DE3211232A1 - ENERGY-SAVING METHOD FOR OPERATING A PISTON-CYLINDER COMBINATION AND DEVICE FOR IMPLEMENTING THE METHOD - Google Patents

Description

description

The invention relates to a method and a device according to the preambles of claims 1 and 2, respectively.

The invention relates in particular to piston-cylinder combinations actuated by gas or compressed air, in particular to one energy-saving method and apparatus for use with such piston-cylinder combinations.

In these piston-cylinder combinations, the piston moves reciprocates in the cylinder and creates a first variable volume between a first end of the cylinder and a first end of the piston and between a second end of the cylinder and a second end of the piston have a second variable volume. In general, high gas or Air pressure is applied to the first variable volume while the second variable volume is evacuated to the atmosphere, thereby pushing the piston towards the second end. A rod is attached to the piston while the other end of the rod some type of consumer is attached so that the movement of the piston to the second end causes it against that consumer Work is being done. This movement is called the working stroke.

As a device for returning the piston to its starting position there is typically a spring between the second end of the piston and the second end of the Cylinder. When the high pressure is applied to the first variable volume and pushes the piston toward the second end, it also performs work against the spring, which is compressed, thereby storing energy in it. When the high pressure is removed from the first variable volume, generally by evacuating it to the atmosphere occurs, the spring uses the energy stored in it to return the piston to its original position. These

Spring requires that the working pressure medium is at a sufficiently high pressure, which is in addition to the workload overcomes the spring resistance. This results in the performance of a greater work with each working stroke than it is required by the workload alone.

Another typical working method is to apply high pressure alternately to the first and second ends of the cylinder exerted and the piston pushed back and forward. When the workload on the pole is essentially unidirectional acts, the cylinder and the piston absorb the force exerted by the high pressure pressure medium during the return stroke. This recording results in some additional cylinder degradation and waste of energy.

To return the piston, it has been proposed to use the same pressurized fluid that was used to push the piston is used on its working stroke. However, in order for such systems to work, the pressure medium at the second end must be on a larger piston area than act at the second end. For example, U.S. Patent 3,824,898, incorporated herein by reference, shows a valve-cylinder combination in tandem with two pistons in such a way that the initial work on one piston with a relatively small cross-sectional area is performed, while the restoring work on a relatively large one Cross-sectional area is made in that the two ends the cylinders are connected to each other in such a way that the same pressure is applied to both of them. Although both pistons are from the same pressure, since the force exerted on a surface is equal to pressure times the cross-sectional area, is the The force exerted on the larger piston is greater than the force exerted on the smaller piston, causing the piston to reset will.

This invention is not very practical by requiring that a special piston-cylinder device with two pistons

and cylinders together with the valve assembly for their actuation is used. This device can only work in one direction. The working fluid has to last of work press on the small piston, while the larger piston must be used for the return stroke.

The main object of the invention is to create an energy-saving Apparatus made with a conventional piston-cylinder combination including a single cylinder and a single piston can be used in such a way that the same pressure medium as used for the working stroke for the return stroke can be. Another object of the invention is to provide an energy saving device which will operate in this way can that the return stroke takes place by a pressure acting on the rod side of the piston, this side being a smaller one Cross-sectional area than the area used for the working stroke. Another object of the invention is to provide a force to reset the piston, the force when the piston approaches its reset position decreases, thereby reducing the deterioration of the cylinder.

According to the invention, these objects are achieved by the Objects of claims 1, 2 fes-w. 8th.

Advantageous further developments of the invention are the subject of the subclaims.

The invention thus creates an energy-saving device which, with a first controlled pressure, a second controlled Pressure and a piston-cylinder combination can be used may, in which the piston reciprocates in the cylinder and between a first end of the cylinder and a first End of the piston a first variable volume and between a second end of the cylinder and a second end of the Piston forms a second variable volume. The invention has lines that optionally have a pressure medium connection below

provides the variable volumes and controlled pressures such that that delivered by the first controlled pressure Pressure medium used to move the piston to one end for the working stroke and then used again on the return stroke.

