JPH0247601B2 - - Google Patents

Description

[Detailed description of the invention]

Technical Field The present invention relates to a triple piston cylinder device, and in particular, when the force for displacing a piston rod becomes small in relation to the pressure receiving area, the reduction in pressing force is prevented by partially increasing the pressure receiving area. The present invention relates to a triple piston cylinder device capable of reliably stopping a piston rod at four predetermined positions while equalizing the force for displacing the piston rod. Prior Art In a conventional single piston cylinder device, the piston rod fixed to the piston can be reliably stopped at two points;
There is a drawback in that it is not possible to reliably stop the motor at a four-point position, which is a four-point position plus two intermediate positions, for example, a four-point position required for an automatic gear change operation of a transmission. For example, as disclosed in Japanese Patent Application Laid-Open No. 59-159405, a cylinder device with a plurality of pistons that can slidably accommodate a plurality of pistons that can be displaced relative to each other in a cylinder and can output four-point positions. However, if the inner diameter of the cylinder is made the same throughout the piston's entire movable range, the force for displacing the piston rod may become particularly small in relation to the pressure-receiving area. , the outer diameter of each piston must be increased, resulting in a disadvantage that the cylinder device becomes larger and heavier. Purpose The present invention has been made to eliminate the drawbacks of the prior art described above, and its purpose is to accommodate a triple piston in a cylinder so as to be relatively displaceable. To surely stop a piston rod at four points with a simple configuration. Another object is to enable a single cylinder device to perform a selection operation for a transmission having four selection positions. Still another object is to partially increase the inner diameter of the cylinder to prevent a decrease in the pressure receiving area in the piston movable range where the force for displacing the piston rod is particularly small in relation to the pressure receiving area. It is an object of the present invention to equalize the force for displacement, thereby making it unnecessary to increase the dimensions of the piston rod and its related parts, and to provide a compact and lightweight cylinder device. Configuration In short, the present invention includes a cylinder, and a cylinder that is slidably housed in the cylinder, one end is open, the other end is sealed with a wall, and the diameter of the end with the wall is smaller than that of the other parts. an intermediate piston consisting of a hollow outer piston formed larger than a diameter; a first intermediate piston and a second intermediate piston slidably housed within the outer piston; a stopper mounted on the inner circumferential surface of the outer piston so as to be located between the second intermediate piston and to limit movement of both intermediate pistons;
an inner piston integrally formed with a piston rod that is slidably housed in the intermediate piston, passes through one end of the second intermediate piston, and slidably passes through one end of the cylinder; The diameter is _D0 , the diameter of the inner piston is _D1 , the diameter of the intermediate piston is _D2 , the diameter of the outer piston other than the end is _D3 , and the diameter of the end of the outer piston is _D4. In this case, there is a relationship of D ₄ > D ₃ > D ₂ > D ₁ > D ₀ , and the inner diameter of the movable range of the end of the outer piston opposite to the piston rod is smaller than that of the other portion. a first fluid port configured to be larger than the inner diameter of the piston rod and communicated with a hollow portion of the outer piston for displacing the outer piston toward the piston rod by a maximum amount; a second fluid port for displacing the outer piston, the second intermediate piston, and the inner piston by a maximum amount toward the piston rod; and a third fluid port for displacing the outer piston, the second intermediate piston, and the inner piston a maximum amount opposite the piston rod. a fluid port capable of setting the piston rod in a predetermined four-point position by relative displacement of the outer piston, the intermediate piston, and the inner piston and interaction with the outer piston wall and the stopper. and when the outer piston is displaced to the side opposite to the piston rod by the maximum amount, the pressing force is increased by increasing the pressure receiving area by increasing the diameter of the end portion. This feature is characterized in that it is configured so that it can be displaced. The present invention will be explained below based on embodiments shown in the drawings. The triple piston cylinder device 1 according to the present invention includes a cylinder 2, an outer piston 3, an intermediate piston 4 consisting of first and second intermediate pistons 4a and 4b, and an inner piston 5. The cylinder 2 has a sealed structure, and a hole 2b is formed at the right end 2a in the figure, through which a piston rod 5a integrally formed with the inner piston 5 slides through via a seal member 8. ing.
The cylinder 2 also has a first fluid port P1 for displacing the outer piston 3 by the maximum amount toward the piston rod 5a, and a first fluid port _P1 that communicates with the hollow portion 3a of the outer piston 3 to move the first intermediate piston 4a to the outer piston 3. A second fluid port _P2 for displacing the piston rod 5a by the maximum amount within the piston rod 5a side, and an outer piston 3
and a third fluid port _P3 for displacing the second intermediate piston 4b and the inner piston 5 by the maximum amount to the opposite side of the piston rod 5a.
Each of these fluid ports is connected to a fluid supply source (not shown) such as air or oil via a spool control valve (not shown) or the like. The outer piston 3 is slidably housed in the hollow part 2c of the cylinder 2 via a seal member 9, and is formed hollow, and the left end in the figure is connected to the wall part 3b.
A groove 3c communicating with the hollow portion 2c of the cylinder 2 is provided at the open right end in the figure. Further, in the lower part of the outer piston 3 in the figure, there is a groove 3d that communicates with the second fluid port _P2 and the hollow part 3a, a communication hole 3e that communicates with the groove and the hollow part 3a, and a communication hole 3e in the figure of the cylinder 2. A groove 3g communicating with the discharge hole 2e formed in the lower part is provided. The outer piston 3 is configured to be able to slide left and right within the cylinder 2 within a stroke l ₁ range. The first intermediate piston 4a is slidably housed in the outer piston 3 via a seal member 10, and is formed hollow, with a wall 4c formed at the left end in the figure. A hole 4d communicating with the hollow portion 3a of the outer piston 3 is formed in the outer piston 3.
Further, the stroke l 2 of the first intermediate piston 4a is regulated by the opening end 4e formed at the right end in the figure coming into contact with a stopper 12 buried in the middle part of the inner circumferential surface of the outer piston ₃ . It is becoming more and more common. It is designed to be able to slide left and right inside the outer piston 3 within the range of stroke _l2 . The second intermediate piston 4b is slidably housed in the outer piston 3 via a seal member 13, and is formed in the same shape as the first intermediate piston 4a, and is formed at the right end in the figure. A piston rod 5a passes through the hole 4g of the wall portion 4f.
