JP4831839B2 - Engine valve actuator and internal combustion engine - Google Patents

Description

  The present invention relates to an engine valve actuator and an internal combustion engine for driving an intake valve and an exhaust valve of an internal combustion engine at high speed and accurately.

Conventionally, in order to increase the degree of freedom of control of an internal combustion engine, a hydraulic valve drive device that controls an intake valve and an exhaust valve using an actuator, a hydraulic servo valve, and the like has been used.
For example, there has been proposed a hydraulic valve driving device that performs only a valve opening operation (lift) with an actuator (for example, Patent Documents 1 and 2).
There has also been proposed a hydraulic valve drive device that opens (lifts) and closes a valve with an actuator (for example, Patent Document 3).

In the hydraulic valve drive device that controls the intake and exhaust valves using the hydraulic servo valves disclosed in each of the above patent documents, the position of the piston of the actuator is detected by a displacement meter in order to increase control accuracy. However, it is necessary to perform feedback control based on the detected value.
However, Patent Documents 1 to 3 do not describe anything about the displacement meter.
And in what was disclosed by patent document 1, there exists a problem that it is difficult to provide a displacement meter.

In the double rod type disclosed in Patent Documents 2 and 3, it is possible to provide a displacement meter on the piston rod that protrudes on the opposite side of the intake valve and the exhaust valve.
However, the double rod type has a problem that the dimensions (particularly the length) of the entire actuator including the displacement meter increase.
Furthermore, oil is not allowed to leak to the opposite side (outside) of the intake valve and exhaust valve (although slight leakage of hydraulic oil to the intake valve and exhaust valve side is allowed), Due to the structure, there is a problem that the piston rod on the side opposite to the intake valve and the exhaust valve cannot be completely sealed.

  Moreover, in the thing of patent document 3, although opening operation | movement (lift) and closing operation | movement consume hydraulic energy, there exists a problem that energy efficiency is bad.

JP 2003-328713 A JP 2007-231912 A JP 2005-139994 A

  The present invention has good hydraulic energy efficiency at the time of opening (lift) and closing by an actuator, high control accuracy of the intake valve and exhaust valve, hydraulic oil does not leak to the outside, and a displacement meter An engine valve actuator and an internal combustion engine are provided.

  The present invention has been made to solve the above-described conventional problems, and each invention described in the claims employs each means described below as an engine valve actuator.

(1) The engine valve actuator of the first means is
In an engine valve actuator that drives an engine valve of an internal combustion engine,
A valve drive cylinder having a rod through hole drilled on the engine valve side;
A valve rod inserted through the rod through hole;
A valve drive piston attached to one end of the valve rod;
A three-way switching control valve mounted adjacent to the side of the valve drive cylinder;
A valve opening hydraulic passage connecting the valve drive cylinder upper chamber on the upper surface side of the valve drive piston and the three-way switching control valve;
A hydraulic supply passage for supplying hydraulic oil from a hydraulic pump to the three-way switching control valve;
The valve drive cylinder lower chamber on the lower surface side of the valve drive piston is connected to the hydraulic pressure supply passage.

(2) The second means is the engine valve actuator of the first means,
A piston central recess formed in the center of the upper surface of the valve drive piston;
A target attached to an inner surface of the piston central recess;
A displacement meter inserted from the upper lid of the valve drive cylinder so as to face the target is provided.

(3) The third means is the engine valve actuator of the first or second means,
The three-way switching control valve is
A spool that slides within a sleeve secured within the manifold block;
The hole for controlling the amount of hydraulic oil to the spool hole communication chamber 51 formed on the outer peripheral surface of the spool is formed such that the circumferential width on the front end side is smaller than the circumferential width on the rear end side. Features.

(4) The internal combustion engine of the fourth means is
A cylinder block;
A combustion piston that moves up and down in the cylinder block;
An exhaust valve and an intake valve;
The engine valve actuator according to any one of the first to third means for driving the exhaust valve and the air supply valve, respectively.