In the following, exemplary embodiments of the invention are described with reference to the drawing. Show it:

1a, 1b and 1c are schematic representations of an embodiment

of the invention in different stages of operation when the first controlled pressure a The high pressure source and the second controlled pressure are a low pressure sink;

2a, 2b and 2c show a cross section of a further embodiment of the invention at different stages of operation;

Fig. 2d is a schematic representation of the pressures in

the two variable volumes of the cylinder during operation of the embodiment of Figures 2a, 2b and 2c;

3 shows a cross section of a further embodiment

form of invention;

4a, 4b and 4c show a schematic representation of a further one

Embodiment of the invention in various Operating levels.

Fig. 1a shows an embodiment of the invention with a cylinder 2 and a piston 3 arranged therein. A first End 4 of cylinder 2 and a first end 6 of piston 3 are on the left-hand side of the drawing. Between the first ends 4 and 6 are a first variable volume 8. On the right-hand side of FIG

a second end 1O of the cylinder 2 and a second end 12 of the piston 3. Between the second ends 10 and 12 there is a second variable volume 14 which is opposite to the first variable volume 8 is sealed so that between the first variable volume 8 and the second variable Volume 14 in cylinder 2 no pressure medium connection consists. At the second end 12 of the piston 3 is a rod 13 attached. The invention is also operable if the Rod 13 is attached to the first end 6 of the piston 3. the Rod 13 can be attached to a consumer, not shown, outside of the cylinder 2 and work on this consumer in that they move back and forth of the piston 3 moves back and forth in the cylinder.

Fig. 1a also shows a first controlled pressure 16, a second controlled pressure 18 and a container 20. In Fig. 1a the first controlled pressure 16 is a high pressure source, such as a pump, while the second controlled pressure 18 is a low pressure sink is. In most applications, the second controlled pressure 18 is an opening to the atmosphere. The container 20 is in pressure medium connection with the second variable volume 14. The container 20 is simply a volume in which itself Pressure medium can also accumulate when the piston 3 is extended as far as possible to the end 10. If within or outside the cylinder 2 stops are present, which the piston 3 always at least at a given distance from the end Hold 10, the free volume in the cylinder after the attacks serves as a container 20. The container 20 can be outside of the Cylinder 2 located separate volume, which is in pressure medium connection with the second variable volume 14 is (Fig. 1), or can include the volume of the lines that connect the pressure medium to the second variable volume 14 manufacture.

A line 22 is a first line that optionally provides a pressure fluid connection between the first controlled pressure 16 and the first variable volume 8.

Direction 24 is used to open and close the line 22. The lines in Fig. 1a can be pipes, hoses, closed Channels or anything through which pressure medium can flow. Device 24 can be anything that includes lines can open and close. If the conduit is a hose, the device can be a hose clamp. When the line is a pipe, the device can be any type of valve used to open and close the pipe.

Line 26 is a second line that optionally provides fluid communication between the first variable volume 8 and the second variable volume 14 produces. A device 28 is used to open and close the line 26. Line 30 is a third line that optionally provides fluid communication between the first variable Volume 8 and the second controlled pressure 18 produces. A device 32 is used to open and close the line 30. A line 34 is a fourth line, the optional establishes a fluid communication between the second variable volume 14 and the second controlled pressure 18. A device 36 is used to open and close the line 34. A device labeled X is shown in the drawing closed while a device labeled O is open. The devices 24, 28, 32 and 36 can be manually, be operated by an electronic control, by a pressure-dependent control or otherwise.

The apparatus of Figures 1a, 1b and 1c operates in the following way:

According to FIG. 1 a, the devices 24 and 36 are opened first and devices 32 and 28 closed. This releases the pressurized fluid from the first controlled pressure 16 flow through the line 22 into the first variable volume 8 and onto the surface 6 of the piston 3 work. Since the on the other side of the piston 3 on the second

End of 12 acting pressure lower than the pressure controlled by the first Pressure, an unbalanced force acts on the piston 3, which presses it towards the end 10. When the strength is great is enough to overcome the frictional forces, namely the consumer attached to the rod 13 or any other forces connected with the moving piston, the piston 3 is pressed in the direction of the arrow 38 to the end 10 and thereby performs the desired work function. This is the working stroke. The rod 13 may extend from the end 4 instead of the end 10, in which case the work by the return stroke instead of by extending the rod as in FIG. 1.