Further, the second intermediate piston 4b has an open end 4h formed at the left end in the figure at the stopper 1 of the outer piston 3.
2, the stroke _l3 is regulated. and stroke
It is designed to be able to slide left and right inside the outer piston 3 within a range of _l3 . The inner piston 5 is slidably housed in the first and second intermediate pistons 4a and 4b via a sealing member 15, and can be used alone or in the second intermediate piston within the range of the sum of strokes _l3 and _l4 . It is designed to be able to slide left and right inside the outer piston 3 together with the piston 4b, and a piston rod 5a is integrally formed on the right side. and an outer piston 3 and an intermediate piston 4 consisting of first and second intermediate pistons 4a and 4b;
Due to the relative displacement with the inner piston 5, the piston rod 5a is moved to four predetermined positions Q ₁ , Q ₂ , Q ₃ and
It is configured so that it can be stopped at _Q4 . In addition, the cylinder 2 has an inner diameter (=diameter of the end 3f) D ₄ of the movable range (range of stroke l ₁ ) of the end 3f of the outer piston 3 opposite to the piston rod 5a.
is the inner diameter of other parts (=diameter of outer piston 3)
It is formed larger than D ₃ to increase the pressure receiving area when the outer piston 3 moves in the direction of the piston rod 5a. Effects The present invention is configured as described above, and its effects will be explained below. First, the case where the piston rod 5a is stopped at the rightmost first position _Q1 will be explained with reference to FIG. When fluid is allowed to flow into the first fluid port _P1 as shown by arrow _B1 , the outer piston 3 is displaced to the rightmost position and stops. At the same time, the fluid is transferred to the second fluid port P ₂ as shown by arrow B ₂
When the fluid flows into the hollow part 3a through the groove 3d and the communication hole 3e, the first intermediate piston 4a is displaced to a position where it hits the stopper 12 and stops, and the inner piston 5 is moved to the position where it hits the stopper 12. Together with the intermediate piston 4b, the wall portion 4f of the second piston moves to the rightmost position corresponding to the right end 2a of the cylinder 2 and stops. As a result, both the outer piston 3 and the inner piston 5 are displaced to the rightmost end and stopped, and the piston rod 5a is stopped at the first position _Q1 . Therefore, for example, by selecting this first position _Q1 , the transmission can be shifted to the fifth or sixth gear. Next, move the piston rod 5a to the intermediate second position Q ₂
The case where the motor is stopped will be explained with reference to FIG. While maintaining the state shown in FIG. 1, fluid is allowed to flow into the third fluid port _P3 as shown by arrow _B3 .
In this case, the pressure P of the fluid flowing into the first and third fluid ports P ₁ and P ₃ is the same, and the cross-sectional area of the portion of the hollow portion 2c of the cylinder 2 with an inner diameter of D ₄ is A ₄ ,
Assuming that the cross-sectional area of the other portion whose inner diameter is D ₃ is A ₃ and the cross-sectional area of the piston rod 5a is A ₂ , the force F ₁ that presses the outer piston 3 in the right direction in the figure is F ₁
= PA ₄ , and on the other hand, the force F ₂ that presses the outer piston 3 to the left in the figure is F ₂ = P (A ₃ - _{A 2} ) =
Since PA ₃ −PA ₂ and the cross-sectional area A ₄ > A ₃ , the force
F ₁ is greater than force F ₂ by an amount corresponding to P(A ₄ −A ₃ +A ₂ ). Therefore, the outer piston 3 is at rest, and the second intermediate piston 4b moves to the left to move the inner piston 5.
is pushed leftward, and the second intermediate piston 4b is displaced leftward within a stroke range of l ₃ -l ₁ until it hits the stopper 12 and stops. As a result, from the state shown in FIG. 1, the piston rod 5a has a stroke of l ₃ −l ₁
Move to the left by the amount of and stop at the second position _Q2 .
Thus, for example, by selecting the second position _Q2 , the transmission can be shifted into the third or fourth gear. Next, move the piston rod 5a to the third intermediate position Q ₃
The case where the motor is stopped will be explained with reference to FIG. When the supply of fluid from the second fluid port _P2 is stopped while maintaining the state shown in FIG. is displaced to the left within the range of stroke l ₂ until it hits the wall 3b of the outer piston 3 and then stops. As a result, the piston rod 5a moves to the left by the stroke l2 from the state shown in FIG. ₂ and stops at the third position _Q3 . Therefore, by selecting the third position _Q3 , for example, the transmission can be shifted to the first or second gear. Next, move the piston rod 5a to the leftmost fourth position.
The case of setting Q ₄ will be explained with reference to FIG. When the supply of fluid from the first fluid port P ₁ is stopped while maintaining the state shown in FIG.
It moves to the leftmost position until it hits g and stops.
At the same time, the inner piston 5 also becomes the first intermediate piston 4a.
is displaced to the left together with the outer piston 3. As a result, the outer piston 3 and the inner piston 5
Both are displaced to the leftmost position and stopped, and the piston rod 5a is stopped at the fourth position _Q4 . Therefore, by selecting the fourth position _Q4 , for example, the transmission can be shifted to reverse gear. As described above, the piston rod 5a is moved to four positions Q ₁ , Q ₂ ,
Make sure to stop at Q ₃ and Q ₄ . Here, the force F that displaces the piston rod 5a when it is displaced from each position Q ₁ , Q ₂ , Q ₃ , Q ₄ to another position will be explained. The diameter of the piston rod 5a is D ₀ , the diameter D ₁ of the inner piston 5 is mD ₀ ,
The diameter D ₂ of the intermediate piston 4 is mD ₀ + nD ₀ , the diameter D ₃ of the outer piston 3 is mD ₀ + 2nD ₀ , and the diameter D ₄ is also
kD ₃ (m, n and k are constants). Also, the first
It is assumed that the pressures P of the fluids flowing into the second and third fluid ports P ₁ , P ₂ , and P ₃ are all the same. When the piston rod 5a is displaced from the first position Q1 to _the second position _Q2 , from the second position _Q2 to the third position _Q3 , and from the third position _Q3 to the fourth position _Q4, the piston rod 5a
Let F ₁₂ , F ₂₃ , and F ₃₄ be the forces that displace the F ₁₂ = π/4 {(m+n) ² − m ² −1)} D ₀ ² P F ₂₃ = π/4 (m ² −1) D ₀ ² P F ₃₄ =π/4 {(m+2n) ² −1)}D ₀ ² P. Also, from the fourth position Q ₄ to the third position Q ₃ , the third position
Q ₃ to second position Q ₂ , second position Q ₂ to first position
Let F ₄₃ , F ₃₂ , and F ₂₁ be the forces that displace the piston rod 5a when they are displaced to Q ₁ respectively, then F ₄₃ = π/4 {(k ² −1) (m+2n) ² +1)}D ₀ ² P F ₃₂ =π/4 {(m+n) ² −m ² −1)}D ₀ ² P F ₂₁ =π/4m ² D ₀ ² P. Here, if the inner diameters D ₄ and D ₃ are the same,
Since F ₄₃ = π/4D ₀ ² P, by making the inner diameter D ₄ larger than D ₃ , the force F ₄₃ increases by π/4(k ² −1) (m+ 2n) ² D ₀ ² P. That's what I did. In the above formula, for example, m=2, n=1 or m=3, n=1, k=
By substituting 1.3 into each, it becomes as shown in Table 1.

