JPH04302724A - Spring installing length regulating mechanism - Google Patents

Abstract

PURPOSE:To convert the length of instilling a spring freely by opening and closing valves to suck and exhaust the oil in oil chambers into a casing, and thereby expanding and contracting a bellows to increase and decrease the pressing force of a spring to a piston. CONSTITUTION:Inside a casing 1, a piston 2 to reciprocate in a specific scope, a spring 3 to hold the piston 2, and a bellows 5 unitary with a valve seat to hold the spring 3 are provided respectively. And the inside of the bellows 5 is connected to a low pressure oil chamber 8a and a high pressure oil chamber 8b respectively through pipes 6 and plural valves 7a and 7b set at the outside of the casing 1. As a result, when one side valve 7b, for example, is opened, the oil flows in the bellows 5 from the high pressure oil chamber 8b to expand the bellows 5, and thereby, the pressing force is increased to the piston 2 through the spring 3. Consequently, by regulating the oil capacity in the bellows 5, the optimum spring reaction can be set constantly.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to a spring attachment length adjustment mechanism for adjusting the attachment length of springs used in various industrial equipment, etc., and in particular to a spring attachment length adjustment mechanism for adjusting the attachment length of springs used in various industrial equipment. The present invention relates to a spring attachment length adjustment mechanism suitable for automatically adjusting the attachment length of a spring for use.

0002

2. Description of the Related Art As is well known, the piston of a free piston type Stirling engine operates based on the balance of forces such as the pressure of gas sealed in the cylinder, the pressure applied to the piston, and the reaction force of a spring. Incidentally, in such a free piston type Stirling engine, the operating state may change due to changes in discharge pressure or the like during engine operation, which may cause the balance of forces applied to the piston to collapse. In such a case, it is necessary to adjust the spring reaction force and the sealing pressure in order to restore the balance to the correct state. However, in order to adjust the spring reaction force, it was necessary to change the spring installation length, and this required disassembly of the engine, so it was practically impossible to adjust the spring reaction force while the engine was running. As a result, until now, the operating conditions of the Stirling engine were determined by the length of the spring attachment, and the engine had to operate only under very narrow conditions. In other words, since the spring mounting length cannot be adjusted externally, the range of engine operating conditions is extremely narrow.

[0003]For this reason, recently, in order to eliminate the above-mentioned inconvenience, in order to make it possible to adjust the mounting length of the spring, the mounting length has been adjusted using a screw as shown in Fig. 3. have been proposed. The mechanism for adjusting the spring attachment length using this screw will be explained with reference to FIG. 3. In FIG. 3, 1 is a casing, 2 is a piston, 3 is a spring, 9 is a stator,
10 is a spring adjuster, and the reaction force of the spring 3 acting on the piston 2 is controlled by rotating the spring adjuster 10 to adjust the amount by which the spring adjuster 10 protrudes into the casing.

0004

However, the adjustment by the above method has the following problems. First of all, it is necessary to secure a space behind the head of the spring adjuster to manually turn the spring adjuster from the outside, and this imposes restrictions on the arrangement of each member when designing the device. This means that it is actually difficult to incorporate this device into the center of the device, where there is little free space. Next, when trying to adjust the screw type spring adjuster mentioned above by automatic control,
A high torque motor or speed reducer is required to rotate the spring adjuster, which requires a large amount of space. Furthermore, if it is difficult to place them near the spring adjuster, transmission devices such as gears and shafts will be required, making the mechanism complicated. Finally, when attempting to adjust the spring reaction force, it is generally necessary to measure the spring reaction force, but it may be difficult to measure the spring reaction force using any of the above methods. That is,
In order to measure the spring reaction force, it is necessary to place a sensor inside the casing, which is especially difficult under unusual conditions such as when the inside of the casing is under high pressure or filled with oil. There may be cases where there are no sensors that can be used in such an atmosphere. When attempting to adjust the spring attachment length as described above, there are problems such as various design limitations and difficulty in measuring the spring reaction force.

Therefore, in the present invention, a bellows is attached to one end of the spring, and by adjusting the amount of oil in the bellows from the outside, the length of the spring attachment can be freely changed, thereby solving the above problem and improving engine operation. This is an attempt to expand the range of conditions.

[0006]

[Means for Solving the Problems] Therefore, the present invention provides a spring attachment length adjustment mechanism that includes a piston that is housed in a sealed casing and reciprocates within a certain range within the casing, and a spring that supports the piston. and a bellows that is integrated with a valve seat that supports the spring, and the bellows is configured such that the height of the bellows can be changed by supplying and discharging liquid into the bellows, and the height of the bellows is adjustable. is determined by the oil capacity in the bellows, and the bellows internal pressure is determined based on the casing internal pressure and the spring reaction force. It is a means.