Next, according to FIG. 1b, the devices 24 and 36 closed and the device 28 opened while the device 32 remains closed. This allows spreading of the high pressure pressure medium supplied to the first variable volume through line 26 into the container and into the second variable volume 14, so that almost equilibrium pressure is reached. In this moment it is Pressure medium in the line 26 and in the container 20 and in the first and second variable volumes 8 and 14, respectively, almost to equilibrium pressure which is less than the pressure delivered by the first controlled pressure 16 and higher than the pressure at the second controlled pressure 18 is. This is the equilibrium step.

Next, according to FIG. 1c, the device 28 is closed and the device 32 is opened, while the devices 24 and 36 remain closed. Since the line 30 is open, the first variable volume 8 is in pressure medium connection with that supplied by the second pressure 18 controlled lower pressure, while the pressure medium in the first variable volume 8 escapes quickly to the lower pressure, see above that the pressure in the first variable volume 8 quickly reaches the low pressure at the second controlled pressure 18. There the second variable volume 14 is at equilibrium pressure,

that higher than that supplied by the second controlled pressure 18 If the pressure is low, the pressure acting on the end 12 of the piston 3 is higher than that acting on the end 6 of the piston 3 Pressure. If the force acting on the end 12 is sufficiently higher than the force acting on the end 6, the friction and to overcome the other forces present, the piston 3 is moved in the direction of arrow 40 to the end 4. this is the Return stroke.

As the piston 3 moves towards the end 4, the volume of the second variable volume 14 increases and expands Pressure medium in the container 20 to fill the increasing volume, so that the pressure acting on the end 12 gradually is decreased. Thus, the force pushing the piston 3 towards the end 4 is reduced when the piston 3 approaches the end 4 approaching. If the equilibrium pressure is not high enough and the amount of pressure medium in the container 20 is not large enough, the pressure can be reduced so that the piston 3 is not completely returned to its starting position. if but the equilibrium pressure is sufficiently high and the container 20 is sufficiently large, the piston 3 is in its starting position returned. The following example illustrates the theoretical relationship between pressures and volumes for the one shown in FIG. 1 illustrated invention.

It is assumed that the pressure controlled by the first 16 supplied pressure medium is an ideal gas and the ideal gas law is applied so that

where P is the absolute pressure and T is the absolute temperature.

It is now assumed that the processes are isothermal, where P ₁ V ₁ = P ₂ V ₂ .

The following are given: A "= cross-sectional area of end 6

A _R = cross-sectional area of end 12 P _1n = high pressure at first controlled pressure 16

V "= volume of the first variable volume 8 at the end of the working stroke

^P EX ^{= low} pressure delivered by the second controlled pressure 18

= Volume of the rod 13 within the cylinder at the end of the return stroke

V _n = volume of the container 20

P = pressure in the container 20 and in the first and second variable volumes 8 and 14, respectively at the end of the equilibrium step.

Pp = pressure in the second variable volume at the end of the return stroke.

The ideal gas law is used for the equilibrium step, whereby

PV before equilibrium = PV after equilibrium:

PV + PV = P TV + V 1 ^r IN H jEX R EQ ¹ HR ^j

The solution for the equilibrium pressure is:

^P IN ^V H * ^P EX ^V R ^P EQ - V _H * V _R

It is assumed that before the return stroke the volume of the second variable volume 14 is negligibly small. It is also assumed that at the end of the return stroke the volume of the second variable volume 14 is equal to V "- V _n ^ ₁ .

rl KUU

Since the pressure medium spreads in the container 20 and the new volume of the second variable volume 14 during the Return stroke fills, where PV before propagation = PV after propagation, the following applies:

^P EQ ^V R - V ^V H- ^V ROD ^{) + P} F ^V R " ^P F« V ^V B0D ⁺ V

The solution for P is

P V

P V-V +

H ROD V ₁₃

In this example it is assumed:

V "= 1.0 volume unit A" = 3 inches ² π η ~

V_, = 0.8 volume unit A ₀ = 2.5 inches P _1n = 114.7 psia

^P EX ^{= 14} ' ^{7 psia} V _n ^ r. = 0.2 volume unit

P V + P V ρ _ IN H EX R

-EQ V _H + V _R

- 114.7x1.0 + 14.7x0.8 1.0 + 0.8

= 70.2 psia

_P. = Vi

^FV H- ^V R0D ^{+ V} R

70.2x0.8 1.0-0.2 + 0.8

= 35.1 psia

The forces acting on the piston 3, which are only caused by the pressure medium pressures in the cylinder, have the following values:

