JPH0115740B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a neutral valve device, and in particular to a fluid pressure transmission device in which a fluid pump and a fluid motor are connected through a closed fluid main circuit and a push-in circuit is provided for supplying fluid to the main circuit. This invention relates to a check valve/neutral valve device which is applied to a fluid pressure transmission device and has a check function to appropriately connect and disconnect a main circuit and a pushing circuit when a fluid pressure transmission device is in a transmission state to obtain a neutral state.

Generally, in order to obtain a neutral state of a fluid pressure transmission device, it is sufficient to reduce the discharge of pressure oil from a fluid pump to zero, but the components that control the discharge flow rate of a fluid pump (for example, in the case of an axial piston type pump, the piston It is practically difficult to maintain the swash plate (which changes the stroke range) in a neutral state with zero discharge flow rate because there is play in the link mechanism or variations in the neutral position due to manufacturing errors in parts. Therefore, it has been proposed to connect the discharge side circuit and the suction side circuit of the fluid closed main circuit by mechanically interlocking a valve device attached thereto so as to operate the discharge flow rate control member near the neutral state. However, it not only requires a mechanism for interlocking the valve devices, but also has the disadvantage that the valves and oil passages are complicated. Additionally, the check valve device is usually provided as a separate component, further complicating the circuit.

The present invention relates to a valve hole that communicates with a main circuit of a fluid pressure transmission device, a through hole that is formed concentrically with the valve hole and has a valve seat, and that communicates with a push circuit of a fluid pressure transmission device, etc. A valve body having a conical valve head that is slidably disposed within the hole and engages with a valve seat formed in the through hole, a first spring that presses the valve body toward the valve seat, and the first spring. A second spring is provided that presses the valve body opposite to the first spring, and the balance of the forces of the two springs allows the valve head to be separated from the valve seat by a predetermined amount, thereby achieving a check valve function and a neutral valve. It is an object of the present invention to provide a check valve/neutral valve device which has a structure that has both a valve function and a simple and accurate operation.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 shows a fluid pressure transmission device incorporating a check valve/neutral valve device 1a, 1b according to the present invention, in which a fluid pump 3 driven by a prime mover 2 and a fluid motor linked to a driven member are shown. 4 are connected by closed main circuits 5 and 6. A push pump 8 driven by the prime mover 2 and a pressure regulating valve 9 are disposed in a push circuit 7 for supplying or replenishing fluid to the closed main circuits 5 and 6. , 6, there is a neutral valve device 1 that also serves as a check valve.
a and 1b are arranged. Also, closed main circuits 5, 6
are provided with relief valves 5a and 6a that maintain the maximum operating pressure in these main circuits at a predetermined pressure. The relief valves 5a, 6a are normally balanced piston type relief valves.

FIG. 2 is a sectional view of a hydraulic circuit block member 10 incorporating check valve/neutral valve devices 1a and 1b (hereinafter simply referred to as a valve device) according to the present invention.
Two identical valve devices 1a and 1b are arranged facing each other. This hydraulic circuit block member 10 is usually attached to a hydraulic transmission device or the like.

The configuration of one valve device 1a (the second left portion in the figure) will be described below. The hydraulic circuit block member 10 has a push-in side port 1 connected to the push-in circuit 7.
1 and a main circuit side port 12 connected to the main circuit, and a cylindrical hole 14 is bored from the end surface 13 on the left side in the drawing toward the push side port 11. A through hole 16 communicating with the push-in side port 11 is bored concentrically with the cylindrical hole 14 at the right end bottom 15 of the cylindrical hole 14 . The left corner (on the cylindrical hole 14 side) of the through hole 16 becomes a valve seat 17. The cylindrical hole 14 is provided with a chamber 18 formed in the shape of a bore, and the cylindrical hole 14 and the passage 12 communicate with each other via the chamber 18 . A sleeve member 20 is fitted into the cylindrical hole 14 at its outer diameter 21, and is kept liquid-tight by a seal member 20a and prevented from coming off by a stopper 19. A valve hole 22 is formed inside the sleeve member 20 concentrically with the through hole 16, and the valve hole 22 has a frusto-conical valve head 25 that can abut and engage with the valve seat 17. A valve body 26 is slidably fitted therein, and a notch 27 is provided on the side of the valve body to form a passage between the valve body and the valve hole 22 . The sleeve member 20 is also provided with a through hole 23 that communicates between the chamber 18 and the inside of the valve hole 22 . The valve body 26 includes a first and second spring 28 that presses the valve body toward the valve seat, and a second spring 2 that presses the valve body 26 in opposition to this spring.
9, the valve head 25 is normally assembled with the valve head 25 separated from the valve seat 17 by an amount X in the axial direction. This allows the push-in side port 11 and the main circuit side port 12 to communicate with each other. The other valve device 1b
(the first right-hand portion in the figure) is the same as the one valve device 1a, and will therefore be omitted.