The invention according to each claim described in the claims employs each of the above-described means, and can reduce the energy supplied from the hydraulic pump and recover a part of the energy when pressed.
In addition, since the displacement meter is housed in the valve drive cylinder, there is no need to protrude the rod on the side opposite to the exhaust valve and the supply valve side, and the overall valve drive device is compared to the conventional double rod cylinder type. The dimensions can be reduced and a sliding seal is not required.

It is a schematic diagram of the engine valve actuator concerning a 1st embodiment of the present invention. It is a detailed schematic diagram of the single rod cylinder in FIG. FIG. 3 is a longitudinal end view of a three-way switching control valve in FIG. 2 and a plan view of a sleeve. It is AA sectional drawing of FIG. It is BB sectional drawing of FIG.

Hereinafter, an engine valve actuator according to an embodiment of the present invention will be described with reference to FIGS. 1 and 2.
FIG. 1 is a schematic diagram of an engine valve actuator according to a first embodiment of the present invention, and FIG. 2 is a detailed schematic diagram of a single rod cylinder in FIG.

As shown in FIG. 1, an engine valve actuator according to an embodiment of the present invention includes an exhaust valve 4 a serving as an engine valve and an air supply as the combustion piston 3 moves up and down in a cylinder block 2 of an internal combustion engine 1. The valve 4b is driven.
Each of the exhaust valve 4 a and the air supply valve 4 b is fixed to the lower end of the valve rod 5, and is urged in the valve closing direction by a valve spring 6 provided on the valve rod 5.

A valve driving device 10 is provided at the tip of each valve rod 5.
The valve driving device 10 includes a valve driving cylinder 11, a valve driving piston 12 movably accommodated in the valve driving cylinder 11, a servo valve 13 for driving the valve driving piston 12, and positions of the valve driving piston 12. And a displacement meter mounting base 14 that also serves as an upper lid of the valve drive cylinder 11.

<Configuration of valve drive device>
Next, a detailed configuration of each valve driving device 10 will be described with reference to FIG.
As shown in FIG. 2, a valve drive piston 12 that can move up and down is accommodated in the valve drive cylinder 11.
A rod through hole 18 is formed in the lower center of the valve drive cylinder 11, and the valve rod 5 is inserted in the rod through hole 18 in a fluid-tight manner so as to be movable up and down.
The tip of the valve rod 5 penetrating the rod through hole 18 is connected to the lower surface of the valve drive piston 12.

A space between the lower inner surface of the valve drive cylinder 11 and the lower surface of the valve drive piston 12 is a valve drive cylinder lower chamber 11b.
At this time, the piston lower surface area A2 is obtained by dividing the cross sectional area of the valve drive piston 12 by the cross sectional area of the valve rod 5.

A piston central recess 17 is formed on the upper surface of the valve drive piston 12.
At this time, the space between the periphery of the upper surface of the valve drive piston 12 and the bottom of the piston central recess 17 and the lower surface of the displacement meter mounting base 14 also serving as the upper cover of the valve drive cylinder 11 becomes the valve drive cylinder upper chamber 11a. ing.
Several targets 16 for measuring the position of the valve drive piston 12 are attached to the side surface of the piston central recess 17 in the moving direction of the valve drive piston 12.

A displacement meter mounting base 14 that also serves as an upper cover of the valve drive cylinder 11 is liquid-tightly attached to the upper portion of the valve drive cylinder 11.
A displacement gauge insertion hole 19 is formed in the center of the displacement gauge mount 14.
The displacement meter 15 is attached to the displacement meter mounting base 14.
The distal end of the displacement meter 15 is inserted into the displacement meter insertion hole 19, extends into the piston central recess 17 of the valve drive piston 12, and faces the target 16.
The position of the valve drive piston 12 is measured by measuring the position of the target 16 with the displacement meter 15.

