matter, but in this case, there is a problem that the filter needs to be replaced, the work is extremely complicated, and the cost increases.

The present invention has been made in view of the above-mentioned circumstances, and an object thereof is to provide a highly reliable valve timing control device for an internal combustion engine which can remove foreign matter at low cost.

[0007]

In order to achieve the above object, according to the present invention, as shown in FIG. 1, a pulley provided on the outer periphery of a camshaft for driving a valve of an internal combustion engine, the camshaft and the pulley. A cylindrical ring gear that is interposed between and has teeth on the inner and outer peripheral surfaces, and at least one of which is a helical tooth, and a pressure chamber provided with fluid from a pressurized fluid supply source at both ends of the ring gear. Lead to
A pair of control passages for causing the fluid to act on both ends of the ring gear, and the ring gear is moved in the axial direction of the camshaft by the urging force of the fluid pressure from the pressurized fluid supply source to drive the pulley. In the variable valve timing control device configured to transmit the force to the camshaft by the teeth and change the rotational phase of the pulley and the camshaft to adjust the opening / closing timing of the valve, in the control passage,
The control passage leading to the pressure chamber facing the helical tooth includes a passage along the axial direction of the camshaft, and the passage is fluidized by reducing its diameter stepwise with respect to the pressurized fluid supply source side. A reduced diameter portion that causes stagnation is formed, and an annular shape that captures foreign matter in the fluid along the inner circumference of the passage along the camshaft in the vicinity of the inlet on the pressurized fluid supply side of the reduced diameter portion. The main point is that a recess is formed.

[0008]

According to the above construction, the ring gear is moved in the axial direction of the camshaft by the urging force of the fluid pressure from the pressurized fluid supply source. The driving force of the pulley is transmitted to the cam shaft by a helical tooth, and the rotational phase of the pulley and the cam shaft is changed to adjust the opening / closing timing of the valve.

At this time, the fluid from the pressurized fluid supply source is
A stagnation is caused by a diameter-reduced portion that is reduced in a step-like shape, passing through a passage along the axial center of the camshaft. Foreign matter in the fluid is trapped in an annular recess formed near the inlet of the reduced diameter portion and along the inner circumference of the passage along the camshaft.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the valve timing control device for an internal combustion engine according to the invention described above is embodied in a gasoline engine will be described in detail below with reference to FIGS.

FIG. 1 is a sectional view showing the structure of a mechanism for adjusting valve timing, that is, a VVT (variable valve timing) actuator or the like. The journal 2a of the camshaft 2 on the intake side is rotatably supported between the cylinder head 3 and the bearing cap 4 of the engine. A VVT actuator 1 is provided at the tip of the camshaft 2 integrally with the timing pulley 5. A head oil passage 6 is formed in the cylinder head 3 and the bearing cap 4 so as to extend therethrough.

A timing pulley housing 7 is provided at the tip of the camshaft 2. The timing pulley housing 7 is composed of a timing pulley 5 and a cover 8 assembled so as to cover one side surface of the timing pulley 5 and the tip end portion of the camshaft 2.
The timing pulley 5 has a substantially cylindrical shape, and is mounted so as to be rotatable relative to the cam shaft 2 by a boss 10 formed in the center thereof. A plurality of outer teeth 9 are formed on the outer circumference of the timing pulley 5, and a timing belt 11 is attached to the outer teeth 9. The timing pulley housing 7 is drivingly connected to a crankshaft (not shown) via the belt 11.

On the other hand, the cover 8 has a cylindrical shape with a bottom, and a flange 12 is formed on the outer periphery of the cover 8. The flange 12 is fixed to one side surface of the timing pulley 5 by a plurality of bolts 15 and pins 16. . A plurality of inner teeth 14 are formed on the inner periphery of the cover 8, and a communication hole 13 is formed at the center of the bottom. The communication hole 13 is sealed with a cap 13a. A space surrounded by the timing pulley 5 and the cover 8 is an accommodation space 17 inside the timing pulley housing 7.

