JPH04105910U - Valve actuation device for multi-cylinder engines - Google Patents

Abstract

(57) [Summary] [Purpose] The purpose is to alleviate engine torque fluctuations caused by cam switching operations in a valve operating device for a multi-cylinder engine in which a cam switching mechanism is provided for each cylinder. [Structure] A hydraulic passage 27 is provided that leads hydraulic pressure to the hydraulic chamber 25 of the cam switching mechanism 1 of another cylinder via the hydraulic chamber 25 of the cam switching mechanism 1 of one cylinder, and one end of this hydraulic passage 27 is connected to the hydraulic chamber 25 of the cam switching mechanism 1 of one cylinder. A return spring 24 is provided which is opened in the middle of the fitting hole 29 of the piston 21 and urges the hydraulic piston 29 to the initial position, and a throttle hole 30 is provided which allows the hydraulic fluid in the hydraulic passage 27 to escape.

Description

[Detailed explanation of the idea]

0001

[Industrial application field]

The present invention is a valve actuation system for a multi-cylinder engine, especially one that can This relates to switching between several cams.

0002

[Conventional technology]

Traditionally, in order to improve engine output performance, intake valves or or by changing the lift characteristics of the exhaust valve, thereby adjusting the intake and exhaust timing or It is known to control the amount of intake and exhaust.

0003 For example, in Japanese Patent Application Laid-Open No. 62-294709, a valve lift is introduced in a multi-cylinder engine. A cam switching machine that switches between two cams with different characteristics and the cam involved in opening and closing the valve. A mechanism is provided for each cylinder, and an oil passage communicating with the cam switching mechanism of each cylinder is provided. Cam switching is performed for each cylinder in response to pressurized hydraulic fluid supplied through the passage. are disclosed.

0004

[Problem that the idea aims to solve]

By the way, with such conventional devices, when switching the cam, the torque generated by the engine is In order to prevent large changes in the torque generated by each cam, the It was necessary to switch at a turning point.

[0005] Therefore, each cam imposes restrictions on the setting of torque characteristics, and for example, one cam In order to improve fuel efficiency, the valve operating angle is set to a small value for low-load operation. In addition, the other cam is set to a relatively large amount that increases the generated torque in response to high-load operation. If a large valve operating angle is set, a large torque change will occur when switching each cam. A problem arose.

[0006] In addition, the cam is set to switch at an operating point with little torque change. Even in cases where the valve actuating device deteriorates over time, the torque change when switching the cam increases. It was possible.

[0007] This idea was devised by focusing on these conventional problems, and the cam switching operation was The purpose of this invention is to provide a valve actuation device that alleviates engine torque fluctuations caused by .

[0008]

[Means to solve the problem]

This invention uses multiple cams with different valve lift characteristics for a common valve. , a cam switching mechanism that switches the cam involved in opening and closing the valve via a hydraulic piston. In the valve actuation device of a multi-cylinder engine, which is provided for each cylinder, a cam switching machine for one cylinder is used. Hydraulic passage that leads hydraulic pressure to the hydraulic chamber of the cam switching mechanism of another cylinder via the hydraulic chamber of the mechanism. A hydraulic piston is installed by opening one end of this hydraulic passage midway through the fitting hole of the hydraulic piston. The structure opens and closes by the sliding of the piston, and the hydraulic piston is biased to the initial position. In addition to providing a return spring to prevent leakage, a throttle hole is provided to release hydraulic fluid in the hydraulic passage establish.

[0009]

[Effect]

When the hydraulic pressure guided to the hydraulic piston is low, the biasing force of the return spring The hydraulic piston is held in the initial position, and the hydraulic passage that opens in the middle of the fitting hole is closed. Closed by a hydraulic piston.

0010 In one cylinder, when the hydraulic pressure introduced to the hydraulic piston is increased, the hydraulic piston As the stone slides from its initial position, the cam is switched and A hydraulic passageway opening into the fitting hole is opened. In this way, the hydraulic piston is The cam functions as a hydraulic on-off valve to adjust the hydraulic pressure led to the cam cylinder mechanism of the cylinder. After the cam of a cylinder has been switched, the cam of another cylinder is switched, and each cylinder Cam switching is performed with a time difference.

[0011] Therefore, the torque generated by the engine changes stepwise with a time difference between each cylinder. , even if the cam is switched at operating points where the generated torque is significantly different from each other. Even if the cam is switched, the torque fluctuation that occurs when switching the cam can be alleviated.

0012 When the hydraulic pressure introduced into each hydraulic chamber is adjusted to a low level again, the return spring is attached. As the hydraulic piston slides a certain stroke due to force, its mating hole One end of the hydraulic passage that opens at The hydraulic piston returns to its initial position by contracting each hydraulic chamber while letting hydraulic oil escape from the throttle hole. The cams are switched for each cylinder.

[0013]

【Example】

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

[0014] In Figure 1, 1 indicates three valve lift characteristics with different valve lift characteristics depending on the engine operating conditions. This is a cam switching mechanism in which the cam is switched, and this cam switching mechanism 1 is used to switch each air of the engine. It is provided for each cylinder.