[Table] Here, when the inner diameter D ₄ = D ₃ , the force F ₄₃ is F ₄₃ = π0.25D ₀ ² P in both the upper and lower rows of Table 1, so the inner diameter
By setting D ₄ = 1.3D ₃ , the force F ₄₃ increases by 18.24 times. As described above, move the piston rod 5a to the fourth position Q ₄
Even when the force for displacing the piston rod 5a is particularly small, such as when displacing the piston rod 5a from the piston rod 5a to the third position _Q3 , the inner diameter _D4 is made larger than the piston rod _D3 . The forces are equalized, especially the diameter of the piston rod 5a.
There is no need to increase D ₀ . Therefore, the diameters of the inner piston 5, intermediate piston 4, outer piston 3, and cylinder 2 do not need to be particularly large, so the cylinder device 1 becomes small and lightweight. Note that in the above description, the fluid may be air or oil. Effects Since the present invention is configured and operates as described above, the triple piston is accommodated in the cylinder so that it can be relatively displaced, so the piston rod can be reliably stopped at four points with a simple configuration. You can get the effect that you want. In addition, there is an effect that the selection operation of a transmission with four selection positions can be performed with a single cylinder device.
There are other effects that can be applied to a wide range of uses. Furthermore, in the movable range of the piston, where the force for displacing the piston rod is particularly small in relation to the pressure-receiving area, the inner diameter of the cylinder is partially increased, making it possible to prevent this reduction in the pressure-receiving area. The force for displacing the piston rod can be equalized, and as a result, there is no need to increase the dimensions of the piston rod and its related parts, and the effect of providing a compact and lightweight cylinder device is achieved.