Next, the operation of the valve devices 1a and 1b shown in FIG. 2 will be explained together with the fluid pressure transmission device shown in FIG.
A fluid pump 3 and a push pump 8 are driven by the prime mover 2, and a predetermined pressure _P1 is supplied to the push circuit 7. It is now assumed that the displacement changing means 3a of the fluid pump 3 is slightly deviated from the neutral position and is discharging pressure oil to the main circuit 6, and the fluid motor 4 is stopped. Pressure oil in the pushing circuit 7 passes through the valve device 1a at the upper side in the first figure (the left side in the second figure) and enters the main circuit 5.
supplied to In addition, the pressure oil discharged to the main circuit 6 is transferred to the valve device 1b at the lower side in the first figure (the right side in the second figure).
As shown in the second diagram, the valve opening degree
Since it is separated from the valve seat 17, it passes through the valve device 1b and returns to the push circuit 7. Therefore, the pressure _P3 in the main circuit 6 does not rise until the fluid motor 4 is driven, and so-called creep is prevented.

Next, the discharge flow rate to the main circuit 6 is increased by increasing the rotational speed of the prime mover 2 or by operating the displacement changing means 3a of the fluid pump 3, or by performing both operations simultaneously.
As Qp increases, the pressure _P3 increases, assuming that the valve opening X of the valve device 1b on the right side of FIG. The flow rate Q ₂ also increases. Furthermore, the discharge flow rate Qp
When the pressure increases, the pressure _P3 also increases, and when a predetermined set pressure (for example, a pressure that can drive the fluid motor 4 or a pressure slightly lower than that) is reached, the pressing force of the spring 28 and the pressure _P3 in the valve device 1b are increased. Therefore, if the sum of the forces pressing the valve body 26 exceeds the sum of the forces pressing the valve body 26 due to the pressing force of the spring 29 and the pressure _P1 , the balance of the forces acting on the valve body 26 will be lost. , the valve body 26 is displaced to the left in the second figure, and the valve opening degree X
decreases, the valve head 25 finally comes into abutting engagement with the valve seat 17, and the flow rate Q ₂ flowing back from the main circuit 6 to the pushing circuit 7 through the valve position 1b becomes zero. The pressure _P3 becomes sufficient to drive the fluid motor 4, and the fluid motor 4 begins to rotate, for example, the wheels of the vehicle rotate, and the vehicle starts moving. At this time, the pressure P ₃ in the main circuit 6 is:
It corresponds to the load, that is, the force required to drive the vehicle.

On the other hand, the fluid pump ₃ discharges the fluid in the main circuit 5 to the main circuit 6, and the discharge flow rate Qp increases, so that the pressure P 2 in the main circuit 5 decreases from the initial value, and the pressure in the pushing circuit 7 decreases. _P1 , and the difference becomes larger as the discharge flow rate Qp increases. (However, it is assumed that the valve opening degree X of the valve device 1a is maintained at the state shown in the second diagram and does not change.) As a result, the pushing flow rate _Q1 from the pushing circuit 7 to the main circuit 5 through the valve device 1a increases. do. If there is no internal leakage in the fluid pump 3, fluid motor 4, and valve devices 1a and 1b, this push _- in flow rate Q1 will be the same as the return flow rate _Q2 .
In this state, when the difference between the pressure P ₂ and the pressure P ₁ reaches a predetermined value, the sum of the pressing force of the spring 28 and the force pressing the valve body 26 due to the pressure P ₂ in the valve device 1a becomes the force of the spring 29. The pressing force and the pressure _P1 become smaller than the sum of the forces pressing the valve body 26, and the valve body 26 is displaced to the left in the second figure, and the valve opening degree X increases. This increases the pushing flow rate _Q1 . Then,
As described above, when the valve device 1b closes the valve opening X and the return flow rate _Q2 becomes zero, the push-in flow rate _Q1 also becomes zero, and the pressure _P2 in the main circuit 5 is approximately the same as the pressure _P1 in the push-in circuit 7. becomes. If there is internal leakage from the fluid pump 3, fluid motor 4, and valve devices 1a and 1b, fluid is replenished from the push circuit 7 to the main circuit 5 through the valve device 1a by the leakage amount.