At this time, the gap between the side inner surface of the piston central recess 17 and the outer periphery of the displacement meter 15 is kept at a sufficient distance so as not to inhibit or suppress the flow of the drive oil.
Therefore, the piston upper surface area A1 on which the drive hydraulic pressure acts is the sum of the area A1a around the piston central recess 17 of the valve drive piston 12 and the bottom area A1b of the piston central recess 17.
In this case, the piston upper surface area A1> piston lower surface area A2.
On the other hand, in the double rod cylinder type as in Patent Document 2, the piston upper surface area is equal to the piston lower surface area.

<Configuration of servo valve>
A servo valve 13 is attached adjacently to the outer side surface of the valve drive cylinder 11.
In FIG. 2, the three-way switching control valve 22 is schematically illustrated, but is actually configured by a spool, an oil passage, an electromagnetic coil, and the like as is well known.

The outlet of the three-way switching control valve 22 is connected to the valve drive cylinder upper chamber 11a via the valve opening hydraulic passage 20.
One of the inlets of the three-way switching control valve 22 is connected to the valve drive cylinder lower chamber 11b via the hydraulic pressure supply passage 21.
The hydraulic pump 24 is connected to the hydraulic pressure supply passage 21 via the oil supply pipe 23.
Further, an oil drain pipe 25 is connected to the other inlet of the three-way switching control valve 22.

The valve driving device 10 is configured as described above. When the valve rod 5 is pushed out, the three-way switching control valve 22 is switched to the B port side so that the hydraulic oil from the hydraulic pump 24 is supplied to the oil supply pipe 23 and the hydraulic pressure supply. It is supplied to the valve drive cylinder upper chamber 11a through the passage 21, the three-way switching control valve 22, and the valve opening hydraulic passage 20.
At this time, the hydraulic pressure supply passage 21 also communicates with the valve drive cylinder lower chamber 11b, and hydraulic fluid flowing out from the valve drive cylinder lower chamber 11b is also supplied to the hydraulic pressure supply passage 21, the three-way switching control valve 22, and the valve opening hydraulic passage. 20 to the valve drive cylinder upper chamber 11a.

Conversely, when the valve rod 5 is pushed out, the three-way switching control valve 22 is switched to the A port side at the time of pulling, so that the hydraulic oil from the hydraulic pump 24 passes through the oil supply pipe 23 and the hydraulic pressure supply passage 21 (three-way). It is supplied to the valve drive cylinder lower chamber 11b (without going through the switching control valve 22).
The hydraulic fluid that has flowed out of the valve drive cylinder upper chamber 11 a is discharged to the outside through the valve opening hydraulic passage 20, the three-way switching control valve 22, and the oil drain pipe 25.

<Description of operating principle>
The operating principle of the single-rod cylinder type engine valve actuator according to the embodiment of the present invention is as follows. If it is generated in the above, it will be explained which supply energy is larger.

In general, the flow rate characteristic of a servo valve is expressed by the following equation (1).
Q = Qo√ (ΔP / Po) (1)
In addition,
Po: Reference pressure,
Qo: reference flow rate,
ΔP: pressure dropped due to passing through the three-way switching control valve,
Q: Flow rate at pressure ΔP.

At the time of pushing, the respective pressures and flow rates are as shown in the following formulas 2 and 3.
Q1 = Qo√ {(Ps−Pl) / Po} (2)
V = Q1 / A1 = Qo / A1 · √ (1 / Po) · √ (Ps−P1) (3)
In addition,
Q1: Cylinder upper chamber inflow oil amount (at the time of extrusion),
Ps: hydraulic pump discharge pressure,
Pl: Cylinder upper chamber pressure (when pushing),
Q1: Cylinder upper chamber inflow oil amount (at the time of extrusion),
A1: Piston upper surface area,
V: piston moving speed.

In calculating the piston moving speed V, since the pressure drops by the three-way switching control valve 22, the cylinder upper chamber pressure P1 is unknown.
However, since the valve drive cylinder lower chamber 11b is directly connected to the hydraulic pump 24 (not via the three-way switching control valve 22), when an external force F is applied, F = P1, A1, P2, and A2. = P1 · A1-Ps · A2.
Therefore, the cylinder upper chamber pressure P1 is obtained by the following equation (4).
P1 = (F + Ps · A2) / A1 (4)
In addition,
F: External force
A2: Piston lower surface area (piston area during pulling).

