JPH0133683B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a triple piston cylinder device, and particularly when the force for displacing the piston rod becomes small in relation to the pressure receiving area, the piston rod can be moved while equalizing the force for displacing the piston rod by applying a pressing force by an elastic body. the given 4
The present invention relates to a cylinder device that can be set at a point position with a simple configuration. In a conventional single piston cylinder device, the piston rod fixed to the piston can be reliably set at two points, but it is possible to set the piston rod at two points plus two intermediate positions, such as a transmission. The disadvantage is that it is not possible to reliably set the four points required for automatic gear shifting operations. Furthermore, Japanese Utility Model Application No. 55-1009 discloses a step for the purpose of positioning a rod in multiple stages, but this conventional example adopts a double piston type, and is suitable for vehicle transmissions. It is inferior in performance to perform very fine position control such as for speed change operation, and its structure, operation, and effect are different from the present invention. Furthermore, Japanese Patent Publication No. 47-50687 discloses a valve operating mechanism using a triple piston, but the conventional example has a limiter (corresponding to the "stopper 12" of the present application) fixed to the cylinder itself. However, the structure is different from the present invention. Also, Jitsukai Showa 53
-109594 discloses a stroke adjustment device for a multistage cylinder that uses two return springs to bias the pistons, but in this conventional example, each piston simply moves in one direction by the elastic force of the springs. The present invention merely discloses a configuration in which the pistons are brought back and returned, and does not include considerations such as using the return spring in consideration of the difference in force caused by the difference in the diameter of each piston. They have different purposes, configurations, and effects. 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 ensure that the piston rod can be set at four points with the configuration. Another object is to enable a single cylinder device to perform a selection operation for a transmission having four selection positions. A further object is to equalize the force for displacing the piston rod by adding the spring force of the compression spring when the force for displacing the piston rod is particularly small in relation to the pressure-receiving area. It is also an object of the present invention to provide a compact and lightweight cylinder device that eliminates the need to increase the dimensions of the piston rod and its related parts. In short, the present invention provides a cylinder, a hollow outer piston slidably housed within the cylinder, the hollow outer piston having one end open and the other end having a wall and being sealed; An intermediate piston consisting of a first intermediate piston and a second intermediate piston housed therein; and an intermediate piston located between the first intermediate piston and the second intermediate piston so as to limit the movement of these intermediate pistons. a stopper attached to the inner circumferential surface of the outer piston, and a piston rod slidably accommodated in the intermediate piston and passing through one end of the second intermediate piston and slidably passing through one end of the cylinder. an integrally formed inner piston, the diameter of the piston rod being
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.
In the case of D ₃ , the relationship D ₃ > D ₂ > D ₁ > D ₀ exists, and the outer piston accommodated in the hollow part of the cylinder is biased toward the piston rod to reduce the difference in diameter of each member. and a first fluid port for displacing the outer piston toward the piston rod by a maximum amount, the cylinder communicating with a hollow portion of the outer piston. a second fluid port for displacing the first intermediate piston a maximum amount within the outer piston toward the piston rod; and a second fluid port for displacing the first intermediate piston within the outer piston toward the piston rod; a third fluid port for providing a maximum amount of lateral displacement, the relative displacement of the outer piston, the intermediate piston, and the inner piston and interaction with the wall of the outer piston and the stopper The piston rod is configured to be able to be set at four predetermined positions, and the outer piston is displaced by applying a pressing force by the elastic body to the piston rod side when the piston rod is displaced by the maximum amount to the opposite side of the piston rod. It is characterized by the fact that 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, an inner piston 5, and a compressor that is an example of an elastic body. It is equipped with a spring 6. 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.
Further, the cylinder 2 communicates with a first fluid port _P1 for displacing the outer piston 3 by the maximum amount toward the piston rod 5a side, and a hollow portion 3a of the outer piston 3, so that the first intermediate piston 4a is connected to the outer piston 3.
A second fluid port _P2 for displacing the outer piston 3, the second intermediate piston 4b, and the inner piston 5 by the maximum amount toward the opposite side of the piston rod 5a. 3 fluid ports _P3 . 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 within 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 reason why the intermediate piston 4 is divided into two parts, the first intermediate piston 4a and the second intermediate piston 4b, is because the second intermediate piston 4b is fixed and the stroke l ₂ is obtained independently. It is possible,
Next, the first intermediate piston 4a is fixed so that the stroke l ₃ -l ₁ can be obtained independently. 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 set to Q ₄ . The compression spring 6 is arranged in the hollow part 2c of the cylinder 2, and its both ends are accommodated in recesses 2h and 3h formed in the left end 2g of the cylinder 2 and the wall part 3b of the outer piston 3, respectively. It's getting old. and by the compression spring the outer piston 3
is biased toward the piston rod 5a. The present invention is configured as described above, and its operation will be explained below. First, the case where the piston rod 5a is set to 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, when fluid is caused to flow into the second fluid port _P2 as shown by arrow _B2 , the fluid flows into the hollow portion 3a through the groove 3d and the communication hole 3e, and the first intermediate piston 4a is moved to the stopper 12. The inner piston 5, together with the second intermediate piston 4b, is displaced to the rightmost position where the wall portion 4f of the second piston hits 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 set at the first position _Q1 . Therefore, for example, by selecting this first position _Q1 , the transmission
It becomes possible to shift to 5th or 6th gear. Next, move the piston rod 5a to the intermediate second position Q ₂
The case where the setting is made 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, the cross-sectional area S ₁ of the hollow part 2c of the cylinder 2, the cross-sectional area of the piston rod 5a S ₂ , and the compression spring If the spring force of 6 is f, then the force F ₁ that presses the outer piston 3 in the right direction in the figure is F ₁ =
PS ₁ +f, 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 (S ₁ - _{S 2} )
= PS ₁ - PS ₂ , and the force F ₁ is larger than the force F ₂ by an amount corresponding to PS ₂ +f. 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
It is moved to the left by the amount of and is set to 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 of setting will be explained with reference to FIG.
While maintaining the state shown in Figure 2, open the second fluid port.
When the supply of fluid from P ₂ is stopped, the inner piston 5, together with the first intermediate piston 4a,
The wall 4c of the intermediate piston 4a is the outer piston 3.
It is displaced to the left within the range of stroke l ₂ until it hits the wall 3b of , 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 is set 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 fourth maximum 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 set 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 ,
Definitely set to 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 ,
Let the diameter D ₂ of the intermediate piston 4 be mD ₀ +nD ₀ and the diameter D ₃ of the outer piston 3 be mD ₀ +2nD ₀ (m and n
is a constant). and first, second and third fluid ports.
It is assumed that the pressures P of the fluids flowing into P ₁ , P ₂ , and P ₃ are all the same, and the spring force of the compression spring 6 is f. 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 ² ₀ P F ₂₃ = π/4 (m ² −1) D ² ₀ P F ₃₄ =π/4{(m+2n) ² −1}D ² ₀ P−f. 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/4D ² ₀ P+f F ₃₂ = π/4 {(m+n) ² −m ² +1}D ² ₀ P F ₂₁ =π/4m ² D ² ₀ P. In the above formula, for example, m=2, n=1 or m=
3, and by substituting n=1, it becomes as shown in Table 1.

