JP2002309917A - Variable valve lift mechanism for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To vary a relative position relation between a cam and a valve immediately when a switch valve is operated to vary a relative position relation between the cam and the valve. SOLUTION: A variable valve lift mechanism comprises a cam 2 to lift the valve 1; a cam shaft 3 coupled to the cam; fluid pressure chambers 7 and 8 to receive fluid to feed a pressure to the cam shaft; a pump 6 to feed fluid with a pressure to a fluid pressure chamber; and a switch valve 5 situated in a fluid flow passage between the fluid pressure chamber and the pump to control the presence of introduction of fluid to the fluid chamber. By displacing the cam shaft from the valve by feeding a pressure to the cam shaft by fluid in the fluid pressure chamber, a relative position relation between the cam shaft and the valve is varied, and this variation can vary the lift characteristics of the valve. The fluid pressure chamber, the pump, and the switching valve are contained in one housing 17 and integrally formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a variable valve lift mechanism for an internal combustion engine.

[0002]

2. Description of the Related Art A mechanism for lifting an intake valve of an internal combustion engine, the mechanism of which is capable of changing its lift characteristics is known, for example, from Japanese Patent Application Laid-Open No. 9-280019. The mechanism here uses hydraulic pressure to change the relative positional relationship between the cam and the intake valve, thereby changing the lift characteristics of the intake valve and deceivably controlling the amount of air drawn into the combustion chamber. ing. The mechanism described in the above publication generally includes a hydraulic pump for supplying hydraulic pressure, a hydraulic chamber for receiving hydraulic oil for changing a relative positional relationship between a cam and an intake valve, and a hydraulic chamber for receiving hydraulic oil. A switching valve for switching between supply and non-supply of hydraulic pressure to the hydraulic chamber, and changing the relative positional relationship between the cam and the intake valve by switching between supply and non-supply of hydraulic pressure to the hydraulic chamber by the switch valve. be able to.

[0003]

The hydraulic pump, the hydraulic chamber, and the switching valve are connected to each other via a hydraulic passage, but are arranged at a certain distance from each other. Even if the changeover valve is operated to change the relative position between the cam and the intake valve due to the hydraulic pressure, it takes time to introduce hydraulic oil from the hydraulic pump into the hydraulic chamber. That is, if the distance between the hydraulic pump and the hydraulic chamber is long, even if hydraulic oil is introduced from the hydraulic pump into the hydraulic chamber, the relative positional relationship between the cam and the intake valve is not immediately changed. This is generally true for mechanisms utilizing other fluids, including hydraulic fluids. In view of such circumstances, an object of the present invention is to change the relative positional relationship between the cam and the valve as soon as the switching valve is operated to change the relative positional relationship between the cam and the valve.

[0004]

According to a first aspect of the present invention, there is provided a cam for lifting a valve, a camshaft connected to the cam, and a pressure for supplying pressure to the camshaft. A fluid pressure chamber for receiving the fluid, a pump for pumping the fluid to the fluid pressure chamber, and a fluid between the fluid pressure chamber and the pump for controlling whether or not the fluid is introduced into the fluid pressure chamber. A switching valve disposed in the flow path, wherein a pressure is supplied to the camshaft by the fluid in the fluid pressure chamber to displace the camshaft with respect to the valve, so that a relative position between the cam and the valve is provided. In a variable valve lift mechanism for an internal combustion engine in which the relationship is changed and thereby the valve lift characteristics are changed, the fluid pressure chamber, the pump and the switching valve are housed and integrated in one housing. That is, according to this, since the fluid pressure chamber, the pump, and the switching valve are housed and integrated in one housing, the distance between the fluid pressure chamber, the pump, and the switching valve is shortened. I have.

In the second invention, in the first invention,
The valve is an intake valve for controlling whether air is introduced into the combustion chamber of the internal combustion engine. In a third aspect based on the first aspect, the fluid is oil. According to a fourth aspect, in the first aspect, the lift characteristic of the valve is changed by displacing the camshaft with respect to the valve in the axial direction thereof, and the valve body in which the switching valve is disposed is provided. The switching valve is a valve that controls whether or not fluid is introduced into the fluid pressure chamber by sliding, and the switching valve is arranged such that the sliding direction of the valve body is parallel to the axial direction of the camshaft.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a variable valve lift mechanism according to the present invention will be described below with reference to the drawings. In FIG. 1, reference numeral 1 denotes an intake valve of an internal combustion engine mounted on an automobile, reference numeral 2 denotes a cam for reciprocating the intake valve 1 as shown by an arrow A, and reference numeral 3 denotes a cam to which a cam 2 is attached. It is a shaft. The cam 2 has a nose 2 ′ for lifting the intake valve 1. The outer peripheral surface of the nose portion 2 ′ of the cam 2 is inclined along the axial direction of the camshaft 3. Accordingly, when the camshaft 3 is displaced with respect to the intake valve 1 along the axial direction so that the relative positional relationship between the cam 2 and the intake valve 1 changes as described later, the cam 2 is moved to the intake valve 1. Is changed, and thus the amount of air taken into the combustion chamber (not shown) is controlled.

