JPS61229911A - Fluid pressure drive type tappet valve controller - Google Patents

Abstract

PURPOSE:To achieve a reliably functionable valve mechanism by feeding pressure oil to a hydraulic mechanism provided at the upper end section of an intake and exhaust valve to open the valve while compressing a pneumatic piston through open- valve function and closing the valve with previous compression air when discharging oil from the hydraulic mechanism. CONSTITUTION:The upper end of the stem of an intake and exhaust valve 1 is fitted in the cylinder 7 while a hydraulic path changeover sleeve 62 is provided in the inner face of cylinder. The working oil is fed from a tank 10 through a pump 12, an accumulator 13 and a changeover valve 15 to the working oil supply system 9 or the oil path 14 to the tank while a portion of the oil path from the accumulator 13 will switch between the upper or the lower end of sleeve 62 and the oil discharge path 7- through a reducing valve 60 and a changeover valve 61. The changeover valves 15, 61 are functioned through a controller 16 while matching with specific engine timing to feed the pressure oil to the working oil supply system 9. When the hole in sleeve 62 will communicate with the interior of cylinder, the valve 1 is opened to compress the air in the chamber 5 by means of a pneumatic piston 4 while when closing the valve,the pneumatic pressure is used for discharging the pressure oil and for closing the valve.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a fluid pressure-driven valve control system for controlling the opening and closing of an intake valve or an exhaust valve of an internal combustion engine using fluid pressure.

Conventional technology In order to improve the performance of internal combustion engines, the conventional valve control mechanism of cam, tappet, and rocker arm system was replaced with the control mechanism of the intake valve or exhaust valve using Japanese Patent Laid-Open No. 53-13901.
A valve train I1 driven by fluid pressure as shown in Publication No. 1
1 control mechanism has been proposed in the past. According to this, the intake valve or the operating characteristics of the intake valve can be arbitrarily adjusted to 1ilII.
It is particularly convenient for controlling the timing of opening and closing to increase the effective work of the engine.

FIG. 7 shows such a conventional fluid pressure driven valve control device, in which 41 is an exhaust valve (41) provided on a cylinder cover 42.
intake valve). A piston 44 that slides within a hydraulic cylinder 43 is formed at the tip of the valve stem of this exhaust valve 41.
A return spring 45 biases the exhaust valve 41 to close. 4
6 is an oil tank to which a supply pipe 49 equipped with a hydraulic pump 47 and a pressure accumulator 48 is connected. 50 is a discharge pipe. Both of these conduits 49 and 50 are connected to the hydraulic cylinder 43 via an IIi control valve 51 constituted by a throttle valve. 52 is MIll valve operation HW1, IIJw section 5
3 and an actuator 54.

On the other hand, 55 is a position detector for the exhaust valve 41, which outputs a position detection signal to the control section 53.

In such a configuration, the speed of the valve 41, that is, the speed of the piston 44, must be adjusted appropriately to prevent overshoot of the valve 41 when the valve is opened and vibration and noise due to seating when the valve is closed. For this purpose, it is necessary to reduce the speed of the piston 44 from the latter half of its stroke and to minimize the inertial force of the exhaust valve 41 when it is fully open and when it is fully open (seated). Conventionally, this has been dealt with by detecting the position of the valve 41 with the position detector 55 and adjusting the amount of restriction of the control valve 51, that is, the flow rate of the oil, with the operating device 52.

Problems to be Solved by the Invention However, in such a conventional device, (1) the control valve operating device ff52 has a complicated structure and is expensive.

■ A position detector 55 for the exhaust valve 41 is required.

(2) The control valve 51 for controlling the speed of the exhaust valve 41 is for a large flow rate and needs to be expensive.

There is a problem.

Furthermore, in recent years, there has been a trend to increase the effective work of engines in order to improve their performance, and it has become necessary to increase the speed of the exhaust valve 41, that is, the piston 44, due to the characteristics of gas flow. This means that the flow rate of oil supplied to the hydraulic cylinder 43 is increased, and the time required for the stroke of the piston 44 is shortened. That is, in the current 180 rpm engine, the time is about 3 O-sec, but if the speed of the piston 44 is doubled, it becomes about 151 sec.
It becomes C. In the conventional apparatus described above, the control valve 51 must be operated within such an extremely short period of time to control the supply oil flow rate, and there is a problem in that it is difficult to realize this.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to obtain a fluid pressure-driven valve operating IIIwJ device that has a simple configuration, operates reliably, and is capable of high-speed control.

