JPS60169615A - Seat damping device for exhaust valve - Google Patents

Abstract

PURPOSE:To seat an exhaust valve slowly by poviding a cushion area at the cylinder bottom section of actuator in hydraulically driven exhaust valve and releasing hydraulic pressure from cushion area through a variable restrictor. CONSTITUTION:A cushion area 16 is formed between the bottom 15 of cylinder for driving an actuator piston 1 coupled with an exhaust valve and working oil port 4. The position of cushion changeover spool 6 is controlled with correspondence to the position of piston 1. Through motion of said spool 6, the pilot check valves 9, 13 are opened sequentially to release working oil from the cushion area 16 through variable restrictors 8, 12. Consequently, seating of exhaust valve is braked resulting in slow seating.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a seating damping device for a hydraulic exhaust valve drive device for a diesel engine.

Conventional hydraulically driven exhaust valve seating damping is.

A piston cushion provided in a hydraulic cylinder, s
It is a direct one with 4 reams, and the mechanism is
Figures (a) and (b) show K. In this case, a cushion is provided on the exhaust valve drive cylinder. Therefore, the following drawbacks remain in the conventional mechanism. Note that the arrow a in Figure 9 indicates the flow to the cam drive hydraulic cylinder, the arrow indicates the communication port when air is splashed,
Arrow C indicates the flow of scavenging external force, d indicates the seating position, and e indicates the flow of exhaust air.

(1) During the exhaust valve closing cycle, the piston 01 driven by the exhaust valve return spring 04 moves to the cushion g I
When moving to J-mu 02, 9 hydraulic oil is trapped, so the speed of exhaust valve 03 suddenly decelerates, and in the exhaust valve seating position, the mechanism enables valve closing operation with less impact, but the cushion? The damping by the ream was too effective and the exhaust valve could not be completely closed in a timely manner at the seating position of the camshaft.

It essentially has a mechanism that reduces efficiency due to combustion air leaking from the exhaust valve during the compression stroke of the internal combustion engine.

(2) Depending on the adjustment of cushion volume 02, it is possible to achieve a critical condition in which the exhaust valve seating position and timing almost match, but if the exhaust valve seats due to insufficient damping due to changes in usage conditions, the exhaust valve 03 will be seated too tightly. Impact may result in damage or shortened lifespan.

An object of the present invention is to focus on the above-mentioned points, and to provide a seated damping device that can not only close the exhaust valve in a timely and reliable manner, but also alleviate impact on the seat of the exhaust valve by realizing a multi-stage damping system. .

In this case, damage and short life of parts can be improved.

Its features include a cushion area formed between the cylinder bottom of the exhaust valve's hydraulic actuator and the hydraulic oil port, and a multi-stage cushion provided in the cushion area that is sequentially activated by the movement of the piston of the hydraulic actuator. The switching spool, which is provided corresponding to the switching spool and driven by the switching spool, is connected to the pilot check valve 9 and the pilot check valve A, which generates a multi-stage polygonal damping resistance in the flow, and which is driven by the switching spool. It is equipped with a variable throttle valve that releases damping.

In this case, the multi-stage damping device minimizes the shock of the exhaust valve and ensures a reliable closing operation within the timing.

The present invention can be applied to a hydraulically driven supply and exhaust valve mechanism for a diesel engine.

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

FIG. 2 is an explanatory diagram showing an apparatus according to an embodiment of the present invention.

In the figure, 1 is a piston of a hydraulic actuator that moves in conjunction with the exhaust valve, 2 is a cylinder section, 3 is a cam-driven hydraulic actuator, and 4 is a hydraulic oil holder.

5 is an oil supply port in the cushion volume, 6 is a multi-stage cushion (Figure 2 shows a two-stage mechanism) switching spool,
7 is the sleeve, 8 is the hydraulic oil relief variable throttle valve of the Kupplan volume, 9 is the pilot check valve for switching the hydraulic oil in conjunction with the spool position, 10 is the pilot valve supply hydraulic boat, 11 is the System pump for pilot valve oil supply, 12 is the second stage variable throttle valve, 13 is its pilot check valve, and 14 is for supplying hydraulic oil into the cushion volume and driving the piston when the exhaust valve is opened. This is a check valve. In addition, 15 is the cylinder bottom.