On the other hand, in the double rod cylinder type as described in Patent Document 2,
Since piston upper surface area A1 = piston lower surface area A2,
F = A1 (P1-P2) (5)
It becomes.
Also, when servo valves are used for both rod cylinders, the amount of hydraulic oil entering the cylinder upper chamber and the amount of hydraulic oil exiting from the cylinder lower chamber are the same. ) Is as shown in Equation 9.
Ps-P1 = P2-0 (6)
P2 = Ps−P1 (7)
F = A1 (2 · P1-Ps) (8)
P1 = 1/2 · (F / A1 + Ps) (9)
Note that P2 is the cylinder lower chamber pressure (at the time of extrusion).

On the other hand, in the single rod cylinder type according to the embodiment of the present invention, when α = A2 / A1, the cylinder upper chamber pressure P1 is expressed by the following equation 10 from equation 4.
P1 = F / A1 + Ps · α (10)

In the single rod cylinder type and the double rod cylinder type, the speed at the time of extrusion is determined by the cylinder upper chamber pressure P1 from Equation 3.
Therefore, it will be examined whether the same cylinder upper chamber pressure P1 can be obtained under the same load condition in the single rod cylinder type and the double rod cylinder type.

If Equation 9 = Equation 10, it becomes as follows.
F / A1 + Ps · α = 1/2 · F / A1 + 1/2 · Ps
α = 1 / Ps (1/2 · Ps−1 / 2 · F / A1)
= 1 / (2 · Ps) · (Ps−F / A1) (11)
If F becomes 0 at the maximum speed as in the case of inertia load, α = 1/2 and the one of the single rod cylinder type and the double rod cylinder type are the same.

If α is determined according to the value of external force F / piston upper surface area A1 according to Formula 11, the same servo valve and the same push side area cylinder are used for the single rod cylinder type and the double rod cylinder type. Performance (= same speed when a load is applied) can be obtained.
If α can be further reduced, the single rod cylinder type can increase the speed and is efficient.

  It should be noted that α = 0 when the hydraulic pump discharge pressure Ps = external force F / piston upper surface area A1, but even in the double rod cylinder type, the cylinder upper chamber pressure P1 = hydraulic pump discharge pressure Ps from Formula 10, and from Formula 3. Since the piston moving speed V = 0, it does not function as a cylinder.

At the time of pulling, the cylinder speed V is expressed by the following equation 12,
V = Qo / A1 · √ (1 / Po) · √P1 (12)
The speed can be increased as the cylinder upper chamber pressure P1 is increased.
In this case, if α = A2 / A1 is selected according to Equation 11, the same performance is obtained.

In the single rod cylinder type according to the embodiment of the present invention, the pump discharge amount Qp for driving the combustion piston 3 is, as is apparent from FIG. 2, the valve drive cylinder lower chamber 11b when pushed. The oil on the discharge side is returned to the hydraulic supply passage 21, that is, the discharge port of the hydraulic pump 24, and is smaller than that of the double rod cylinder type.
At the time of pulling, in the case of a single rod cylinder, the piston lower surface area A2 <piston upper surface area A1, and it is clear that the required pump discharge amount Qp is small.

<Structure of three-way switching control valve>
Next, the structure of the three-way switching control valve 22 employed in the engine valve actuator according to the embodiment of the present invention will be described with reference to FIGS.
3 is a vertical end view of the three-way switching control valve in FIG. 2 and a plan view of the sleeve.
In addition, the upper half part (a) in FIG. 3 is a vertical end view of the three-way switching control valve, and the lower half part (b) is a plan view of the sleeve.

4 is a cross-sectional view taken along line AA in FIG.
5 is a cross-sectional view taken along the line BB in FIG.
5A is a first example of the sleeve oil pressure supply hole 45 and the sleeve oil drain hole 46, FIG. 5B is a second example, FIG. 5C is a third example, FIG. 5D shows a fourth example.