[Brief explanation of drawings]

The drawings relate to embodiments of the present invention; FIG. 1 is a longitudinal cross-sectional view of a triple piston cylinder device showing the case where the piston rod is stopped at the rightmost first position, and FIG. Fig. 3 is a longitudinal sectional view showing the case where the piston rod is stopped at the middle third position, and Fig. 4 is a longitudinal sectional view showing the case where the piston rod is stopped at the leftmost fourth position. It is. 1 is a triple piston cylinder device, 2 is a cylinder, 2c is a hollow part of the cylinder, 3 is an outer piston, 3a is a hollow part of the outer piston, 3f is an end, 4 is an intermediate piston, 4a is a first intermediate piston, 4b is the second intermediate piston, 5 is the inner piston, 5a is the piston rod, D ₃ and D ₄ are the inner diameters of the cylinder, P ₁ is the first fluid port, P ₂ is the second fluid port, P ₃ is the third fluid port. This is the fluid port.

Claims (1)

[Scope of Claims] 1. A cylinder, which is slidably housed in the cylinder, one end is open, the other end is sealed with a wall, and the diameter of the end with the wall is smaller than that of the other parts. an intermediate piston consisting of a hollow outer piston formed larger than a diameter; a first intermediate piston and a second intermediate piston slidably housed within the outer piston; a stopper mounted on the inner circumferential surface of the outer piston so as to be located between the second intermediate piston and to limit the movement of the two intermediate pistons; an inner piston integrally formed with a piston rod passing through one end of the second intermediate piston and slidably passing through one end of the cylinder;
D ₀ is the diameter of the inner piston, D ₁ is the diameter of the intermediate piston, D ₂ is the diameter of the outer piston other than the end, and D ₄ is the diameter of the end of the outer piston _{. In the case of _} a first fluid port formed larger than the inner diameter and for displacing the outer piston to the piston rod side by a maximum amount; and a third fluid port for displacing the outer piston, the second intermediate piston, and the inner piston by a maximum amount toward the opposite side of the piston rod. and the piston rod can be set at four predetermined positions by the relative displacement of the outer piston, the intermediate piston, and the inner piston, and the interaction with the wall of the outer piston and the stopper. , and when the outer piston is displaced by the maximum amount to the opposite side of the piston rod, when the outer piston is displaced toward the piston rod, the pressing force is increased by increasing the pressure receiving area by increasing the diameter of the end portion. A triple piston cylinder device characterized in that it is configured to