JPH0263084B2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to an exhaust valve drive device for an internal combustion engine.

FIG. 1 shows a conventional exhaust valve hydraulic drive system for a two-stroke internal combustion engine. In the figure, a piston 12 reciprocates inside a cylinder block 11, and an exhaust valve box 15 on the top of which holds an exhaust valve 13 with a bush 14.
has been established. The upper part of the piston 12 is the combustion chamber 10
The exhaust valve box 15 has an exhaust passage 1 from the exhaust valve 13.
There are 9. A hydraulic piston 18 that slides within a valve spring 16 and a hydraulic cylinder 17 is attached to the exhaust valve 13 . Hydraulic cylinder 17 is high pressure pipe 2
High-pressure hydraulic oil is supplied from a hydraulic pump 22 via 1. Here, the roller 33 is driven by the cam 32 attached to the camshaft 31, and the plunger 23 of the hydraulic pump 22 is further driven. A spring 34 is provided on the roller 33. As shown in FIG. 1, the exhaust valve 13 is closed by a valve spring 16, and the roller 33 is closed by a spring 34,
It is being pushed to 2. Here, when the camshaft 31 rotates and the cam 32 pushes up the roller 33, the plunger 23 rises and compresses the hydraulic oil in the hydraulic pump 22. Therefore, the pressure of the hydraulic oil in the hydraulic cylinder 17 increases via the high pressure pipe 21,
A force that opens the exhaust valve 13 downward acts on the hydraulic piston 18 . Changes in the pressure P of the hydraulic oil in the hydraulic cylinder 17 and the lift L of the exhaust valve 13 at this time are shown in FIG. 2 with the crank angle as the horizontal axis. As the plunger 23 rises, P rises and the valve spring 16
The pressure becomes P ₁ which balances the setting force of . The plunger 23 further rises, and the pressure of the hydraulic oil balances the pressure of the working gas in the combustion chamber 10 at a crank angle θ ₁ .
At _P2 , the exhaust valve 13 begins to open. When the exhaust valve 13 continues to open, the working gas in the combustion chamber 10 flows out into the exhaust passage 19, so the working gas pressure in the combustion chamber 10 decreases, the working gas pressure in the exhaust passage 19 increases, and both Since the difference between the two becomes smaller, the hydraulic oil pressure also decreases, and when the two working gas pressures become equal at θ ₂ , the only thing left to do is to open the exhaust valve 13 with the hydraulic oil pressure corresponding to compressing the valve spring 16. I'm going to go. When the camshaft 31 further rotates and the plunger 23 begins to descend, the hydraulic cylinder 17
The pressure of the hydraulic oil inside begins to decrease, and the exhaust valve 13 begins to close due to the force of the valve spring 16. Hydraulic oil pressure P
The exhaust valve 13 finishes closing at the crank angle θ ₃ at which the pressure returns to the pressure P ₁ that balances the setting force of the valve spring 16.

However, the above method has the following drawbacks.

In FIG. 2, the pressure of the hydraulic oil corresponding to the force of the valve spring 16 is shown by a dashed line. The shaded area in FIG. 2 is the work of the plunger 23 required to drive the exhaust valve 13 against the pressure difference between the working gas in the combustion chamber 10 and the exhaust passage 19 that act on the exhaust valve 13. That is, in the conventional exhaust valve hydraulic drive system, the camshaft must perform this amount of work, which worsens the fuel consumption rate of the engine.

Next, it is necessary to generate a hydraulic oil pressure P ₂ in the plunger 23 that balances the working gas pressure in the combustion chamber 10 shown in FIG.
1 and cam 32. Furthermore, since the cam 32 is fixed to the camshaft 31, it is impossible to change the phase of the cam and the opening/closing timing of the exhaust valve 13 while the engine is operating.

The purpose of the present invention is to eliminate the camshaft and cam device, simplify the structure, reduce the power consumption of the hydraulic drive device, and provide an exhaust system in which the opening and closing timing of the exhaust valve can be changed during operation by electronic control. The purpose of the present invention is to provide a valve drive device, and its features include an outward-opening exhaust valve that opens toward the outside of the combustion chamber, and a hydraulic piston fixed to the end of the valve stem of the exhaust valve. An inserted fluid pressure cylinder, a solenoid valve installed in the supply path and discharge path of high pressure fluid to the fluid pressure cylinder to control the opening and closing of each path, and a solenoid valve that is driven by the gas pressure in the cylinder to control the generated fluid pressure above It is equipped with a plunger pump that transmits fluid to the cylinder.