[0007]

[Operation] When the valve 7b is opened and oil flows into the bellows from the high-pressure oil chamber 8b, the oil capacity inside the bellows 5 increases and the length of the bellows 5 is extended.Conversely, the valve 7a is opened and the oil inside the bellows is discharged. Then, the length of the bellows 5 is reduced. In response to such movement of the bellows, the pressure outside the bellows 5, that is, inside the casing 1, and the pressure of the liquid inside the bellows 5 are measured, and the reaction force of the spring 3 is calculated based on this. based on,
By adjusting the oil capacity in the bellows 5, the optimum spring reaction force is always set.

[0008]

[Example] Hereinafter, embodiments of the present invention will be explained based on the drawings. Fig. 1 is a configuration diagram of the spring attachment length adjustment mechanism of this embodiment, and Fig. 2 explains the spring attachment length adjustment of this embodiment. FIG. As shown in Fig. 1, this spring attachment length adjustment mechanism includes a piston 2 that reciprocates within a certain range within a casing, a spring 3 that presses the piston 2, and a bellows 5 that is integrated with the valve seat that supports the spring 3. These are housed in a sealed casing 1. Inside the bellows 5 are pipes 6 and valves 7a arranged outside the casing.
, and are connected to a low pressure oil chamber 8a and a high pressure oil chamber 8b via valves 7b, and the bellows 5, piping 6, and each oil chamber 8a, 8b are filled with oil.

Therefore, when the valve 7b is opened, oil flows into the bellows 5 from the high pressure oil chamber 8b, and the bellows 5
The internal oil capacity increases, the length of the bellows 5 increases, and the pressing force toward the piston 2 via the spring 3 increases. Conversely, by opening the valve 7a, the length of the bellows 5 is reduced, and the pressing force toward the piston 2 via the spring 3 is reduced. Note that these valves 7a
, 7b are replaced with solenoid valves and operated by a control device, automatic control becomes possible. In addition, in order to measure the spring reaction force, a pressure sensor 4a is installed in the casing 1, and a pressure sensor 4b is installed in the piping 6, so that the pressure inside the casing 1 and the inside of the bellows 5 can be measured. There is.

Since the spring attachment length adjusting mechanism according to the above embodiment is constructed as described above, it operates as follows. That is, since the inside of the bellows 5 and the inside of the pipe 6 are filled with oil, which is an incompressible liquid, the length of the bellows 5 is uniquely determined by the capacity of the oil inside them, and the reaction force of the spring 3, etc. It is thought that there will be no change due to Therefore, when the valve 7b is opened and oil flows into the bellows from the high-pressure oil chamber 8b, the oil capacity inside the bellows 5 increases and the length of the bellows 5 increases. Conversely, when the valve 7a is opened and the oil inside the bellows is discharged, the length of the bellows 5 is reduced.

As described above, the bellows 5 expands and contracts up and down depending on the amount of oil inside the bellows, and at the same time, the gas pressure acting on the outside of the bellows 5 (gas pressure inside the casing) is transmitted to the oil pressure inside the bellows. At the same time, since the spring 3 presses the upper part of the bellows 5, this force increases the pressure of the oil inside the bellows 5. From this, the outside of the bellows 5, that is, the casing 1
By measuring the internal pressure and the pressure of the liquid inside the bellows 5, the reaction force of the spring 3 can be measured, and by adjusting the oil capacity inside the bellows 5 based on this, the optimum spring reaction force can always be obtained. Can be set.

The principle of measuring the bellows reaction force and spring attachment length will be explained in detail below with reference to FIG. In the figure, Xa represents the length from the bottom of the piston to the bottom of the bellows at the top dead center of the piston, and Xp, Xs, and Xb represent the position from the top dead center of the piston, the length of the spring, and the length of the bellows, respectively. Further, Sb represents the effective cross-sectional area of the bellows, Pb represents the internal pressure of the bellows, and Pe represents the internal pressure of the casing. And Xfs is the spring free length, Xfb
is the free length of the bellows, and Ks and Kb are the spring constant and the bellows spring constant, respectively. As mentioned above, the bellows length Xb is determined by the amount of oil inside the bellows, and is not affected by the piston position Xp.