Force (P.J due to the pressure on the piston during the working stroke: w

V = P Ά - W INHS P _EX A _R

= 114.7 psia 3 in ² - 14.7 psia 2.5 in ² = 307.4 lbs

The force (F _R ) due to the pressure on the piston at the beginning of the

Return stroke is:

^F R ^{= P} EQ ^A R ~ ^P EX ^A H

= 70.2 psia χ 2.5 in ² - 14.7 psia x 3 in ² = 131.4 lbs

The force (F ") due to the pressure on the piston at the end of the return i;

hubs is:

= 35.1 psia χ 2.5 in ² - 14.7 psia a 3 in ² = 43.6 lbs

The previous calculations were repeated, dissolving P and P as V changed. For this The following values were assumed for calculations:

P = 114.7 psia (100 psig delivery pressure) P "" = 14.7 psia (O psig, atmospheric pressure)

V "= 1.0 volume unit

Xl

ν _ΏΛιΓ . = 0.2 volume unit A _H = 3 inches A _R = 2.5 inches ²

The following table gives the theoretical results:

^V R ^P EQ ( psia) ^P F (p sia)

0.6 77.2 33.1

0.8 70.2 35.1

1.0 64.7 35.9

1.2 60.2 36.1

1.4 56.4 35.9

V ^bs , 4 F _R lbs F _F lbs 307 , 4 .148.9 38.6 307 , 4 131.4 43.6 307 / 4 117.6 45.6 307 , 4 106.4 46.2 307 96.9 45.6

2a, 2b, 2c show a further embodiment of the invention in the form of a group of valves and channels in a single housing 42. This group of valves and channels can cooperate with a first controlled pressure 16, which is a high pressure pressure medium supplied by a pump or the like, with a second controlled one Pressure 18, which is a low pressure, approximately atmospheric pressure, with a four-way valve 44 and with a piston-cylinder combination 3, 2 similar to the combination shown in FIGS.

Although the in FLg. 2a, 2b, 2c shown valves and lines are all in a single housing, the same Arrangement of valves and lines work in the same way if the valves are connected to one another by lines separate housings. The single housing 42 is because of the convenience and economy of The housing 42 consists of two parts 42a and 42b. A non-porous flexible part made of material 43 is arranged between these two parts. The parts 42a and 42b are then bolted together and clamp the material 43 in place. Parts of the material will be described in connection with the valves and membranes formed by the material 43.

As in Figures 1a, 1b and 1c, the container 20 is simply a Volume in which pressure medium can also accumulate when the piston 3 is extended to the end 10. Are located within or outside of the cylinder 2 stops that the piston 3 always at least at a given distance from Hold the end 10, then the free volume in the cylinder 2 can serve as a container 20 after the attacks. The container 20 can be a separate volume outside the cylinder 2, which is in pressure medium connection with a second variable volume 14 is, see Fig. 2a, 2b and 2c, or the container can comprise the actual volume of the lines that the pressure medium

Establish a connection with the second variable volume 14.

The four-way valve 44 has two positions. In his first position According to Fig. 2a, it connects the first controlled pressure with the channel 46 in the housing 42b and the second controlled pressure 18 with the channel 48 in the housing 42b. In his second Position according to FIG. 2b, it reverses the connections in such a way that the first controlled pressure 16 with the channel 48 and the second controlled pressure 18 with the channel 46 in communication. The four-way valve 44 'can move from one position to the other by hand, by an electromagnet, by using a hydraulically operated device or by other known means.

The channel 46 leads to a shuttle valve 50 which is in communication with three channels 46, 52 and 54. The shuttle valve has two positions. In the first position shown in Fig. 2a, it sets the channel 46 in pressure medium connection with the Channel 52, which is in fluid communication with the first variable Volume 8 stands. At the same time, the shuttle valve 50 blocks the pressure medium connection between the channel 54 and the Channels 52 and 46. The channels 52 and 46, together with the shuttle valve 50, thus form a line, which can optionally be a pressure medium connection between the first variable volume 8 and the first controlled pressure 16 can produce.

In this second position shown in Fig. 2b, the shuttle valve is set 50 the channel 52 in pressure medium pre-connection with the channel 54 and blocks the connection between the channels 52 and 46. The shuttle valve 50 is a portion of the material 43 that is partially cut away from the remainder of the material 43 so that that it forms a flap attached to the housing 42. The movement of the flap of the shuttle valve 50 is controlled by the relative pressures controlled in the channels in a manner to be described.