In the engine valve actuator described above, it is necessary to operate the small valve driving device 10 at a high speed, and it is necessary to use a large capacity three-way switching control valve 22 corresponding to the speed.
However, when the large three-way switching control valve 22 is used, the flow gain of the valve drive device 10 becomes high, so that the overall control gain cannot be made high (the control accuracy becomes low).
If the control gain cannot be increased, disturbances such as manufacturing errors, electrical noise, and mechanical noise of the three-way switching control valve 22 cannot be suppressed, and the positioning system is lowered.

  Therefore, as shown below, the shape of each hole in the sleeve that determines the capacity of the three-way switching control valve 22 is reduced so that the flow rate gain is reduced so that the width becomes narrower when the opening degree is small, which requires high accuracy. In the case of a large opening that requires a high speed, the flow rate gain is increased so as to increase the width, thereby configuring the three-way switching control valve 22 with high accuracy and large capacity.

As shown in FIG. 3, the three-way switching control valve 22 includes a cylindrical manifold block (housing) 30, a cylindrical sleeve 40 that is liquid-tightly fixed in the manifold block 30, and a liquid-tight inside the sleeve 40. The spool 50 is slid in the front-rear direction by an electromagnetic coil (not shown).
A hydraulic pressure supply port 32 connected to the hydraulic pressure supply passage 21 shown in FIG. 2 is formed on one side of the manifold block 30 (left side in FIG. 3).
A valve opening oil port 31 connected to the valve opening hydraulic passage 20 is formed in the center of the manifold block 30.
An oil drain port 33 connected to the oil drain pipe 25 is formed on the other side of the manifold block 30 (right side in FIG. 3).

A ring-shaped groove is formed on the outer peripheral surface on one side of the sleeve 40, and a ring-shaped supply communication chamber 42 is formed by the groove and the inner peripheral surface of the manifold block 30.
The supply communication chamber 42 communicates with the hydraulic pressure supply port 32 of the manifold block 30.
Furthermore, two hydraulic pressure supply holes 45 communicating with the supply communication chamber 42 are formed inside one side of the sleeve 40.

A ring-shaped groove is formed on the outer peripheral surface at the center of the sleeve 40, and a ring-shaped communication chamber 41 for valve opening is formed by this groove and the inner peripheral surface of the manifold block 30.
The valve opening communication chamber 41 communicates with the valve opening oil port 31 of the manifold block 30.
Further, 3 to 6 valve opening oil holes 44 communicating with the valve opening communication chamber 41 are formed inside the center of the sleeve 40.

In addition, a ring-shaped groove is formed on the outer peripheral surface of the other side of the sleeve 40, and a ring-shaped drainage communication chamber 43 is formed by this groove and the inner peripheral surface of the manifold block 30.
The oil discharge communication chamber 43 communicates with the oil discharge port 33 of the manifold block 30.
Further, two oil drain holes 46 communicating with the oil drain communication chamber 43 are formed inside the other side of the sleeve 40.

  A ring-shaped groove is formed on the outer peripheral surface of the spool 50, and a ring-shaped spool hole communication chamber 51 is formed by the groove and the inner peripheral surface of the sleeve 40.

Then, by driving the spool 50 to one side, the hydraulic oil from the hydraulic pump 24 illustrated in FIG. 2 is supplied to the hydraulic supply passage 21, the hydraulic supply port 32, the supply communication chamber 42, the hydraulic supply hole 45, the spool hole. It flows through the communication chamber 51, the valve opening oil hole 44, the valve opening communication chamber 41, the valve opening oil port 31, and the valve opening hydraulic passage 20, and is supplied to the valve drive cylinder upper chamber 11a shown in FIG. .
On the other hand, when the spool 50 is driven to the other side, the hydraulic fluid flowing out from the valve drive cylinder upper chamber 11a shown in FIG. 2 flows into the valve opening hydraulic passage 20, the valve opening oil port 31, and the valve opening communication. It flows through the chamber 41, the valve opening oil hole 44, the spool hole communication chamber 51, the oil discharge hole 46, the oil discharge communication chamber 43, the oil discharge port 33, and the oil discharge pipe 25 and is discharged to the outside.