Means for Solving the Problems In order to achieve the above object, the fluid pressure-driven valve train control according to the present invention has a rod-shaped piston interlocked with an intake valve or an exhaust valve, which is installed above the combustion chamber of the engine. slidably inserted into a fluid pressure cylinder, forming an axial fluid passage in the rod-shaped piston from an end surface of the rod-shaped piston toward the inside thereof;
A supply and discharge hole is formed extending from a side surface of the rod-shaped piston toward the fluid passage, and a communication port that communicates with the supply and discharge hole is formed in a side wall of the fluid pressure cylinder, and the rod-shaped piston and the fluid pressure cylinder are connected to each other. A cylindrical sub-piston that can reciprocate between a first position and a second position along the sliding direction of the rod-shaped piston is fitted between the sub-piston and the sub-piston. is in the first position, the supply and discharge hole communicates with the communication port when the intake valve or exhaust valve is in the seated state, and the supply and discharge hole is in communication with the communication port when the intake valve or exhaust valve is in the maximum valve lift state. When the hole and the communication port are cut off and the sub-piston is in the second position, the supply/discharge hole in the maximum valve lift state communicates with the communication port, and the supply/discharge hole in the seated state communicates with the sub-piston. A communication passage is formed to cut off the communication port, and by the sliding of a rod-shaped piston within the fluid pressure cylinder as the intake valve or exhaust valve opens and closes, In order to gradually narrow down the flow path, the cross section of the supply/discharge hole and the communicating path is tapered in the axial direction at necessary locations.

Therefore, since a working fluid flow path is formed between the side of the fluid pressure cylinder and the side of the rod-shaped piston that is slidably fitted into the fluid pressure cylinder, the stroke of the intake valve or exhaust valve, that is, the fluid pressure The flow rate to the cylinder is controlled only by the axial dimensions of the supply and discharge holes, etc., so there is no need for a conventional complicated control valve operating device, and the control valve is a directional valve. Since it can be configured easily and does not require flow rate control, it can provide high-speed response and can be made at low cost. In addition, because the cross section of the necessary parts of the supply/discharge hole etc. is tapered in the axial direction, the flow velocity of the working fluid, that is, the speed of these valves, can be reduced before the maximum lift of the intake or exhaust valves and before they are seated. , it is possible to reliably prevent overshoot, vibration and noise when seating.

EXAMPLE An example of the present invention will be described below. In FIG. 1, reference numeral 1 denotes an exhaust valve (intake valve) provided on the cylinder cover 2, and the tip of the valve stem of the exhaust valve 1 slides in an air cylinder 3 provided on the top surface of the cylinder cover 2. An air compression piston 4 is integrally formed. 5 is an air chamber, and 6 is an air supply path to the air chamber 5. air cylinder 3
A hydraulic cylinder 7 as a fluid pressure cylinder is integrally formed in the upper part of the hydraulic cylinder 7, while a rod-shaped piston 8 which is slidably fitted into the hydraulic cylinder 7 is integrally formed with the air compression piston 4. A cylindrical sub-piston 62 is fitted between the rod-shaped piston 8 and the hydraulic cylinder 7. 9
1 is a hydraulic oil supply system to the hydraulic cylinder 7, 10 is an oil tank, 11 is a supply pipe line equipped with a hydraulic pump 12 and a pressure accumulator 13, and 14 is a discharge pipe line. Further, 15 is an illm valve constituted by a switching valve, and 16 is a control device thereof.

Further, 69 is a first connecting pipe branched from the supply pipe line 11 and connected to the hydraulic cylinder 7, and 7o is a second connecting pipe branched from the discharge pipe line 14 and connected to the hydraulic cylinder 7. It is. A switching valve 61 operated by the υ control device 16 is provided in the middle of both the connecting pipes 69 and 70, and a switch valve 61 is provided in the middle of the connecting pipe 69 to connect the switching valve 61 and the supply pipe 11 at the hook. A pressure reducing valve 60 is provided.