[Table] As can be seen in Table 1, the coefficient of pressure P in the case of force F ₃₄ is 15 or 24, which is very large compared to other cases, whereas the coefficient of pressure P in case of force F ₄₃ is 0.25, which is very small compared to the other cases, but in this case, the spring force f of the compression spring 6 is added to increase the force _F43 . Further, the force F ₃₄ is reduced by the spring force f, but since the coefficient of the pressure P has become very large, the reduction in the spring force f has almost no effect and can be ignored. As described above, move the piston rod 5a to the fourth position Q ₄
When the force for displacing the piston rod 5a is particularly small, as in the case of displacing the piston rod from the piston rod _5a to the third position Q3, the spring force f is added by the compression spring 6 and increases, so that the force required to displace the piston rod 5a is increased. The forces of the piston rod 5a are equalized, especially the piston rod 5a.
There is no need to increase the diameter _D0 . 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. In the above embodiment, the elastic body 6 is described as a compression spring in the form of a coiled spring, but an air spring in the form of a bellows or a rubber material may be used instead of the compression spring. Alternatively, the end of the outer piston 3 on the piston rod 5a side may be pulled by a tension spring to bias the outer piston toward the piston rod 5a. Furthermore, in the above description, the fluid may be air or oil. Since the present invention is constructed 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 set at the four-point position with a simple construction. This has the effect that the selection operation of a transmission having four selection positions can be performed with a single cylinder device, and that it can be applied to a wide range of other uses. Furthermore, since the spring force of the compression spring is added when the force for displacing the piston rod is particularly small in relation to the pressure receiving area, the effect of equalizing the force for displacing the piston rod can be obtained. Further, as a result, there is no need to increase the dimensions of the piston rod and its related parts, and a compact and lightweight cylinder device can be provided, resulting in extremely excellent effects.