The channel 54 is connected to a check valve 56. The check valve 56 allows the pressure medium to flow from passage 54 to passage 58 on the other side of check valve 56, but does not allow flow of Pressure medium in the opposite direction. A biasing spring 60 holds the check valve 56 in its correct position within the channel 58. The channel 58 is in fluid communication with the second variable volume 14. If the shuttle valve 50 is in such a position that there is a pressure medium connection from the channel 52 to the channel 54 produces, and if the pressure medium in channel 54 has a higher pressure than the pressure medium in channel 58, so that it is at the check valve 56 can flow past, pressure medium can from the first variable volume 8 via the channels 52, 54 and 58 to the second variable volume 14 flow. Thus, the channels 52, 54 and 58 together with the shuttle valve 50 and the Check valve 56 is a conduit that optionally provides a pressure medium connection between the first and second variable Volume 8 or 14 can produce.

The channel 48 leads to a membrane 62 which is part of the material 43. The membrane 62 is attached to the housing 42 at its edges and can be responsive to the relative pressures surrounding them by moving toward the lower pressure. The line 48 is located on one side of the membrane 62, while the channel 58 and an opening are located on the other side 63 to the channel 64, which is in communication with the second controlled pressure. When the channel 48 is in pressure medium communication with the first controlled pressure, the membrane 62 is on the side adjacent to the channel 48 of a higher Pressure is applied and moves away from the side with the higher pressure, closes the opening 63 to the channel 64 and interrupts the pressure medium connection between the channel 58 and the channel 64.

When the channel 48 connects in pressurized communication with the second controlled pressure 18, the diaphragm 62 is of a

applied lower pressure on the side lying on the channel 48 and moves to channel 48 by moving away from opening 63 to channel 64, thereby establishing fluid communication between the channel 58 and the channel 64 is opened. When the membrane 62 moves away from the opening 63 to the channel 64, there is a pressure medium connection between the second variable volume 14, the channel 58, the channel 64 and the second controlled pressure 18. When the diaphragm 62 is to Opening 63 moves towards, it interrupts the pressure medium connection between the second variable volume 14 and the second controlled pressure 18. Thus, the channels 58 and 64 together with the membrane 62 form a line, which optionally is a pressure medium connection between the second variable volume 14 and the second controlled pressure 18.

In the channel 52, which is in fluid communication with the first variable Volume 18 is, there is an opening 66 to the channel 68, which is in pressure medium connection with the second controlled Pressure 18 is. A closure member 70, which is part of the valve 72, is located in the opening 66. The closure link 70 is attached to the bottom of a shaft 74 that is located in channel 52. The upper end of the shaft 74 is on one Membrane 76 attached, which has an upper side 78 and a lower side 80. The membrane 76 is another part of the material The lower side 80 of the membrane 76 adjoins the channel 52, while the upper side 78 of the membrane 76 adjoins the chamber 82, which is in pressure medium connection with the line 58 and the second variable volume 14 via a channel 83. A biasing spring 84 is attached to the top 78 of the diaphragm 76 and to the housing 42b. The pressure acts on the upper and Undersides 78, 80 of the membrane 76 and on the upper and lower sides. 86, 88 of the closure member 70. The membrane 76 is flexible and responsive to changes in pressure on these sides by opening the attached valve 72 and the closure member 70 moves to or from the opening 66. When the diaphragm 76 moves towards the opening 66, it depresses the

Shaft 74 to the opening 66, the shaft 74 in turn pushing the closure member 70 out of the opening 66, whereby the Pressure medium connection between the channel 52 and the channel 68 is opened. This means that the membrane opens the pressure medium connection between the first variable volume 8 and the second controlled pressure 18. Thus, the channels 52 and form 68 together with valve 72 a conduit which optionally provides a pressure medium connection between the first variable volume 8 and the second controlled pressure 18 can produce. When the forces acting on pages 78, 80, 86, 88 are so great, that they push the membrane 76 away from the opening 66, then the closure member 70 moves in a direction in which it seals the pressure medium connection through the opening 66.