Among the state changes described above, the flow rate change is expressed as shown in FIG. 4. In this time-series diagram, the flow rate Qn when the recirculation flow rate _Q2 starts to decrease is determined by manufacturing errors of parts, displacement change means of the fluid pump, as understood from the above explanation of the valve device 1b. Considering the pump discharge flow rate corresponding to the amount of deviation of the neutral position due to play in the link system that operates It is determined by appropriately determining the dimension d2, the valve opening degree, the diameter _d1 of the through hole, etc.

In the above, the fluid pump 3 is connected to the main circuit 5 in FIG.
The operation of the valve devices 1a and 1b has been explained assuming that fluid is discharged from the main circuit 6 to the main circuit 6.
When discharging fluid from to 5, valve devices 1a, 1
Since the operation of b is simply reversed and is easily understood, the explanation will be omitted. The operation of the valve devices 1a and 1b is reversed even in an engine braking state such as when applied to a vehicle.

Next, the characteristics of the valve devices 1a and 1d will be explained.

Check valve characteristics: Relationship between push flow rate Q ₁ from push-in side port to main circuit side port and pressures P ₁ and P ₂ .

In FIG. 2, assuming that the valve device 1a operates as described above, the initial setting value (installed state) of the valve opening degree X is set _to If it is half of 2φ, the pushing flow rate Q ₁ is expressed as follows.

Further, the balance of forces acting on the valve body 26 is expressed as follows.

Where, Ca: flow coefficient, d ₁ : diameter of valve seat opening [cm],
φ: Fluid outflow angle [deg], X′: Valve opening displacement [cm], X ₀ : Initial setting valve opening [cm], ρ: Fluid density [Kg・s ² /cm ⁴ ], ΔP ₁ : Differential pressure (P ₁ − P ₂ )
[Kg/cm ² ], A: Pressure receiving area of the valve (πd ₁ ² /4)
[cm ² ], k ₁ : Spring constant of spring 28 [Kg/
cm], k ₂ : Spring constant of the spring 29 [Kg/cm]. Substituting equation (1) into equation (2) from these, ΔP ₁ = X′・(k ₁ +k ₂ )/A−Ca・π・d
₁・(X ₀ +X′)・sin2φ(3). The above relationship is illustrated in FIG. 5.

Neutral valve characteristics: Relationship between the return flow rate Q ₂ from the main circuit side port to the push side port and the pressures P ₃ and P ₁ .

In FIG. 2, assuming that the valve device 1b operates as described above, the initial setting value (installed state) of the valve opening degree X is set _to If it is half of 2φ, the recirculation flow rate Q ₂ is expressed as follows.

Further, the balance of forces acting on the valve body 26 is expressed as follows.

Where, Cb: Flow coefficient, d ₁ : Diameter of valve seat opening [cm],
φ: Fluid inflow angle [deg], X′: Valve opening displacement [cm], X ₀ : Initial setting valve opening [cm], ρ: Fluid density [Kg・s ² /cm ⁴ ], ΔP ₂ : Differential pressure (P ₃ − P ₁ )
[Kg/cm ² ], A: Pressure receiving area of the valve (πd ₁ ² /4)
[cm ² ], k ₁ : Spring constant of spring 28 [Kg/
cm], k ₂ : Spring constant of the spring 29 [Kg/cm]. Substituting equation (4) into equation (5) from these, ΔP ₂ = −X′・(k ₁ +k ₂ )/A−Cb・π
・d ₁・(X ₀ +X′)・sin2φ. The above relationship is illustrated in FIG. 6. As is clear from this, when the differential pressure exceeds a predetermined value, the recirculation flow rate Q ₂ decreases and finally reaches zero.
It is understood that the valve device 1b closes the valve opening.