[0015] The cam switching mechanism 1 has one main rod whose swinging tip 2a abuts on two valves. A rocker arm 2 is swingably supported by each cylinder via a common rocker shaft 5. Two sub-blocks are installed on the main rocker arm 2 of the Rocker arms 3 and 4 are swingably supported via a sub-rocker shaft 7.

[0016] The main rocker arm 2 is connected to the partial load cam via a roller follower 6. This is followed by the urging force of a valve spring (not shown). Each sub rocker arm 3, 4 is a low-speed, high-load cam whose profile gradually increases and a high-speed, high-load cam. Each is followed by the biasing force of a lost motion spring (not shown).

[0017] The main rocker arm 2 has a piston 21 extending between it and the sub rocker arm 4. A coupling pin 22 is slidably fitted, and a hydraulic chamber 25 is provided at one end of the piston 21. A return spring is attached to one end of the coupling pin 22 via a spring cap 23. 24 is interposed.

[0018] When the hydraulic pressure introduced into the hydraulic chamber 25 is low, the return spring 24 is biased. The force causes the piston 21 and the connecting pin 22 to come into contact with the stopper 28 as shown by the solid line in FIG. By being held at the initial position, the sub rocker arm 4 moves to the main rocker arm. The main rocker arm 2 has a small profile without being restrained against the arm 2. Opens and closes the valve following the partial load cam.

[0019] When the hydraulic pressure introduced into the hydraulic chamber 25 is increased, it resists the return spring 24. The piston 21 and the connecting pin 22 are connected to the sub-rocker arm as shown by the two-dot chain line in 4 and the main rocker arm 2 into the restraining position. This is it The sub rocker arm 4 is integrated with the main rocker arm 2 and swings, and the main rocker arm The rocker arm 2 rises above the small-profile part-load cam and also The rocker arm 3 lifts up from the low-speed, high-load cam and passes through the sub-rocker arm 4. The valve opens and closes following the high-speed, high-load cam with the largest profile.

[0020] The hydraulic passage 26 that leads the working hydraulic pressure to the hydraulic chamber 25 is also shown in FIGS. 2, 3, and 4, respectively. As shown, the through hole 33 formed in the main rocker arm 2 and the rocker shaft 5 a groove 32 formed on the outer peripheral surface of the rocker shaft 5; and a through hole 31 opened at one end of the rocker shaft 5. formed by.

[0021] As shown in Figure 5, this is the gist of this invention. The hydraulic chamber of the cam switching mechanism 1 of another cylinder via the hydraulic chamber 25 of the cam switching mechanism 1 of the cylinder. 25 is provided with a hydraulic passage 27 for guiding hydraulic pressure, and one end of this hydraulic passage 27 is connected to the piston 2. A structure in which the fitting hole 29 of No. 1 is opened in the middle and opened and closed by sliding of the piston 21. shall be.

[0022] The hydraulic passage 27 is connected to a through hole 41 formed in the main rocker arm 2 and the rocker shaft. The groove 42 formed on the outer circumferential surface of the foot 5 is always in communication with the hydraulic chamber 25 of the adjacent cylinder. It is formed by a through hole 33. The through hole 41 is located inside the fitting hole 29 of the piston 21. When the piston 21 is fitted to the circumferential surface and is in the unrestricted position as shown by the solid line in FIG. closed and opened when the piston 21 is in the locked position as shown by the two-dot chain line in FIG. , the hydraulic chambers 27 of the two cylinders are communicated with each other.

[0023] In order to release the hydraulic oil in the hydraulic passage 27, a hole is inserted between the through hole 26 of the sub-rocker arm 4. A throttle hole 30 is formed therein and opens to the cam follower surface. Opening diameter of throttle hole 30 is formed to become smaller stepwise in the order of the first cylinder, third cylinder, fourth cylinder, and second cylinder.

[0024] Next, the effect will be explained.

[0025] When the hydraulic pressure introduced into the hydraulic chamber 25 of the first cylinder is increased, the piston 21 is initially The cam slides from the position to the locked position, and the cam is switched in the first cylinder. , the hydraulic passage 27 opening into the fitting hole 29 is opened, and the hydraulic oil flows as shown by the arrow in the figure. Then, it is guided to the hydraulic chamber 25 of the second cylinder via the hydraulic chamber 25 of the first cylinder. like this The piston 21 acts as a hydraulic opening/closing valve between each cylinder, and the switching of the cam of the first cylinder is performed. After finishing, the cam of the second cylinder is switched, and the time difference is sequentially changed to the third and fourth cylinders. The cams are switched with .

[0026] Therefore, the torque generated by the engine changes stepwise with a time difference between each cylinder. , even if the cam is switched at operating points where the generated torque is significantly different from each other. Even if the cam is switched, the torque fluctuation that occurs when switching the cam can be alleviated.

[0027] When each piston 21 is in the restrained position, hydraulic oil flows from each throttle hole 30 into the camshaft. Flows onto the lower and lubricates the sliding contact area with the cam, reducing friction. .