In the housing space 17, a cylindrical inner cap 18 is fastened by a hollow bolt 19 to the tip of the camshaft 2 and is prevented from rotating by a pin 20. Peripheral wall 2 of the inner cap 18
4 is mounted so as to include the boss 10 of the timing pulley 5, and the both 3 and 10 are relatively rotatable. A plurality of outer teeth 25 are formed on the outer periphery of the peripheral wall 24 of the inner cap 18.

A ring gear 26 is interposed between the timing pulley housing 7 and the cam shaft 2, and the ring gear 26 connects the two 7, 2. That is,
The ring gear 26 has an annular shape and is housed in the housing space 17 of the timing pulley housing 7 so as to be capable of reciprocating along the axial direction of the camshaft 2. A flange 47 is formed on the outer circumference of the other end of the ring gear 26, and a seal ring 46 is fitted to the peripheral surface of the flange 47. Further, on the inner peripheral surface of the cover 8, the flange 47 is slidably in contact with the axial direction and the rotational direction via a seal ring 46.

The ring gear 26 has a plurality of teeth 27 and 28 provided on the inner and outer circumferences thereof, respectively.
The movement in the axial direction enables relative rotation with the camshaft 2. Then, the teeth 27 on the inner circumference of the ring gear 26
The outer teeth 25 of the inner cap 18 and the outer teeth 28 of the ring gear 26 mesh with the inner teeth 14 of the cover 8, respectively. Therefore, when the timing pulley housing 7 is rotationally driven, the timing pulley housing 7 and the inner cap 18 connected by the ring gear 26 are integrally rotated, and the camshaft 2 is also integrally rotated with the timing pulley housing 7. Driven.

In the accommodation space 17, the first hydraulic chamber 2 is provided between one axial end of the ring gear 26 and the bottom wall of the cover 8.
9 is formed. Similarly, in the accommodation space 17,
A second hydraulic chamber 30 is formed between the other end of the ring gear 26 in the axial direction and the timing pulley 5.

Here, in order to supply the hydraulic pressure to the first hydraulic chamber 29 with lubricating oil, the camshaft 2 is provided with a first shaft oil passage 22 which forms an advance control passage extending along the center of the camshaft 2. Has been formed. The hollow bolt 19 is screwed into the shaft oil passage 22 so that the shaft oil passage 2
2 is communicated with the first hydraulic chamber 29 through the central hole 31 of the hollow bolt 19. The inner diameter of the central hole 31 is formed smaller than the inner diameter of the shaft oil passage 22 to form a reduced diameter portion. Further, a part of the outer periphery of the tip portion of the hollow bolt 19 is removed by cutting or the like to form a step portion 21.
An annular recess 23 is formed by the step portion 21 and the inner wall of the shaft oil passage 22. This annular recess 2
Reference numeral 3 serves as a dust trap that captures foreign matter, abrasion powder and the like.

Further, an oil hole 32 is formed in the shaft oil passage 22, and in the vicinity of the oil hole 32, a ball 33 for partitioning the shaft oil passage 22 is provided in the middle of the first shaft oil passage 22. It is provided. The ball 33 allows the oil hole 32 to communicate with only the first hydraulic chamber 29 through the shaft oil passage 22 and the central hole 31.

On the other hand, in order to supply the hydraulic pressure to the second hydraulic chamber 30 with the lubricating oil, the camshaft 2 has a second retard control passage extending parallel to the first shaft oil passage 22.
Shaft oil passage 34 is formed. An oil hole 35 is formed at the tip of the camshaft 2 so as to open to the outer periphery thereof and communicate with the second shaft oil passage 34. Further, an oil hole 36 that connects the oil hole 35 and the second hydraulic chamber 30 is formed in a part of the boss 10 of the timing pulley 5.