The variable valve lift mechanism of the present invention, in this embodiment, the variable intake valve lift mechanism generally includes a lift characteristic changing mechanism 4, a spool valve 5, and a hydraulic pump 6. The lift characteristic changing mechanism 4 includes two hydraulic chambers 7 and 8 for receiving hydraulic oil. These hydraulic chambers 7 and 8 are separated by a hydraulic panel 9 attached to an end of the camshaft 3. Therefore, when hydraulic oil is introduced into the hydraulic chamber 7, the camshaft 3 is displaced in the direction of arrow B1. On the other hand, when hydraulic oil is introduced into the hydraulic chamber 8, the camshaft 3 is displaced in the direction of arrow B2. That is, according to the present embodiment, the direction in which the camshaft 3 is displaced is controlled by controlling whether hydraulic oil is introduced into the hydraulic chamber 7 or hydraulic oil is introduced into the other hydraulic chamber 8. By introducing hydraulic oil into one of the hydraulic chambers 7, 8, the camshaft 3 is displaced in the axial direction with respect to the intake valve 1, and thus the cam 2 is also moved with respect to the intake valve 1 by the camshaft 3. Therefore, the lift characteristic of the intake valve 1 is changed by the lift characteristic changing mechanism.

The spool valve 5 includes a spool 10, an electromagnetic solenoid 11 for moving the spool 10 in the direction of arrow C1, a coil spring 16 for urging the spool 10 to move the spool 10 in the direction of arrow C2, A pair of openings 7b, 8b respectively connected to hydraulic paths 7a, 8a communicating with the respective hydraulic chambers 7, 8, two return openings 12, 14, and these return openings 12, 1
And a pump opening 13 located between the four. The return openings 12 and 14 are respectively provided with return hydraulic paths 12a and 1
4a. On the other hand, the pump opening 13 is connected to a pump hydraulic passage 13a. The hydraulic pump 6 is arranged in the pump hydraulic path 13a. A return passage 13c extends from the hydraulic pump 6. The return passage 13c is connected to the return hydraulic passage 13d. Return passage 13
A relief valve 6 'is arranged at c. The relief valve 6 ′ opens when the pressure downstream of the hydraulic pump 6 becomes equal to or higher than a predetermined pressure, and returns to the return passage 13 c and the return hydraulic passage 13 d.
The hydraulic oil is returned to the hydraulic oil tank 15 via the. The return hydraulic paths 12a and 14a are respectively
b, 14b. Pump hydraulic path 13a
Is connected to the pump hydraulic path 13b. Further, these hydraulic paths 12b, 13b, 14b are connected to a hydraulic oil tank 15.

Next, the operation of the variable intake valve lift mechanism of this embodiment will be briefly described. When electric power is supplied to the electromagnetic solenoid 11 and the spool 10 is moved by the electromagnetic solenoid 11 in the direction of arrow C1 against the urging force of the coil spring 16, the hydraulic chamber 8 moves the spool valve 5 (specifically, the hydraulic path 8a, It is connected to the hydraulic pump 6 via the opening 8b, the pump opening 13, and the pump hydraulic passage 13a). Therefore, the hydraulic pump 6 introduces hydraulic oil from the hydraulic oil tank 15 into the hydraulic chamber 8. On the other hand, the hydraulic chamber 7 has a spool valve 5
(Specifically, the hydraulic path 7a, the opening 7b, the return opening 12,
Return hydraulic path 12b via return hydraulic path 12a)
It is made to communicate with. Therefore, the hydraulic oil in the hydraulic chamber 7 is returned to the hydraulic oil tank 15. According to this, the camshaft 3 is displaced in the direction of the arrow B2, and the relative positional relationship between the cam 2 and the intake valve 1 changes correspondingly, so that the lift characteristic of the intake valve 1 is reduced. Can be changed.

On the other hand, the power supply to the electromagnetic solenoid 11 is stopped, and the spool 10
Is moved in the direction of arrow C2.
Is connected to the hydraulic pump 6 via the spool valve 5 (specifically, the hydraulic path 7a, the opening 7b, the pump opening 13, and the pump hydraulic path 13a). Therefore, the hydraulic pump 6 introduces hydraulic oil from the hydraulic oil tank 15 into the hydraulic chamber 7. On the other hand, the hydraulic chamber 8 is provided with a spool valve 5 (specifically, a hydraulic path 8a, an opening 8b,
It communicates with the return hydraulic passage 14b via the return opening 14 and the return hydraulic passage 14a). Therefore, the hydraulic oil in the hydraulic chamber 8 is returned to the hydraulic oil tank 15. According to this, the camshaft 3 is displaced in the direction of the arrow B1, and the relative positional relationship between the cam 2 and the intake valve 1 changes correspondingly, so that the lift characteristic of the intake valve 1 is reduced. Can be changed. The lift characteristic of the intake valve 1 is determined so that an amount of air determined for each engine operation state is sucked into the combustion chamber.