The present invention is applicable to internal combustion engines and reciprocating compressors.

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

FIG. 3 is an explanatory diagram showing an exhaust valve driving device according to one embodiment of the present invention.

In the figure, the exhaust valve 40 is of an outward-opening type that opens when raised upward, and a pressure receiving collar 41, that is, a piston is attached to the upper part of the valve stem of the exhaust valve 40. Pressure collar 4
The lower part of the pressure receiving collar 41 is an open oil chamber 42 into which hydraulic oil from the high-pressure oil supply pipe 51 flows through the solenoid valve 71, and the upper part of the pressure receiving collar 41 receives the hydraulic oil from the high-pressure oil supply pipe 51 through the solenoid valve 73 and the check valve 75. This is the closed valve oil chamber 43 into which the oil flows. That is, a fluid pressure cylinder in which the pressure receiving collar 41 slides is formed in the open valve oil chamber 42 and the valve closed oil chamber 43.

Hydraulic oil is stored in the hydraulic oil tank 53,
High-pressure hydraulic oil is supplied to a pressure accumulator 55 by a hydraulic pump 54 driven by a motor or engine crankshaft.

High-pressure hydraulic oil from the pressure accumulator 55 is supplied to the high-pressure oil supply pipe 51
flows into. Return hydraulic oil from the open valve oil chamber 42 and the closed valve oil chamber 43 passes through electromagnetic valves 72 and 74, respectively, is collected in a return pipe 52, and reaches a hydraulic oil tank 53. The solenoid valves 71, 72, 73, and 74 are opened and closed by electric signals from the controller 61, and the controller 61 receives an engine crank angle signal 62.
is input.

Further, the cylinder block 11 is provided with a barrel 82 on which a gas piston 81, on which the working gas in the cylinder acts, slides. At the tip of the gas piston 81 is a hydraulic barrel 83 having a smaller diameter than the gas piston 81.
A hydraulic plunger 84 that slides inside is attached.

The gas piston 81, barrel 82, hydraulic barrel 83, and hydraulic plunger 84 constitute a plunger pump. Hydraulic pressure within hydraulic barrel 83 is coupled downstream of check valve 75 through conduit 85 .

Here, the working gas pressure receiving area in the combustion chamber 10 of the exhaust valve 40 is A _VG , and the pressure receiving collar 41 of the valve opening oil chamber 43 is
The pressure receiving area is A _VO , the pressure receiving area of the gas piston 81 is A _PG , and the pressure receiving area of the hydraulic plunger 84 is
A _PO .

At this time, so that A _VG /A _VO <A _PG /A _PO ,
Determine the dimensions of each.

The operation in the case of the above configuration will be described.

As shown in FIG. 3, when the exhaust valve 40 is closed, the output signal from the controller 61 causes the solenoid valve 74 to close, the solenoid valve 73 to open, and high-pressure hydraulic oil is passed through the check valve 75 into the closed oil chamber 43. acts to close the exhaust valve 40.

If we examine the change in the cylinder internal pressure P _Z with respect to the engine crank angle θ, we will see the results shown in FIG. 4.

When the exhaust valve 40 closes at the crank angle θ ₄ , the working gas in the cylinder begins to be compressed by the piston 12 and the pressure P _Z begins to increase. piston 12
Since fuel is injected into the working gas in the combustion chamber 10 and combusted near the top dead center TDC, P _Z is the maximum pressure P _nax
becomes. Thereafter, P _Z decreases as the piston 12 descends. At crank angle θ ₅ , the exhaust valve 40 begins to open, and P _Z further decreases.

FIG. 4 also shows the lift L of the exhaust valve 40. Here, when the exhaust valve 40 closes at the crank angle θ ₄ , since P _Z is low immediately after closing, the gas piston 81 is operated by the force of the high pressure hydraulic oil acting on the hydraulic plunger 84 through the check valve 75. pressed to the side.

As the crank angle θ further advances and P _Z begins to rise further, the working gas pressure also acts on the gas piston 81, so the oil pressure in the hydraulic barrel 83 exceeds the pressure in the high pressure oil supply pipe 51 and reaches the next (1 ) is the value of the expression.

P _O =A _PG /A _PO ×P _Z (1) This oil pressure acts on the valve-closing oil chamber 43 through the conduit 85. At this time, since the check valve 75 is provided, this oil pressure does not act on the high pressure oil supply pipe 51.

Incidentally, since the working gas pressure also acts on the exhaust valve 40, the force of equation (2) acts upward.