[0028] When the hydraulic pressure introduced into the hydraulic chamber 25 of the first cylinder is adjusted to a low level again, the return As the piston 21 slides by a certain stroke due to the urging force of the spring 24, Therefore, one end of the hydraulic passage 27 that opens into the fitting hole 29 is closed, but in this state As the hydraulic oil in the hydraulic passage 27 is released through the throttle hole 30, the oil in the second cylinder is The pressure chamber 25 is contracted and each piston 21 slides to the initial position, and the third cylinder and fourth cylinder Similarly, in the cylinder, each piston 21 slides to its initial position and the cam is switched. Ru. The opening diameter of the throttle hole 30 is stepped in the order of the 1st cylinder, 3rd cylinder, 4th cylinder, and 2nd cylinder. Since the piston 21 is formed small, the sliding speed of the piston 21 between each cylinder is reduced. However, the above cams are switched in the order of 1st cylinder, 3rd cylinder, 4th cylinder, and 2nd cylinder. This can alleviate torque fluctuations that occur when switching cams.

[0029] A piston 11 is installed between the main rocker arm 2 and the sub rocker arm 3. A coupling pin 12 is slidably fitted, and a hydraulic chamber 15 is provided at one end of the piston 11. A return spring is attached to one end of the coupling pin 12 via a spring cap 13. 14 is interposed. Return spring 1 due to hydraulic pressure guided to hydraulic chamber 15 When the piston 11 and the connecting pin 12 slide against the 3 is restrained against the main rocker arm 2, and the main rocker arm 2 is It floats up from the partial load cam with a small roll, and the pro Opens and closes the valve following the low-speed, high-load cam with a large feel.

[0030] Regarding this sub-rocker arm 3, the hydraulic chamber 1 of the cam switching mechanism 1 of one cylinder A hydraulic passage 1 that leads hydraulic pressure to the hydraulic chamber 15 of the cam switching mechanism 1 of another cylinder via 5. 7, and one end of this hydraulic passage 17 is opened in the middle of the fitting hole 19 of the piston 11. The cylinders are opened and closed by the sliding movement of the piston 11, and each cylinder has a time difference. The cam is then switched.

[0031]

[Effect of the idea]

As explained above, the present invention is a multi-cylinder engine equipped with a cam switching mechanism for each cylinder. In a valve actuation device, one cylinder is connected to another cylinder via the hydraulic chamber of the cam switching mechanism. A hydraulic passage is provided to guide hydraulic pressure into the hydraulic chamber of the cam switching mechanism, and one end of this hydraulic passage is It is opened in the middle of the fitting hole of the hydraulic piston and is opened and closed by the sliding of the hydraulic piston. The hydraulic piston is constructed with a return spring that biases the hydraulic piston to its initial position. In addition, by providing a throttle hole to release the hydraulic fluid in the hydraulic passage, Even if the cam is switched at operating points with significantly different torques, the engine Torque changes stepwise for each cylinder group or cylinder, and the error that occurs when switching cams It can reduce engine torque shock and improve the drivability of automobiles, etc. As a result, the degree of freedom in setting the cam is increased, and the fuel efficiency and output performance of the engine can be improved. Both can be improved.

[Brief explanation of drawings]

FIG. 1 is a plan view of a cam switching mechanism showing an embodiment of the present invention.

FIG. 2 is a cross-sectional view taken along line AA in FIG. 1;

FIG. 3 is a longitudinal cross-sectional view of the rocker shaft.

4 is a cross-sectional view of the rocker shaft taken along line BB in FIG. 3; FIG.

FIG. 5 is a configuration diagram of the valve operating device.

[Explanation of symbols]

1 Cam switching mechanism 2 Main rocker arm 3 Sub rocker arm 4 Sub rocker arm 5 Rocker shaft 11 Piston 14 Return spring 15 Hydraulic chamber 17 Hydraulic passage 19 Fitting hole 21 Piston 24 Return spring 25 Hydraulic chamber 27 Hydraulic passage 29 Fitting hole 30 Throttle hole

Continuation of front page (72) Creator Shigeru Sakuragi 2 Takaracho, Kanagawa-ku, Yokohama-shi, Kanagawa Prefecture Nissan Within Jidosha Co., Ltd.

Claims (1)

[Scope of utility model registration request] 1. A multi-cylinder engine comprising, for each cylinder, a plurality of cams having different valve lift characteristics for a common valve, and a cam switching mechanism that switches the cams involved in opening and closing the valves via a hydraulic piston. In a valve actuation device, a hydraulic passage is provided to guide hydraulic pressure from the hydraulic chamber of the cam switching mechanism of one cylinder to the hydraulic chamber of the cam switching mechanism of another cylinder, and one end of this hydraulic passage is connected to the fitting of the hydraulic piston. The hole is opened in the middle and opened and closed by the sliding of the hydraulic piston, and a return spring is provided to urge the hydraulic piston to its initial position, as well as a throttle hole to release the hydraulic fluid in the hydraulic passage. Valve actuation device for multi-cylinder engines.