Next, a first example of the shape of the hydraulic pressure supply hole 45 and the oil discharge hole 46 of the sleeve 40 will be described in detail with reference to FIGS. 4 and 5A.
In order to make the three-way switching control valve 22 highly accurate and have a large capacity, the oil pressure supply hole 45 and the oil discharge hole 46 of the sleeve 40 are shaped as follows.

The hydraulic pressure supply hole 45 (oil drain hole 46) includes a small opening part 45a (46a) on the tip side (oil passage start end side) and a gradually increasing opening part 45b (46b) continuous to the small opening part 45a (46a). ) And a large opening portion 45c (46c) continuous to the gradually increasing opening portion 45b (46b).
In the example illustrated in FIG. 5A, the gradually increasing opening 45b (46b) has a circumferential width that is linearly expanded.
Moreover, the small opening part 45a (46a) is located in the center of the circumferential direction of the large opening part 45c (46c).
Further, the side walls on both sides in the circumferential direction of the holes of the small opening portion 45a (46a), the gradually increasing opening portion 45b (46b) and the large opening portion 45c (46c) are not in the radial direction, as shown in FIG. , Parallel to the radial direction.

The longitudinal width ratio LL / LS between the circumferential width LS of the small opening portion and the circumferential width LL of the large opening portion varies depending on the pressure or the amount of hydraulic oil, but the longitudinal width ratio LL / LS = A range of 5 to 10 is preferable.
If the front / rear width ratio LL / LS is too small, the control accuracy decreases, and if the front / rear width ratio LL / LS is too large, the capacity at the start of operation decreases.

Next, second to fourth examples of the shape of the hydraulic pressure supply hole 45 (oil drain hole 46) will be described with reference to FIGS. 5 (b), 5 (c), and 5 (d).
In the second example of the hydraulic pressure supply hole 45 (oil discharge hole 46) shown in FIG. 5B, the gradually increasing opening degree 45b (46b) is not linear, but as it goes to the large opening degree 45c (46c). It is formed in a curved shape so that the opening rate is increased.

In the third example shown in FIG. 5C, the small opening portion 45a (46a) is eccentric, and one end wall in the circumferential direction of the small opening portion 45a (46a), the gradually increasing opening portion 45b. (46b) One end wall in the circumferential direction and one end wall in the circumferential direction of the large opening portion 45c (46c) are formed so as to coincide with the circumferential direction.
With this shape, the hydraulic oil that has flowed into the spool hole communication chamber 51 from the small opening 45a (46a) at the start of control does not collide with the spool 50 from the front in the spool hole communication chamber 51. It flows along the circumference.

  Further, depending on the capacity of the three-way switching control valve 22, the hydraulic pressure, and the type of control target device controlled by the three-way switching control valve 22, as shown in FIG. ) May be omitted, and the small opening portion 45a (46a) and the large opening portion 45c (46c) may be directly connected.

  Thus, by making the circumferential width on the front end side of the hydraulic pressure supply hole 45 (oil drain hole 46) smaller than the circumferential width on the rear end side, the three-way switching control valve 22 with high accuracy and large capacity can be provided. Obtainable.

<Other embodiments>
As mentioned above, although each embodiment of this invention was described, it cannot be overemphasized that this invention is not limited to each said embodiment, A various change may be added within the scope of the present invention.

<Effect>
According to the engine valve actuator of the single rod cylinder type according to the embodiment of the present invention, by selecting the area ratio α between the piston upper surface area A1 and the piston lower surface area A2 optimally, Despite obtaining the same performance, the energy supplied from the hydraulic pump 24 can be reduced.
Of course, in the single rod cylinder type, since the displacement meter is housed in the valve drive cylinder 11, it is not necessary to protrude the rod to the side opposite to the exhaust valve 4a and the intake valve 4b side, and the conventional double rod cylinder type Compared to the above, the overall dimensions of the valve drive device 10 can be reduced, and there is also a functional merit.