F _U = A _VG × P _Z (2) However, the force that the pressure receiving collar 41 receives downward due to the oil pressure in the valve closing oil chamber 43 is expressed by equation (3).

F _D = A _VO ×P _O …(3) Here, by substituting formula (1), F _D = A _VO ×A _PG /A _PO・P _Z …(4) From formulas (2) and (4), F _U /F _D = A _VG /A _VO・1/(A _PG /A _PO ) ...(5) By the way, as mentioned in the explanation of the structure, it is made so that A _VG /A _VO < A _PG /A _PO , Equation (5) becomes F _U /F _D <1...(6). That is, the downward force F _D becomes larger.

When the crank angle θ ₅ is reached, the output signal from the controller 61 opens the solenoid valve 74 and closes the solenoid valve 73, so that the pressure in the valve-closing oil chamber 43 decreases. Therefore, the exhaust valve 40 begins to open due to the force acting on the exhaust valve 40 due to the cylinder internal pressure _PZ . At this time, the solenoid valve 72 is simultaneously closed by the output signal of the controller 61, the solenoid valve 71 is opened, and high-pressure hydraulic oil acts on the valve-opening oil chamber 42. As a result, the exhaust valve 40 is reliably opened.

Furthermore, the crank angle θ is the bottom dead center of the piston 11.
After passing BDC, the output signal from the controller 61 causes the oil pressure in the valve opening oil chamber 42 to decrease, and the oil pressure in the valve closing oil chamber 4 to decrease.
The hydraulic pressure at No. 3 increases and the valve begins to close, and the valve closes at crank angle θ ₆ .

The above case has the following effects.

As shown in FIG. 3, since a large camshaft and cam are not required, the structure is simple and the cost can be significantly reduced.

Furthermore, since the opening and closing timing of the exhaust valve 40 is determined by the output signal of the controller 61, when the engine speed becomes low, the opening and closing timing of the exhaust valve 40 is delayed and the effective stroke of the piston is increased to reduce fuel consumption. The opening/closing timing of the exhaust valve 40 can be changed depending on the operating state of the exhaust valve 40.

In addition, an outward-opening type exhaust valve 40 is used,
It is necessary to prevent the exhaust valve 40 from opening due to the high cylinder internal pressure P _Z that acts during the valve closing, especially P _nax shown in FIG. 4, but as shown in equation (6),
Regardless of the value of P _nax , the force pressing down on the exhaust valve 40 becomes large and does not open.

Further, the gas piston 81 moves to generate high oil pressure when P _Z is high, but returns to the working gas side as P _Z decreases, so no energy loss occurs.

Furthermore, when the valve is opened, the cylinder pressure P _Z acts in a direction that accelerates the valve opening, so the oil pressure in the valve opening oil chamber 42 is low, and when the valve is closed, the cylinder pressure acting on the exhaust valve 40 and the exhaust passage 19 are Since the working gas pressure is the same, the oil pressure in the valve-closing oil chamber 43 may be low.

As a result of the above, the pressure in the pressure accumulator 55 may be low as a whole, the power consumption of the hydraulic pump 54 is reduced, and the fuel efficiency of the engine as a whole can be improved.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram showing a conventional exhaust valve hydraulic drive device, Fig. 2 is a diagram showing changes in the lift L of the exhaust valve of the device shown in Fig. 1 and the pressure P of the hydraulic oil in the hydraulic cylinder, and Fig. 3 The figure is an explanatory diagram showing an exhaust valve driving device according to one embodiment of the present invention, and FIG. 4 is a diagram showing changes in cylinder internal pressure and lift of the exhaust valve of the device in FIG. 3. 10... Combustion chamber, 40... Exhaust valve, 41... Pressure receiving collar, 42... Valve open oil chamber, 43... Valve closed oil chamber, 71, 72, 73, 74... Solenoid valve, 81...
...Gas piston, 82...Barrel, 83...Hydraulic barrel, 84...Hydraulic plunger.

Claims (1)

[Claims] 1 Exhaust valve formed to open outward toward the outside of the combustion chamber, a fluid pressure cylinder in which a piston fixed to the end of the valve stem of the exhaust valve is inserted, and supply of high pressure fluid to the fluid pressure cylinder An internal combustion engine, characterized in that it is equipped with a solenoid valve that is provided in each of the passages and a discharge passage and controls the opening and closing of the passages, and a plunger pump that is driven by gas pressure in the cylinder and transmits the generated fluid pressure to the fluid pressure cylinder. Exhaust valve drive device.