16 is the cushion volume, 201d, hm, 2
1 is a tank.

Explain compositional relationships. The timing at which the exhaust stroke of the internal combustion engine ends and the exhaust valve is closed is determined by the intake cycle of the cam-driven hydraulic actuator 3. Exhaust valve return spring (
04) In Figure 1, the force causes the piston 1 to move to the hydraulic oil port 1-4.
The oil in the actuator is returned to the cam-driven hydraulic actuator 3 with almost no resistance. On the other hand, when the land of the piston 1 moves completely across the hydraulic oil se -) 4 into the volumetric volume, the cushion switching spool 6
is pressed, and the oil pressure of the system pump 11 is applied to the pilot valve of the Moilot check valve 9, so the oil in the trapped Kupplan volume passes through the pilot check valve 9 and is resisted by the throttle valve 8. Return to tank. During this time, the piston 1 and the exhaust valve 03 (see FIG. 1) are moderately decelerated.

1. When the piston 1 moves close to the bottom 16 of the cylinder section 2, the shoe 7 switchover spool 6 simultaneously operates the pilot valve of the pilot check valve 13, and the oil in the cushion & IJ is drained. Throttle valves 8 and 12
Return to the tank. Therefore, the resistance of the piston 1 before it is decelerated and stopped is reduced (damping is released), and the piston 1 moves near the bottom 16 due to the small external force of the exhaust valve scavenging air force, and the exhaust valve is securely seated on the shock t-s.

On the other hand, when the exhaust valve is opened, high-pressure hydraulic oil is supplied from the check valve 14 through the oil supply hoard 5 in order to push the piston 1 out of the cushion volume.

The functions and effects of the above configuration will be described.

The behavior and effects of the piston 1 in the hydraulic oil cushion volume in which the hydraulic oil N-4 is provided above the cylinder bottom will be explained.

State 1 to state 3 in Fig. 3 show the states of the multi-stage cushion (Fig. 2 shows a two-stage mechanism) switching spool 6, and the diagrams (damping resistance to piston position, piston speed to piston position) indicate the states. The diagram shows the relevant operating characteristics.

(1) Determine the point of inflection of the characteristic in the cushion region of the piston 1 from the surface value of the exhaust valve closing characteristic, and assemble the multi-stage cushion switching spool 6, the sleeve 7, and their cylinder portion 2, and set two positions.

(2) Under the condition of state 1 in Fig. 3, the piston 1 moves the oil in the ac from the hydraulic oil port 4 to the cam drive hydraulic pressure with almost no resistance due to the force of the exhaust valve return (04 in Fig. 1). Return to actuator 3.

(3) Under the condition 2 in Fig. 3, the first stage of the cushion switching spool 60 is connected to the system pump 11 for pilot valve oil supply, the pilot check valve 9 opens, and the cushion volley receives resistance from the throttle valve 8. -The oil in the tank returns to the tank. During this time, piston 1 and exhaust valve (03 in Figure 1)
is reduced to an appropriate amount by adjusting the throttle amount of the throttle valve 8, and has a damping effect.

(4) Under the condition of state 3 in Fig. 3, the second stage of the cup run switching spool 60 is also connected to the system pump 11, and the pilot check valve 13 is opened, so the load resistance is reduced (damping open). The piston 1, which has been decelerated and before stopping, is yl? due to the small external force of the exhaust valve scavenging air. Move to the vicinity of Tom and seat the exhaust valve securely and without shock.

(5) Similarly, by using a multi-stage cushion switching spool and sleeve as a switching mechanism and providing the corresponding number of pilot check valves and variable throttle valves, multi-stage variable damping on a polygonal line and damping release at the final stage can be achieved. .

(6) The conventional method only has the function corresponding to state 2 in Fig. 3.

(,) Damping is too effective and the exhaust valve cannot be completely closed in a timely manner at the seated position, reducing the efficiency of the internal combustion engine. Additionally, the oil column between the cam drive hydraulic actuator may run out, generating negative pressure and causing malfunction.

(b) Due to insufficient damping, the exhaust valve receives a large impact when seated, resulting in damage or shortened service life.