Operation of the embodiment of the invention shown in Figure 2a takes place in the following way:

To initiate the working stroke, the four-way control valve is moved into its first position in such a way that high-pressure pressure medium flows into the channel 46. Since the pressure in channel 46 is higher than the pressure in channel 54, the shuttle valve 50 is lowered. presses, opens the channel 46 to the channel 52 and closes the channel 54. This sets the first controlled pressure 16 in pressure medium connection with the first variable volume 8.

At the same time, the four-way control valve 44 sets the second controlled one Pressure in pressure medium connection with channel 48. Since the pressure in channel 48 is lower than the pressure in channel 58 is when the piston 3 begins its movement to the end 10, the diaphragm 62 moves to the channel 48, whereby the pressure medium connection between the second variable volume 14 and the second controlled pressure 18 via channels 58 and 64 is opened. This arrangement allows the membrane 62 and its surrounding channels to function as a quick release valve for the second variable volume 14.

The valve 72 is in a closed position,

since the pressure in the chamber 82, which is about the same as the second controlled pressure 18 is substantially lower than the pressure in channel 52, which is about the same as the first controlled Pressure is. This pressure differential causes the diaphragm 76 to move upward and seal the closure member 70 at the opening 66, which is closed. Since the first variable volume 8 is in fluid communication with the higher Pressure of the first controlled pressure 16 is and the second variable volume 14 in fluid communication with the lower Pressure of the second controlled pressure 18 is the piston 3 is pressed towards the end 10 as in the working stroke of FIG. 1a .

To initiate the equilibrium step of Fig. 2b, the four-way control valve 44 is moved to its second position, in which the first controlled pressure 16 -in pressure medium connection with the channel 48 and the second controlled pressure 18 in pressure medium communication with channel 46 are set. Since the membrane 62 is now subjected to a higher pressure in the channel 48, it moves downwards and closes the opening 63. The pressure medium in the channels 46 and 54 is roughly at the same pressure, namely the pressure of the second controlled pressure 18. However, the pressure medium in the channel 52 is at a higher pressure approximately equal to the pressure of the first controlled pressure 16 and starts at high speed to flow past the shuttle valve 50 into the channel 46. This rapid movement of the pressure medium takes the edge of the shuttle valve 50 and allows the high pressure fluid in passage 52 to react on the underside of shuttle valve 50.

Once the high-pressure pressure medium acts on the underside of the shuttle valve 50, the pressure difference causes a movement of the shuttle valve 50 to the channel 46, whereby the channel 46 is opened and the channel 54 is closed. The one located in the channel 52 High pressure fluid then moves into channel 54, past check valve 56, into channel 58 and finally

into the container 20 and the second variable volume 14. This enables the pressure in the first variable volume 8, im Container 20 and in the second variable volume 14 an achievement of equilibrium as in the equilibrium step of Fig. 1b. The speed at which the pressure medium flows through a channel flows depends on its cross-sectional area. By reducing the cross-sectional area of the channel 58 where the Line 53 enters channel 58 (this reduced cross-sectional area is denoted by 58A, the pressure medium speed is increased at this point, which is a decrease the pressure head in the reduced duct cross-section 58A. This same reduced pressure is available via channel 53 with the Chamber 82 in connection. Thus, when the pressure medium from the chamber 8 via the reduced cross section 58A into the chamber flows, the pressure in 58A, 83 and the chamber 82 is opposite to the pressure acting on the underside of the diaphragm 76 in the channel decreased. Thus, with the reduced pressure on its upper side, the membrane 76 remains in its uppermost position and holds the closure member 70 against the opening 66, while pressure medium flows from 8 to 14 and during the pressure equalization process passes through the reduced cross-sectional channel 58A. For the best operation of the invention it is for printing in the Chamber 82 desires to reproduce the pressure in the second variable volume 14 so that the valve 72 does not open too soon, before equilibrium fluid flow reaches zero. An adjustable needle valve can be inserted into channel 83 to slow down the flow of pressure medium into the chamber 82 and to cause a pressure change in the chamber 82, to reflect the change in pressure in the second variable volume. When the pressure is out of balance and the When the equilibrium flow approaches zero, the pressure on surfaces 78, 80 and 86 is approximately equal to the equilibrium pressure. while the pressure on the surface 88 is lower than the equilibrium pressure, namely equal to the pressure on the second controlled Pressure 18. In a moment somewhere before equilibrium pressure is reached, depending on the relative magnitudes of surfaces 78, 80, 86 and 88, valve 72 will suddenly open