Further, in the middle of each hydraulic pressure supply system leading to the head oil passage 6, each hydraulic pressure chamber 2 of the VVT actuator 1 is provided.
A hydraulic control valve (OCV) 37, which is an electromagnetic four-way valve, is provided for controlling the supply of hydraulic pressure to the valves 9 and 30. The OCV 37 includes a head oil passage 6, an oil filter 38, an oil pump 39, and an oil strainer 4.
It is connected to the oil pan 41 through 0. The oil pump 39 is drivingly connected to the engine, and pumps and discharges lubricating oil in conjunction with the operation of the engine. Then, by driving the oil pump 39, the lubricating oil is sucked up from the oil pan 41 via the oil strainer 40. After passing through the oil filter 38, the lubricating oil is supplied to the head oil passage 6 with a predetermined pressure by the operation of the OCV 37. here,
The lubricating oil is supplied to the head oil passage 6 by the OCV 37
Can be adjusted as desired.
A main oil passage 42 is branched between the oil filter 38 and the OCV 37, and the oil passage 42 communicates with an engine body lubrication system 43 including a valve mechanism and a crank mechanism. There is.

When the OCV 37 is moved to the right in the figure, the hydraulic pressure supplied to the head oil passage 6 becomes O.
From the CV 37 through the shaft oil passage 22 to the first hydraulic chamber 2
9 is supplied. By applying this hydraulic pressure to one end of the ring gear 26, the ring gear 26 moves to the second hydraulic chamber 3
The camshaft 2 is twisted while being rotated while being moved in the axial direction against the lubricating oil remaining at zero. As a result,
When the relative position of the camshaft 2 and the timing pulley housing 7 in the rotation direction is changed, the opening / closing timing of the intake valve is advanced.

On the other hand, when the OCV 37 is moved to the left in the figure, the oil pressure supplied to the head oil passage 6 becomes O.
From the CV 37 through the shaft oil passage 34 to the second hydraulic chamber 3
Supplied to zero. By applying this hydraulic pressure to the other end of the ring gear 26, the ring gear 26 is moved to the first hydraulic chamber 2
The camshaft 2 is rotated while being moved in the axial direction against the lubricating oil remaining in 9, and the camshaft 2 is twisted in the opposite direction.
As a result, the relative position of the camshaft 2 and the timing pulley housing 7 in the rotational direction changes, and the opening / closing timing of the intake valve is delayed.

The solenoid 45 of the OCV 37 is driven and controlled by an engine electronic control unit (ECU) 44. Specifically, various sensors are connected to the input side of the ECU 44. In addition, the O
The solenoid 45 of the CV 37 is connected. And
The ECU 44, based on the detection signals from the various sensors,
The state of the engine at that time is indexed and a control signal for driving the solenoid 45 is output.

Next, the operation of the dust trap formed at the tip of the bolt, which is a characteristic part of this embodiment, will be described. Lubricating oil, which is VVT hydraulic oil supplied from the oil pump 39, is guided to the OCV 37 and reaches the vicinity of the center hole 31 of the hollow bolt 19 via the oil hole 32 and the shaft oil passage 22. As shown in FIG. 2, since the central hole 31 is formed to have a small diameter with respect to the shaft oil passage 22, the flow of the supplied lubricating oil is stagnant at this position. Further, at this time, the camshaft 2 is rotating, and accordingly, the lubricating oil itself is also rotating. However, since the foreign matter or wear powder contained in the lubricating oil has a larger specific gravity than the lubricating oil, the centrifugal force caused by this rotation moves the inner peripheral surface of the shaft oil passage 22 as shown by the dotted arrow in the figure. . Further, due to the inertial force acting in the traveling direction of the lubricating oil, the foreign matter or the abrasion powder is captured by the annular recess 23 formed by the step portion 21 and the inner wall of the shaft oil passage 22, that is, the dust trap.

Therefore, foreign matter contained in the lubricating oil is prevented from entering the hydraulic chamber 29. It should be noted that most of the foreign matter contained in the lubricating oil in the oil passage is removed by the oil filter 38 and the like provided in the oil passage, so that the size of the annular recess 23 is set according to the removal ability. It is like this.