As shown in FIG. 1, in this embodiment, a lift characteristic changing mechanism 4, a spool valve 5, and a hydraulic pump 6, which are main components of the variable intake valve lift mechanism, are provided in a single housing 17. Is housed. That is, according to the present embodiment, the lift characteristic changing mechanism 4, the spool valve 5, and the hydraulic pump 6 are integrated. Therefore, the length of the hydraulic path connecting these elements is very short. Generally, if the distance between the hydraulic pump 6 and the lift characteristic changing mechanism 4 for finally supplying hydraulic pressure is long, the hydraulic pump 6 tries to introduce hydraulic oil into the lift characteristic changing mechanism 4 and then actually increases the lift characteristic. It takes a long time for the hydraulic oil to reach the change mechanism 4. That is, if the distance from the hydraulic pump 6 to the lift characteristic changing mechanism 4 is long, a control delay occurs. However, if the components of the intake valve lift mechanism are integrated as in the present embodiment, no control delay occurs, and therefore, desired control is performed accurately and quickly.

In the lift characteristic changing mechanism of this embodiment, the direction of displacing the camshaft 3, that is, the axial direction of the camshaft 3, and the spool 10 of the spool valve 5 as a switching valve for controlling the introduction of hydraulic oil. Is almost parallel to the moving direction. According to this, since the flow path lengths of the hydraulic paths 7a and 8a that communicate the openings 7b and 8b of the spool valve 5 and the hydraulic chambers 7 and 8 are shortened, the present embodiment also prevents the control delay from occurring in this respect. Has become.

In the above-described embodiment, the mechanism for lifting the intake valve, which is capable of changing the lift characteristic of the intake valve, has been described as an example. However, the mechanism for lifting the exhaust valve of the internal combustion engine is described. Accordingly, the present invention can be applied to a mechanism capable of changing the lift characteristics of the exhaust valve. Therefore, in general, the present invention is applicable to a mechanism for lifting a valve of an internal combustion engine, which mechanism can change the lift characteristic of the valve.
Further, in the above-described embodiment, the hydraulic oil is used to supply the pressure for displacing the camshaft, but another fluid may be used.

[0014]

According to the present invention, the fluid pressure chamber, the pump and the switching valve are housed and integrated in one housing, so that the fluid pressure chamber, the pump and the switching valve are integrated. The distance is getting shorter. Therefore, the switching valve is operated, and the fluid is immediately introduced into the fluid pressure chamber by the pump. That is, as soon as the switching valve is operated to change the relative positional relationship between the cam and the valve, the relative positional relationship between the cam and the valve is changed.

[Brief description of the drawings]

FIG. 1 is a view showing a variable intake valve mechanism to which the present invention is applied.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Intake valve 2 ... Cam 3 ... Camshaft 4 ... Hydraulic supply mechanism 5 ... Spool valve 6 ... Pump 17 ... Housing

Continued on the front page F-term (reference) 3G018 AB07 AB16 BA04 BA09 BA34 CA19 DA03 DA05 DA49 DA54 DA55 DA57 DA75 DA77 DA83 FA01 FA06 FA07 GA03 GA14 3G092 AA01 AA11 AA12 AB02 BA01 DA01 DA03 DA04 DA06 DD03 DF01 DF04 DF09 EA05 EA02 EA05 FA03 FA04 FA05 FA07 FA09 FA11 FA50 GA03 HA01Z HA13Z HB01Z HE01Z HE03Z HF09Z

Claims (4)

[Claims] 1. A cam for lifting a valve, a camshaft connected to the cam, a fluid pressure chamber for receiving fluid for supplying pressure to the camshaft, and pumping fluid to the fluid pressure chamber. And a switching valve disposed in a fluid flow path between the fluid pressure chamber and the pump to control whether or not fluid is introduced into the fluid pressure chamber. Changing the relative positional relationship between the cam and the valve by supplying pressure to the camshaft with the fluid in the chamber and displacing the camshaft with respect to the valve,
A variable valve lift mechanism for an internal combustion engine which changes the lift characteristics of a valve, wherein the fluid pressure chamber, the pump and the switching valve are housed and integrated in one housing. Variable valve lift mechanism. 2. The variable valve lift mechanism for an internal combustion engine according to claim 1, wherein the valve is an intake valve for controlling whether air is introduced into a combustion chamber of the internal combustion engine. 3. The variable valve lift mechanism for an internal combustion engine according to claim 1, wherein the fluid is oil. 4. The lift characteristic of the valve is changed by displacing the camshaft with respect to the valve in the axial direction thereof, and the valve body in which the switching valve is disposed slides, whereby the fluid is increased. 2. A valve for controlling whether or not a fluid is introduced into a pressure chamber, wherein the switching valve is disposed such that a sliding direction of a valve body is parallel to an axial direction of a camshaft. A variable valve lift mechanism for an internal combustion engine according to claim 1.