Next, another embodiment of the present invention will be described with reference to FIGS. 7 and 8. FIG. 7 shows a fluid pressure transmission device incorporating a check valve/neutral valve 100 according to the present invention, and parts that are the same as or equivalent to those shown in FIG. 1 are designated by the same reference numbers as in FIG. The detailed explanation will be omitted. In the check valve/neutral valve 100, check valve/neutral valve devices 100a and 100b are disposed facing each other in a block member 110. This valve device 100a, 1
00b differs from the valve devices 1a and 1b shown in the second diagram only in a part of the configuration, and only the differences will be described below. Parts that are the same as or equivalent to the valve devices 1a and 1b shown in FIG. 2 are numbered the same as in FIG. 2, and in particular, the numbers are increased by 100. The push-in side port 111 has a valve device 100a,
It serves as a common port for the through holes 116, 116 of 100b. The through holes 116, 116 are bored approximately on the same axis. The valve devices 100a and 100b have valve heads 1 of valve bodies 126 and 126 arranged oppositely.
The end surfaces of the extending portions 27, 27 extending from the valve heads 125, 125 can come into contact with each other, and the valve heads 125, 125
The normal state shown in the figure is achieved by balancing the biasing forces of the springs 128 and 128 that press the valve seats 117 and 117, respectively. In this case, the valve openings X, X are set by determining the lengths of the end surfaces of the extensions 27, 27 from the valve heads 125, 125, taking into consideration the dimension S between the valve seats 117, 117. I can do it. (However, this assumes that the conical apex angle 2φ of the valve heads 125, 125 is constant.) In such a configuration, when looking at the valve body 126 of the valve device 100a as a reference, the spring 128 on the left side in the figure is the first spring. It becomes a repellent member, and the right spring 128 becomes a second spring. Moreover, when the valve body 126 of the valve device 100b is used as a reference, the spring 128 on the right side in the figure becomes the first spring, and the spring 128 on the left side becomes the second spring. The operation of the above configuration will be understood from the explanation of FIGS. 1 to 6 above, and will therefore be omitted. Note that when the valve device 100a or 100b functions as a check valve, the end surfaces of the extending portions of the valve bodies facing each other may be separated from each other. Further, when the valve devices 100a and 100b function as neutral valves, for example, when the valve body of the valve device 100b is displaced due to a pressure difference and the valve opening X becomes zero, the valve opening of the other valve device 100a becomes equal to the pressure. It opens at least to (x+X) regardless of the differential pressure between P ₁ and P ₂ .

FIG. 9 shows a modification of the embodiment shown in FIG. 8, in which the valve devices 100a and 100b in FIG.
Extending portions 27 extending from the valve heads 125, 125,
27 is replaced with plungers 30, 30. The plunger members 30, 30 are provided with stopper flanges 31, 31 at their axially intermediate portions.
It is slidably fitted into cylinders 35, 35 bored in 225. The open ends of the cylinders 35, 35 communicate with the chambers on the valve holes 222, 222 side of the respective valve devices 200a, 200b. Therefore, when this check valve _/ neutral valve 200 is applied to the fluid pressure transmission device _shown in FIG.
226 is displaced, one closes the valve opening, the other opens the valve further, and the plunger 30 further opens the valve head 22.
The valve opening degree for projecting and displacing the other plunger 30 relative to 5 is further opened. This point is different from those shown in Figures 2 and 8,
Other functions will be understood from the above description of the functions, and will therefore be omitted. In addition, the valve device 1 shown in the second figure
Parts that are the same as or equivalent to a and 1b are numbered the same as in FIG. 2, and in particular, 200 is added to the number.

FIG. 10 shows another modification of the embodiment shown in FIG. 8, in which the valve devices 100a, 1 of FIG.
Relief valve devices 50a and 66 are installed on the back of 00b, respectively.
0a is added. The relief valve devices 50a and 60a are the same, and the right side 60a in the figure will be described below. Relief valve device 60
a is a balanced piston type relief valve, which includes a sleeve member 32 screwed onto a block member 310;
0 together with the valve device 300b.
Valve hole 61 provided at the back of the valve hole 322 on the right side in the figure
A main valve 62 is slidably fitted into the main valve 62, and an orifice 63 is provided in the main valve 62. A main valve spring 64 is elastically mounted on the right side of the main valve 62, and is attached by a stopper 64 or a retaining ring 65 to restrict the leftward protrusion of the main valve 62. A drain port 66 is opened in the valve hole 61 and communicates with the push-in circuit 7 via a through hole 67. A chamber 68 formed in the valve hole 61 is communicated with a chamber 70 via an orifice 69, and a pilot valve 71 is connected to the orifice 6 by a spring 72 in the chamber 70.
It is arranged to block 9. The chamber 70 communicates with the push-in circuit via a relief passage 73. 74 is an adjuster for adjusting the load of the spring 72;
5 is a rock nut. Note that 76 and 77 are seal members. The other configurations are substantially the same as those shown in FIG. Regarding the numbering, parts that are the same as or equivalent to the members shown in the second figure are numbered as shown in FIG. 2, and in particular, 300 is added to the numbering. The operation of such a component device will be easily understood from the above-mentioned explanation of FIG. 2, and will therefore be omitted. For reference, the experimental results of the apparatus shown in FIG. 10 are attached.