The lubricating oil from which foreign substances have been removed by the dust trap passes through the center hole 31, the hydraulic chamber 29, the gap between the seal ring 46 of the ring gear 26 and the cover 8 or the gap between the ring gear 26 and the inner cap 18, It enters the hydraulic chamber 30. Then, the lubricating oil in the hydraulic chamber 30 is guided to the OCV 37 via the oil hole 36 and the shaft oil passage 34, and is further discharged to the oil pan 41.

As described in detail above, since the dust trap formed by the annular recess 23 removes foreign matter in the lubricating oil, the meshing portion between the ring gear 26 and the cover 8 or the ring gear 26 and the inner cap 18 is removed. Foreign matter is prevented from entering the meshing part of the gear, and the sticking or locking of the gear is prevented.

The present invention is not limited to the above-described embodiment, but may be implemented as follows with a part of the configuration appropriately modified without departing from the spirit of the invention. (1) In the above-described embodiment, the annular recess 23 is formed by the step portion 21 in which a part of the outer periphery of the end of the hollow bolt 19 is removed by cutting or the like and the inner wall of the shaft oil passage 22.
As shown in FIG. 3, an annular groove 50 may be formed in the shaft oil passage 22 by cutting or the like to form an annular recess. The annular groove 50 is formed along the outer circumference of the hollow bolt at a position close to the tip of the hollow bolt on the inner wall of the advance angle control passage, and further opens into the passage. With this configuration, the same effect as described above can be obtained.

(2) In the above-described embodiment, the pressure chambers 29 and 30 are provided on both sides of the ring gear 26 to drive them by the pressure balance between the two. However, a spring is provided between the ring gear 26 and the timing pulley 5. It may be so arranged that only the pressure in one pressure chamber is changed.

(3) In the above embodiment, both the inner and outer teeth 27, 28 of the ring gear 26 are helical teeth, but only one of the inner and outer teeth 27, 28 may be helical teeth. .

[0032]

As described above in detail, according to the present invention, it is possible to provide a highly reliable valve timing control device for an internal combustion engine which can remove foreign matter at low cost.

[Brief description of drawings]

FIG. 1 is a sectional view mainly showing a valve timing control device including a VVT actuator in an embodiment embodying the present invention.

FIG. 2 is an enlarged cross-sectional view showing the vicinity of a bolt for jointly fastening the VVT actuator and the cam shaft shown in FIG.

FIG. 3 is a cross-sectional view showing the main parts of another embodiment of the present invention.

[Explanation of symbols]

2 ... Cam shaft, 5 ... Timing pulley, 19 ... Hollow bolt, 21 ... Step portion, 22 ... (constituting control passage)
Shaft oil passage, 23 ... annular recess, 26 ... ring gear, 2
7, 28 ... Tooth, 29, 30 ... Hydraulic chamber, 31 ... Central hole (constituting reduced diameter portion), 34 ... Shaft oil passage (constituting control passage), 50 ... Annular groove.

Claims (1)

[Claims] 1. A pulley provided on the outer circumference of a valve-driving cam shaft of an internal combustion engine, and a pulley interposed between the cam shaft and the pulley,
A cylindrical ring gear having teeth on the inner and outer peripheral surfaces, and at least one of which is a helical tooth, and a fluid from a pressurized fluid supply source is introduced into pressure chambers provided at both ends of the ring gear, and the fluid is It is equipped with a pair of control passages for acting on both ends of the ring gear, and the ring gear is moved in the axial direction of the camshaft by the biasing force of the fluid pressure from the pressurized fluid supply source to release the driving force of the pulley. In a variable valve timing control device in which the teeth are transmitted to the camshaft and the rotational phase of the pulley and the camshaft is changed to adjust the opening / closing timing of the valve, the helical teeth in the control passage are The control passage communicating with the pressure chamber includes a passage along the axial direction of the camshaft, and the passage is reduced in diameter with respect to the pressurized fluid supply source side to cause stagnation in the fluid. Reduced part An annular recess is formed near the inlet of the reduced diameter portion on the pressurized fluid supply side so as to catch foreign matter in the fluid along the inner circumference of the passage along the camshaft. A valve timing control device for an internal combustion engine.