In FIG. 2, the balance equation of the force at the top of the bellows is

[Equation 1] (Xfb-Xb)×Kb +Pb×Sb =
It is expressed as (Xfs-Xs)×Ks +Pe×Sb. Also, as is clear from Figure 2, Xa, Xp, Xb, and Xs are

[Math 2] Xa=Xp+Xb+Xs It is expressed as

First, when the internal pressure of the bellows becomes the minimum, that is, when the force applied to the upper part of the bellows becomes the minimum and the piston reaches the top dead center, the piston position Xp is

[Math 3]X
p=0. From this,

[Formula 4] Xs=Xa-Xb holds true. Substituting this into number 1

[Equation 5] (Xfb-Xb)×Kb +Pb×Sb = [Xfs
− (Xa −Xb)]×Ks +Pe×Sb. Therefore, the above number 5 is

[Formula 6] It is expressed as Xb=A+B×(Pb-Pe). here

[Formula 7] A=(Xfb×Kb −Xfs×Ks +Xa
×Ks)/(Kb +Ks)

[Formula 8] B=Sb/(K
b+Ks). Further, the spring attachment length is expressed as Xs when the piston is at the top dead center. Therefore, the spring installation length Xss is

[Equation 9]Xss=Xs So, from numbers 1 and 4,

[Equation 10] Xss=Xa−[A+B×(Pb−Pe)]. By measuring the bellows internal pressure and the casing internal pressure at the time when the bellows internal pressure becomes minimum in this way,
The bellows length Xb and the spring attachment length Xss can be determined.

Next, when the piston is at an arbitrary position Xp,
The spring reaction force Fs is determined as follows. That is, the spring reaction force Fs is

[Equation 11] It is expressed as Fs=(Xfs-Xs)×Ks, and when this is substituted into Equation 1, we get

[Formula 12] (Xfb-Xb)×Kb+Pb×Sb=Fs+
It becomes Pe×Sb. Therefore, the spring reaction force Fs is

[Formula 13] Fs=(Pb-Pe)×Sb+(Xfb-Xb)×Kb
So, by substituting the number 6 into this, we get

[Formula 14] Fs=(Pb − Pe)×Sb + [Xfb−
[A+B×(Pb −Pe)]]×Kb. Therefore, the spring reaction force Fs is expressed by the following equation.

[Formula 15] Fs=C×(Pb-Pe)+D where C, D
teeth

[Formula 16] C=Sb×Ks/(Kb+Ks)

[Formula 17] D=Kb×Ks×(Xfb+Xfs−Xa)/(Kb+
Ks). The variables constituting these variables A, B, C, and D are known constant values. Therefore, the spring reaction force Fs can be determined by measuring Pb and Pe.

The piston position Xp can also be determined by measuring the pressure inside the casing and the bellows. First, the spring installation load Fss is determined from the spring installation length Xss using the following equation.

[Formula 18]Fss=(Xfs-Xss)×KsThis Fs
It can be said that s is the spring reaction force when the piston is at the top dead center. If the piston is at an arbitrary position Xp and the spring reaction force at that time is Fs, then
The reaction force difference dFs is caused by the spring being compressed by Xp,

[Formula 19] dFs=Xp×Ks It is expressed as Also

[Formula 20] dFs=Fs-Fss It is. Therefore, the following equation holds.

[Formula 21] Xp×Ks=Fs−Fss From this, the piston displacement Xp is

[Equation 22] It can be obtained from Xp=(Fs-Fss)/Ks. By measuring the pressure inside the casing and bellows in this way, the spring installation length, spring reaction force, and piston position can be determined.
This makes it possible to obtain an optimal balance of forces applied to the piston.

[0017]

[Effects of the Invention] As detailed above, by adjusting the spring attachment length using the method of the present invention,
This enables real-time measurement of spring reaction forces, which allows for the optimal balance of forces applied to the piston. Furthermore, as long as oil piping can be introduced, the spring attachment length adjustment mechanism according to the present invention can be used in any location, increasing the degree of freedom in equipment design. Also, when performing automatic control,
As long as an oil pressure source is available, the spring installation length adjustment mechanism can be automated by simply changing the valves 7a and 7b to solenoid valves.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of a spring attachment length adjustment mechanism of this embodiment.

FIG. 2 is an explanatory diagram for explaining adjustment of the spring attachment length in this embodiment.

FIG. 3 is a diagram of a conventional spring attachment length adjustment mechanism.

[Explanation of symbols]

1 Casing 2 Piston 3 Spring 4a Pressure sensor 4b Pressure sensor 5 Bellows 6 Piping 7a Valve 7b Valve 8a Low pressure oil chamber 8b High pressure oil chamber

Claims (1)

[Claims] [Claim 1] Housed in a sealed casing,
a piston that reciprocates within a casing within a certain range;
It has a spring that supports the piston, and a bellows that is integrated with a valve seat that supports the spring, and the bellows is configured so that the height of the bellows can be changed by supplying and discharging liquid into the bellows. and the bellows height is determined by an oil capacity in the bellows, and the bellows internal pressure is determined based on the casing internal pressure and the spring reaction force. length adjustment mechanism