Next, the hydraulic cylinder 7 and its surroundings will be explained in detail based on FIG. 2. Figures a and e show the state when the exhaust valve 1 is seated, figures c and c show the state when the exhaust valve 1 reaches its maximum lift, and figure d shows the state just before it is seated. It shows. As shown, the rod-shaped piston 8 has an axial fluid passage 1 extending from its end surface 17 toward its interior.
8 is formed and the side surface 19 of the fluid passage 1 is formed.
A radial supply/discharge hole 2o penetrating toward 8 is formed. 22 is a clearance chamber between the rod-shaped piston 8 and the hydraulic cylinder. Between the supply and discharge hole 20 of the rod-shaped piston 8 and the end face 17, there is a small-diameter soft-wearing and waste discharge hole 2.
3 is similarly penetrated. 29 is a soft clothing waste discharge hole 23
This is an annular structure formed on the outer periphery of the rod-shaped piston 8 in accordance with the above.

The sub-piston 62 has an annular groove 64 on its inner surface that can always communicate with the supply/discharge hole 2o even when the rod-shaped piston 8 rotates around its axis. Communication passages 63 are formed at several locations around the annular @ 64 to communicate the supply/discharge hole 20 of the rod-shaped piston 8 and the communication port 24 of the hydraulic cylinder 7 . The sub-piston 62 can reciprocate between a first position (a, b in Fig. 2) and a second position (c, d, e in Fig. 2) along the sliding direction of the rod-shaped piston 8. Both ends in the axial direction are formed stepwise to form hydraulic chambers 65 and 66 between the hydraulic cylinder 7 and the hydraulic cylinder 7. In addition, Fig. 2 f
shows a partially cutaway overall perspective view of the sub-piston 62.

An annular groove 26 is formed on the inner surface of the hydraulic cylinder 7 in correspondence with the communication port 24, so that even when the sub-piston 62 rotates around the axis, the communication port 24 and the communication path 63, that is, the supply and discharge hole 20, are connected. communication is possible at all times. 28 is a differential oil discharge port for the soft seat, which serves as a fluid discharge port for the soft seat;
It is formed to have a small diameter to match the soft clothing waste discharge hole 23.

Note that the upper end of the sub-piston 62 is located at the soft-fitting waste discharge hole 2.
3 and the soft seating hydraulic oil outlet 28 (Fig. 2 c, d)
, e) or shut off (Fig. 2 a, b). Reference numerals 67 and 68 denote fluid supply and discharge ports for driving the sub-piston 62, which are formed to match the hydraulic chambers 65 and 66, and are connected to connection pipes 69 and 70, respectively.

Next, the positional relationship of each part will be explained with reference to FIG. 2g. In the seated state of the second FRa, the upper edge of the annular groove 64 of the sub-piston 62 and the lower edge of the supply/discharge hole 20 are separated by a distance A from each other. Further, the soft agricultural hydraulic oil discharge port 28 and the discharge hole 23 are blocked by the upper end portion of the sub-piston 62. In the state of maximum lift shown in FIG. 2, the lower edge of the annular groove 64 corresponding to the communication path 63 and the upper edge of the supply/discharge hole 20 are aligned, and the two are blocked. When the sub-piston 62 is displaced in this state, the annular groove 62 is displaced as shown in FIG. 2g.
4 and the supply/discharge hole 2G communicate with each other again. In the state just before seating shown in FIG. 2g, the upper edge of the annular groove 64 and the supply/discharge hole 2
0 coincides with the lower edge of the soft-wearing agricultural oil discharge hole 23 and the soft-wearing agricultural hydraulic oil outlet 28 to communicate with each other. In the seated state shown in FIG. 2g, the upper edge of the annular groove 64 and the lower edge of the supply/discharge hole 20 are offset by a distance B from each other.

The operation of the above configuration will be explained below. First, in the exhaust valve opening stroke, in the state shown in Fig. 2g, the υ control valve 1 is
Supply pipe 1 connecting 5 to the hydraulic pump 12 from the neutral position
Switch to 1. Then, the high-pressure hydraulic oil reaches the communication port 24, passes through the passage 63 of the sub-piston 62, and enters the supply and discharge hole 2.
0 into the clearance chamber 22 via the fluid passage 18. Then, the hydraulic pressure in the clearance chamber 22 is increased by the load 11Fax due to the exhaust pressure Pex from the load FZ due to the gas pressure P2 in the *m combustion chamber shown in Fig. 1 and the load 1''a due to the pressure Pa in the air chamber 5. When the force becomes larger than the pulled load, the rod-shaped piston 8 begins to descend.

That is, using the pressure receiving area AON oil pressure P of the rod-shaped piston 8, P > (F Z + F a - F e
)/A.