The above-mentioned drawbacks are inherent, and the power and stiffness cannot be achieved through adjustment.

The above case has the following effects.

(1) Ideal exhaust valve characteristics can be realized hydraulically.

(2) Multi-stage damping adjustment not only enables timely and reliable exhaust valve closing operation, but also enables operation that minimizes the impact force applied to the exhaust valve seat.

(3) Free parts from damage and extend lifespan0 (4) Eliminate oil column shortages.

[Brief explanation of the drawing]

FIG. 1(a) is an explanatory diagram showing a conventional piston-type seating damping device for a hydraulically driven exhaust valve. FIG. 1(b) is an explanatory diagram showing the main parts of the seated damping device of the same check valve type, FIG. 2 is an explanatory diagram showing the device of the first embodiment according to the present invention, and FIG. 3 is an explanatory diagram showing the state change of the multistage switching spool. FIG. 3 is an explanatory diagram showing changes in damping resistance and piston speed corresponding to each state. 1... Piston of hydraulic actuator, 4... Hydraulic oil J-), 6... Cushion switching spool. 9113...Pilot check valve, 8.12...
Variable throttle valve. (゛1st sip (0) Fang 1 mon (13) 1 large sugar 1-sized> 1 large dried 2-> λ large 183 (Procedural amendment (voluntary) May 4, 1980 Commissioner of the Patent Office Kazu Wakasugi Husband 1, Indication of the case Patent Application No. 24347 of 1982 2, Name of the invention Exhaust valve seating damping device 3, Person making the amendment Relationship to the case Patent applicant, sub-agent 5, Specification subject to amendment Detailed Description of the Invention and Drawing 6 Contents of the Amendment (1) The phrase "inside the hydraulic cylinder" on page 2, line 5 of the specification is amended to read "inside the hydraulic actuator" (2) The phrase "exhaust valve drive cylinder" from line 7 to line 8 of page 2 is corrected to "exhaust valve drive hydraulic cylinder." (3) The phrase "1 hydraulic cylinder" in line 10 of page 2 is corrected to [
Hydraulic actuator”. (4) On page 4, lines 4 to 5, the phrase "exhaust valve shock" has been corrected to "exhaust valve seating shock." (5) [Refueling port inside the pilum] on page 4, line 16
Correct the text to read "oil supply/drain port inside the volume." (6) In the second line of page 6, the phrase "Returns to the tank." should be corrected as follows: "Returns to the cam-driven hydraulic actuator 3 for suction action through oil supply and drainage l-15." 15. to correct. (8) On page 6, line 8 of the same page, the phrase “returns to the tank from 12” should be replaced with “from 12 the suction action actuator 〇-Y3
Return to ” he corrected. (9) On page 6, line 11, "Detom 16" is corrected to "Detom 15." ◇O From the 14th line to the 15th line on page 6 of the same page, replace the text "Check valve 14 through oil supply 4-to 5" with [Oil supply/drain port 5
The correction is mainly made through the check valve 14j. Q.
Return to actuator 3. ” he corrected. (6) After page 9, line 12, add a new line and add the following sentence. ) Depending on the return oil supply method of the cam drive hydraulic actuator 3, the return oil of the throttle valves 8 and 12 may be directly supplied to the tank 21.
Danging can also be applied by using a hydraulic circuit that returns to normal. ” Figures 2 and 3 of the alpha inspection drawings will be corrected as shown in the attached appendix. 7. List of attached documents (1) Drawings (Figures 2 and 3) 1 sheet each, 2nd entry

Claims (1)

[Claims] In a hydraulic exhaust valve drive device for a diesel engine, a cushion area is formed between the cylinder bottom of a hydraulic actuator of an exhaust valve and a hydraulic oil hoard, and the cushion area is provided in the cushion area and is sequentially actuated by the movement of the piston of the hydraulic actuator. A multi-stage cushion switching spool is provided corresponding to the cushion switching spool, and a pilot check valve is driven by the spool, and a pilot check valve is connected to the pilot check valve to generate a multi-stage polygonal damping resistance in the flow. A seated damping device for an exhaust valve, characterized in that it is equipped with a variable throttle valve that releases damping.