Further, since the displacement meter is incorporated in the valve drive cylinder 11, a sliding seal is not necessary.
In addition, the required energy for pushing and pulling can be set optimally according to the load, and a part of the energy when pushed, which is absolutely impossible with the conventional double rod cylinder type, can be recovered.
Further, there is no leakage of hydraulic oil from the intake / exhaust valve control side (note that there is no problem because the exhaust valve 4a and the supply valve 4b side burn together with the engine fuel even if some hydraulic oil leaks).

DESCRIPTION OF SYMBOLS 1 Internal combustion engine 2 Cylinder block 3 Combustion piston 4a Exhaust valve 4b Supply valve 5 Valve rod 6 Valve spring 10 Valve drive device 11 Valve drive cylinder 11a Valve drive cylinder upper chamber 11b Valve drive cylinder lower chamber 12 Valve drive piston 13 Servo valve DESCRIPTION OF SYMBOLS 14 Displacement meter mounting base 15 Displacement meter 16 Target 17 Piston center recessed part 18 Rod through hole 19 Displacement meter insertion hole 20 Hydraulic opening passage 21 Hydraulic supply passage 22 Three-way switching control valve 23 Oil supply piping 24 Hydraulic pump 25 Oil discharge piping 30 Manifold block 31 Valve opening oil port 32 Hydraulic supply port 33 Oil discharge port 40 Sleeve 41 Valve opening communication chamber 42 Supply communication chamber 43 Oil discharge communication chamber 44 Sleeve oil opening oil hole 45 Sleeve oil supply hole 45a Small Opening part 45b Gradually increasing opening part 45c Large opening part 46 Oil drain hole 46a Small opening part 46b Gradual opening part 46c Large opening part 50 Spool 51 Spool hole communication chamber Qo Reference flow rate Q Flow rate at valve drop pressure ΔP Q1 Cylinder upper chamber inflow oil amount Q2 Cylinder lower chamber outflow Oil amount Qs Hydraulic pump discharge oil amount Qp Pump discharge amount Po Reference pressure Pl Cylinder upper chamber pressure P2 Cylinder lower chamber pressure Ps Hydraulic pump discharge pressure A1 Piston upper surface area A2 Piston lower surface area F External force V Piston moving speed LS Width in the circumferential direction LL Width in the circumferential direction of the large opening

Claims (3)

In an engine valve actuator that drives an engine valve of an internal combustion engine,
A valve drive cylinder having a rod through hole drilled on the engine valve side;
A valve rod inserted through the rod through hole;
A valve drive piston attached to one end of the valve rod;
A three-way switching control valve mounted adjacent to the side of the valve drive cylinder;
A valve opening hydraulic passage connecting the valve drive cylinder upper chamber on the upper surface side of the valve drive piston and the three-way switching control valve;
A hydraulic supply passage for supplying hydraulic oil from a hydraulic pump to the three-way switching control valve;
A valve drive cylinder lower chamber on the lower surface side of the valve drive piston is connected to the hydraulic pressure supply passage ;
The three-way switching control valve is
A sleeve fixed in the manifold block;
A spool that slides within the sleeve;
The hole for controlling the amount of hydraulic oil to the spool hole communication chamber formed on the outer peripheral surface of the spool is formed such that the circumferential width on the front end side is smaller than the circumferential width on the rear end side. And engine valve actuator. A piston central recess formed in the center of the upper surface of the valve drive piston;
A target attached to an inner surface of the piston central recess;
The engine valve actuator according to claim 1, further comprising a displacement meter inserted so as to face the target from an upper lid of the valve drive cylinder. A cylinder block;
A combustion piston that moves up and down in the cylinder block;
An exhaust valve and an intake valve;
An internal combustion engine comprising: the engine valve actuator according to claim 1 or 2 that drives the exhaust valve and the air supply valve.

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