At this time, the rod-shaped piston 8 starts to descend and reaches the second position in terms of RH.
The maximum lift point shown in the figure is reached.

FIG. 3 shows the lift of the exhaust valve 1, that is, the stroke of the rod-shaped piston 8, the speed of the exhaust valve 1, that is, the speed of the rod-shaped piston 8, and the hydraulic oil flow rate that determines the speed for the valve opening stroke and the valve closing stroke. This is what is shown. Here, the speed of the rod-shaped screw, ton 8, is drawn in accordance with the outline of the speed change pattern realized in a conventional cam-driven valve train.

FIG. 4 shows the change in the opening area between the supply/discharge hole 2G and the annular portion 11364 of the sub-piston 62 when the rod-shaped piston 8 is lowered, together with the lift of the exhaust valve 1 and the speed of the rod-shaped piston 8. be.

Here, since the cross-sectional shape of the supply/discharge hole 20 is circular, this cross-sectional shape becomes tapered in the axial direction, and the opening area, that is, the flow path of the hydraulic oil, is gradually narrowed before the exhaust valve 1 reaches its maximum lift. It turns out. As a result, the rod-shaped piston 8 is reliably decelerated from the latter half of the stroke, and therefore the rod-shaped piston 8 is
It is no longer necessary to perform speed control, and an inexpensive switching type control valve 15 is sufficient, and high-speed response is possible.

In FIG. 4, at the position W1 shown in ■ (FIG. 2 b), the opening area becomes O, and the supply of hydraulic oil is stopped, but the exhaust valve 1
Because of the inertial force of the exhaust valve 1 and the leakage of hydraulic oil, the exhaust valve 1 advances a short distance from that shown in FIG. 2 and then stops.

This corresponds to the position shown in Figure 4, where exhaust valve 1
is set to be fully open. When the exhaust valve 1 is fully opened, the load due to the gas pressure in the combustion chamber is small, so the hydraulic pressure due to the hydraulic oil and the load Fa in the air chamber 5 are reduced.
It is thought that they are almost balanced.

This makes it possible to omit an overshoot prevention mechanism, stopper, and the like. Note that after the communication between the supply and discharge hole 20 and the annular valve 64 is cut off, the II control valve 5 is returned to the neutral position at an appropriate time to cut off the supply of hydraulic oil to the hydraulic cylinder 71 body. Thereafter, the switching valve 61 is switched, the sub-piston 62 is moved up and down as shown in FIG. At this time, since only sealing oil exists in the communication port 24, the rod-shaped piston 8 is not displaced. In addition, since the sub-piston 62 can be easily driven using only low-pressure hydraulic pressure,
The pressure of the hydraulic oil from the supply pipe 11 is reduced by the pressure reducing valve 60 and used. Note that if hydraulic oil is supplied from a separately driven low-pressure pump, the power can be reduced by 8!1$1.

In the exhaust valve closing stroke, the control valve 15 is connected to the exhaust pipe line 14 from a neutral state. As a result, the pressure in the system decreases, and the hydraulic oil that was pressing against the rod-shaped piston 8 in the hydraulic cylinder 7 is discharged through the supply and discharge hole 2o through the communication passage 63 and the communication port 24 of the sub-piston 62. As a result, the hydraulic pressure decreases, and the rod-shaped piston 8 is displaced by the air load Fa in the air chamber 5. The relationship between the piston speed and the discharged oil flow rate at this time is also shown in FIG.

FIG. 5 shows the supply/discharge hole 2o and the sub-piston 6 at this time.
The change in the opening area between the second annular groove 64 and the second annular groove 64 is shown in the same manner as in FIG. Also here, the cross-sectional shape of the supply/discharge hole 20 is circular. In the latter half of the valve closing stroke, especially after the position shown in ■ where the opening area is minute, the rod-shaped piston 8
The speed decreases rapidly, and at the position (corresponding to Figure 2 d) shown in (2), the opening area becomes 0, and there is no discharge of hydraulic oil.

However, the rod-shaped piston 8 is further displaced by the inertia force of the exhaust valve 1, and after this, the sub-piston 62 first releases the interruption between the soft-fitting and waste hydraulic oil outlet 28 and the soft-seating drain hole 23. Therefore, the soft seating waste hydraulic oil discharge port 28 and the soft seating discharge hole 23 communicate with each other. As a result, the open area of the discharge port 28 and the discharge hole 23 gradually increases, and the damper's l.
It will fulfill its function. For this reason, the exhaust valve 1 is
The speed gradually decreases over a distance of 8 to achieve soft seating, and the robot is completely seated at the position indicated by V in FIG.