[Brief explanation of drawings]

The drawings relate to an embodiment of the present invention, and FIG. 1 is a longitudinal cross-sectional view of a triple piston cylinder device showing a case where the piston rod is set at the rightmost first position;
Fig. 2 is a longitudinal sectional view showing the case where the piston rod is set at the intermediate second position, Fig. 3 is a longitudinal sectional view showing the case where the piston rod is set at the intermediate third position, and Fig. 4 is a longitudinal sectional view showing the case where the piston rod is set at the intermediate third position. 4th leftmost
FIG. 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, 4 is an intermediate piston, 4a is a first intermediate piston, 4b is a second 5 is an inner piston, 5a is a piston rod, 6 is a compression spring which is an example of an elastic body,
P ₁ is the first fluid port, P ₂ is the second fluid port,
_P3 is the third fluid port.

Claims (1)

[Scope of Claims] 1. A cylinder, a hollow outer piston that is slidably housed in the cylinder and that is open at one end and sealed with a wall at the other end, and a hollow outer piston that is slidably housed within the outer piston. a first intermediate piston and a second freely housed intermediate piston;
and an intermediate piston mounted on the inner circumferential surface of the outer piston so as to be located between the first intermediate piston and the second intermediate piston and to restrict movement of both intermediate pistons. and an inner piston integrally formed with a piston rod that is slidably housed in the intermediate piston and passes through one end of the second intermediate piston and slidably passes through one end of the cylinder. , the diameter of the piston rod is D ₀ , the diameter of the inner piston is D ₁ , the diameter of the intermediate piston is
D ₂ , and when the diameter of the outer piston is D ₃ , there is a relationship of D ₃ > D ₂ > D ₁ > D ₀ , and the outer piston is accommodated in the hollow part of the cylinder and urges the outer piston toward the piston rod. and an elastic body for equalizing the force difference caused by the difference in diameter of each member, and the cylinder further includes a first fluid port for displacing the outer piston by a maximum amount toward the piston rod. a second fluid port communicating with the hollow portion of the outer piston for displacing the first intermediate piston by a maximum amount toward the piston rod within the outer piston; and a third fluid port for displacing the inner piston a maximum amount opposite the piston rod, the relative displacement of the outer piston, the intermediate piston, and the inner piston and the wall of the outer piston. and the piston rod can be set at four predetermined positions by interaction with the stopper, and a pressing force by the elastic body is applied to the outer piston toward the piston rod when the piston rod is displaced by the maximum amount to the opposite side of the piston rod. A triple piston cylinder device characterized in that it is configured to be displaced by adding.