and allows the pressure medium in the channel 52 to flow into the second controlled pressure 18. The pressure medium starts from Channel 58 to channel 54 and channel 52 to flow. However, the valve 56 closes, the escape of the pressure medium do to prevent. The pressure medium in the second variable volume 14, in the container 20, in the channel 58, in the channel 83 and in the Chamber 82 thus remains at equilibrium pressure, while the pressure medium pressure in the first variable volume 8 and in the Channel 52 approaches the lower second controlled pressure. Because the pressure on the top 78 of the diaphragm 76 is at equilibrium pressure remains while the pressure on the underside 80 decreases, the valve 72 will continue to open as soon as it is opened only a small amount. The valve 72 also serves as a quick release valve and allows the pressure medium in the first variable volume, a rapid flow to the second controlled pressure 18 without flowing through long lines.

At this point in time the valves are in the positions shown in FIG. 2c and begin the return stroke. The first changeable Volume 8 is in fluid communication with the second controlled pressure 18, while the container 20 and the second variable volume 14 from a further pressure medium connection blocked off with any other volume. The end 6 of the piston 3 is now subjected to the second controlled pressure 18 applied, which is lower than that on the end 12 of the piston 3 acting equilibrium pressure is. When the force acting on the end 12 is sufficiently higher than that acting on the end 6 Strength is to overcome friction and other prevailing forces, So the piston 3 is moved to the end 4 as in the case of the return stroke of FIG. 1c. When piston 3 moves to end 4, the volume of the second variable volume 14 increases and the pressure medium spreads in the volume 14 and in the container 20 to fill the increasing volume, so that the Pressure acting at the end of 12 is gradually reduced. Thus becomes the force pushing the piston 3 towards the end 4 is reduced when

piston 3 approaches end 4. When the equilibrium pressure is not high enough and the amount of pressure medium in the container 20 is not large enough, the pressure can be reduced so that the piston 3 is not completely in its starting position is returned. But if the equilibrium pressure is high enough and the container 20 is large enough, the Piston returned to its original position. This will make the piston by reusing part of the pressurized standing pressure medium returned, initially to the Pushing the piston was used on the power stroke. When the four-way control valve 44 is returned to its first position is, another working stroke begins and the cycle shown in Fig. 2a, 2b and 2c can be repeated.

FIG. 2d shows a pressure curve from an actual test with the embodiment of FIGS. 2a, 2b and 2c. The for The cylinder used in the experiment was a Hanna cylinder with a stroke of 310 mm and a diameter of 50.8 mm. Of the Bar diameter was 19 mm. The pressure in the first controlled pressure 16 was 84 psig (98.7 psia). The second controlled Pressure 18 was 0 psig (14.7 psia). The pressure readings were taken in the first variable volume 8 and in the second variable volume 14 during the working stroke, the equilibrium and the return stroke. The pressure readings indicate that when the four-way control valve 44 moves into its first Position for the working stroke at time t. the pressure in the first variable volume 8 increases rapidly. At the same time t. the pressure in the second variable volume 14 shows no change. This means static friction in the cylinder, with a Pressure of about 42 psig in the first volume 8 for the start of movement of the piston 3 is necessary. As soon as the piston 3 closes begins to move, the pressure in the first variable volume 8 suddenly drops with a corresponding sudden Pressure increase in the second variable volume 14 when the pressure medium in the second variable volume 14 by the moving piston 3 is compressed faster than

-lies to the second controlled pressure 18 can escape. The rapid succession of pressure peaks in the first and second variable volume 8 and 14 means a somewhat jerky movement of the piston 3, whereby the pressure medium in the first variable volume 8 has to overcome small amounts of static friction in order to move the piston 3 to the end 10 of the cylinder 2 to move. Stiction refers to friction that results in a stick-slip phenomenon, generally caused by a lack of lubrication between the seals and the surfaces they rub against. This type of static friction is typical in most cylinders. When using a piston seal designed as a rolling diaphragm, this type of static friction does not occur.