In the above description, the supply/discharge hole 20 has a circular cross-sectional shape, but for example, as shown in FIG. 6a.

It may be as shown in b.

Further, in the above, the cross-sectional shape of the supply/discharge hole 20 is tapered, but the cross-sectional shape of the communication passage 63 of the sub-piston 62 may be tapered. In this case, the annular groove 64 is formed on the rod-shaped piston 8 side. There is a need to.

Effects of the Invention As described above, according to the present invention, there is no need for the conventional multi-feed, four-control valve operation 1111, and the υ control valve can be configured with a directional switching valve, so flow mi control is not required. It is possible to achieve high-speed response from the valve and to make it inexpensive, and since the cross section of the necessary mtm part of the supply/discharge hole etc. is formed into a tapered shape in the axial direction, The flow velocity of the working fluid, ie, the velocity of the valve, can be reduced at the front, and overshoot, vibration and noise during seating can be reliably prevented.

[Brief explanation of the drawing]

Fig. 1 is a system diagram of one embodiment of the present invention, the second factor is a diagram of details around the hydraulic cylinder and operation procedure, Fig. 3 is a factor showing the relationship between valve lift, piston speed, and hydraulic oil flow rate, and the fourth factor is a diagram showing the relationship between valve lift, piston speed, and hydraulic oil flow rate. Figure 5 shows the change in opening area when the valve is open, Figure 5 shows the change in opening area when the valve is closed, Figure 6 shows another example of the shape of the supply/discharge hole, and Figure 7 shows the change in opening area when the valve is closed. It is a system diagram of a conventional example. 1... Exhaust valve (intake valve), 3... Air cylinder, 4
... Air compression piston, 7 ... Hydraulic cylinder (fluid pressure cylinder), 8 ... Rod-shaped piston, 18 ... Fluid passage, 20 ... Supply and discharge hole, 23 ... Soft seating discharge hole , 24... Communication port, 28... Soft seating hydraulic oil outlet (soft seating pressure fluid outlet), 62... Sub piston,
83...Communication path, 64...Annular groove agent Yoshihiro Morimoto Fig. 1 4--Female 1 pressure, Shima piston 7- Extraction pressure 9yy" (A4 main pressure silant) I--
(K piston Fig. 3)

Claims (1)

[Scope of Claims] 1. In a fluid pressure-driven valve control device that uses fluid pressure to control the opening and closing of an intake valve or exhaust valve of an internal combustion engine, a rod-shaped piston that interlocks with the intake valve or exhaust valve is connected to the engine. It is slidably inserted into a fluid pressure cylinder provided above the combustion chamber, and forms an axial fluid passage in the rod-shaped piston from the end surface of the rod-shaped piston toward the inside thereof, and from the side surface of the rod-shaped piston. A supply and discharge hole penetrating toward the fluid passage is formed, a communication port communicating with the supply and discharge hole is formed in a side wall of the fluid pressure cylinder, and a rod-shaped piston is disposed between the rod-shaped piston and the fluid pressure cylinder. a first position along the sliding direction and a second position along the sliding direction of the
A cylindrical sub-piston that can be slid back and forth between the sub-piston and the first position is fitted into the sub-piston, and when the sub-piston is in the first position, the intake valve or the exhaust valve is seated. communicating the supply/discharge hole and the communication port, and blocking the supply/discharge hole and the communication port when the intake valve or the exhaust valve is in a maximum valve lift state;
and when the sub-piston is in the second position, a communication passage is provided that allows communication between the supply and discharge hole in the maximum valve lift state and the communication port, and blocks off the supply and discharge hole and the communication port in the seated state. The flow path can be gradually narrowed before the maximum lift of the intake valve or exhaust valve and before the seating of the intake valve or exhaust valve by sliding a rod-shaped piston within the fluid pressure cylinder as the intake valve or exhaust valve opens and closes. A fluid pressure-driven valve control device characterized in that a cross section of a necessary portion of the supply/discharge hole and the communication passage is tapered in the axial direction. 2. The rod-shaped piston is characterized by having a soft seating discharge hole that communicates the soft seating fluid discharge port formed in the fluid pressure cylinder immediately before the intake valve or the exhaust valve is seated with the fluid passage in the axial direction. A fluid pressure driven valve train control device according to claim 1.