FIG. 11 is a diagram showing the experimental results of check valve characteristics, which were measured under the conditions shown in FIG. 12. As a condition, hydraulic oil: Etsonutoh
HP32, oil temperature (θ): 30-39℃, d ₁ : 1.0cm, x+
X: 0.4cm, 2φ: 40deg, spring constant: 0.2
Kg/mm, spring initial (as shown) deflection:
It was set to 13mm.

FIG. 13 is a diagram showing the experimental results of the neutral valve characteristics, which were measured under the condition shown in FIG. 14. As a condition, hydraulic oil: Etsu Nutoh HP32,
Oil temperature (θ): 29: 33℃, d ₁ : 1.0cm, x=X: 0.2
cm, 2φ: 40deg, spring constant: 0.2Kg/mm,
The initial deflection of the spring (as shown) was 6.5 mm, and the flow rate Q ₂ was measured by gravimetry.

As explained in detail above, according to the present invention, there is a valve hole that communicates with the main circuit of a fluid transmission device, etc., a valve seat formed concentrically with the valve hole, and a valve seat that communicates with a push-in circuit of the fluid transmission device, etc. a conical valve head that is slidably disposed within the valve hole and engages with a valve seat formed in the through hole; and a valve body that presses the valve body toward the valve seat. 1 spring, and this first
A second valve that presses the valve body oppositely to the spring.
By installing a spring and separating the valve head from the valve seat by a predetermined amount by balancing the forces of these two springs, a check valve function that connects the circuit when pushing fluid from the push circuit to the main circuit can be achieved. ,
It is also possible to provide a neutral valve function for preventing so-called vehicle dragging by circulating the discharge flow rate of the fluid pump in its neutral state from the main circuit to the pushing circuit. In addition, by appropriately setting the spring constants of the two springs, the initial deflection at the time of installation, and the initial valve opening degree, the valve closing timing of the neutral valve characteristic can be easily set to suit the unfavorable circumstances of the fluid pump's neutral state. I can do it. Furthermore, since the neutral valve is automatically closed in response to changes in the differential pressure between the push-in pressure and the main circuit pressure, there are other advantages such as the ability to start the vehicle smoothly without the need for any linkage mechanism. It has a great effect.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram of a fluid transmission device to which the check valve/neutral valve device according to the present invention can be applied, Fig. 2 is a cross-sectional view showing an embodiment of the present invention, and Fig. 3 is a cross-sectional view taken along the line of Fig. 2. Figure 4 is a time series diagram, Figure 5 is a check valve characteristic diagram, Figure 6 is a neutral valve characteristic diagram, and Figure 7 is a time series diagram.
8 is a sectional view showing another embodiment of the invention, FIG. 9 is a sectional view showing a modification of the invention, and FIG. FIG. 10 is a sectional view showing another modification of the present invention, the first
Figure 1 is a characteristic diagram showing the experimental results of check valve characteristics.
FIG. 12 is a state diagram showing the method and apparatus, FIG. 13 is a characteristic diagram showing the experimental results of the neutral valve characteristics, and
FIG. 4 is a state diagram showing the experimental method apparatus. 22: Valve hole, 16: Through hole, 26: Valve body, 28:
1st spring, 29: 2nd spring.

Claims (1)

[Scope of Claims] 1. A fluid pump and a fluid motor are connected through a closed fluid main circuit, and 2. It also has a check valve function provided in a fluid transmission device, etc., which is provided with a push-in circuit that supplies fluid to the main circuit. In a neutral valve device having two valve devices, a valve hole formed in a sleeve member fitted into the valve device and communicating with a main circuit of a fluid pressure transmission device, etc.; A through hole is formed in a block member for a hydraulic circuit that communicates with a push-in circuit of a fluid pressure transmission device, etc., and has a diameter smaller than the diameter of the valve seat, and a corner portion thereof serves as a valve seat. a valve body having a truncated conical valve head that is capable of abutting engagement with the valve seat and interrupting communication with the main circuit and the pushing circuit; a sleeve member that biases the valve body toward the valve seat; and a first spring compressed between the valve body, and a first spring compressed between the valve body and a hydraulic circuit block member so as to oppose the first spring and bias the valve body in the direction of the first spring. The valve head is separated from the valve seat by a predetermined amount by a balance between the biasing forces of the first and second springs, and the valve body is positioned in a normal state where the main circuit and the push-in circuit are communicated with each other. A neutral valve device that also serves as a check valve. 2. The check valve/neutral valve device according to claim 1, wherein one of the valve devices introduces fluid from the push-in side passage and leads it out to the main circuit side. 3. The other valve device is characterized in that the fluid is introduced from the main circuit side and led out to the push circuit side,
A check valve/neutral valve device according to claim 1.