The working stroke is finished at time t ". The pressure in the first variable volume 8 is 84 psig and the second variable volume 14 0 psig. In a moment shortly before time t_ the four-way control valve 44 is moved into its second position. The pressure readings mean that the equilibrium step is taking place with the pressure in the first variable volume 8 decreasing while the pressure in the second variable volume 14 increases. At time t ₃ , the equilibrium step ends, the pressure in the first variable volume 8 being equal to 44 psig while the pressure in the second variable volume being equal to 36 psig. At time t., The return stroke begins, the pressure in the first variable volume 8 falling rapidly when the pressure medium escapes to the atmosphere. The pressure in the second variable volume 14 gradually decreases, the pressure medium spreading and filling the increasing volume that is created when the piston 3 moves back to the end 4 of the cylinder 2 on its return stroke.

Fig. 3 shows a further embodiment of the invention, the is similar to the embodiment of FIG. The differences between the embodiments of Figs. 2 and 3 relate to this valve used to open and close the line from the second variable volume 14 to the second controlled pressure 18. In Fig. 2 the valve contains the pressure controlled membrane

In FIG. 3 the valve is formed by a valve member 90. The valve member 90 is on the shuttle valve by means of a shaft 82 50 fastened in such a way that with an upward movement of the shuttle valve 50, the channel 46 is removed from the pressure medium connection with the channel 52 and to open the channel 54, causes an upward movement of the shaft 92, whereby the Valve member 90 is moved so that it seals the opening 63 and the pressure medium connection between the second variable Volume 14 and the second controlled pressure 18 interrupts. When the shuttle valve 50 moves down to close the channel 54 and to open the channel 46, it causes a downward movement of the valve member 90 and a pressure medium connection through the opening 63.

Since the closure member 90 is controlled by the movement of the shuttle valve 50 instead of the pressures around the valve member 90 it needs neither the channel 48 nor the alternating connection with the first and second controlled pressures 16, 18 as required in FIG. 3. This means that the four-way control valve 44 is replaced by a three-way control valve 94 which is in communication with the first and second controlled pressures 16, 18 and with the channel 46.

In Fig. 3, the check valve 56 is attached over the shaft 92, however, moves independently of the movement of the shaft. The shuttle valve 50 in Fig. 3 is structurally something distinguished from the shuttle valve 50 in FIGS. 2a, 2b and 2c. In Fig. 3, the shuttle valve 50 is not a flexible flap Material, but instead a stiffer link. The increased rigidity is for the shuttle valve 50 for actuating the Shaft 92 required, which controls the valve member 90. The shuttle valve 50 in FIG. 3 is also not attached to the housing 42. This is not necessary in FIG. 3, since it is sufficient to fasten the shuttle valve 50 to the shaft 92 in order to keep it in place to keep. A guide 91 on the shaft 92 restricts movement

of the shuttle valve 50 to mainly an axiala movement with a very little perpendicular movement to the shaft 92.

Another difference between Fig. 2 and 3 is that that the channel 64 communicates with the channel 68 communicating with the second controlled pressure 18, instead of a direct pressure medium connection between the Channel 64 and the second controlled pressure 18 to have. This enables a reduction of one connection on the housing 42, thereby reducing complexity and cost. The operation of the embodiment of the invention of FIG. 3 is shown in FIG essentially the same as FIG. 2 with the same lines open at the same times. The basic difference in Operation consists in that the valve member 90 is controlled by the shuttle valve 50 instead of by pressure medium pressure.

4a, 4b and 4c show a different embodiment of the invention in which two conventional valves, such as slide valves, are in fluid communication with the first and second controlled pressures 16, 18 and the first and second variable Volume 8, 14 are available and provide the same lines and provide the same sequence of opening and closing the pressure medium connection as in the previous figures. With this arrangement, however, the movement of the valves becomes time-dependent rather than pressure-dependent as in FIGS. 2 and 3 Control controlled. A two-way valve 100 has two positions. In its first position it sets the first controlled one Pressure 16 in pressure medium connection with a line 101 which is in connection with a five-way valve 102. In its second position it blocks the pressure medium connection between the line 101 and the first controlled pressure. That Five-way valve 102 has three positions. In his in Fig. 4a first position shown, it sets the line 101 in pressure medium connection with the first variable volume 8 and sets the second variable volume 14 in fluid communication with the second controlled pressure 18. In its second position

According to FIG. 4b, the five-way valve 102 sets the first variable Volume 8 in pressure medium connection with the second variable volume 14. In its third position of FIG. 4c The five-way valve 102 places the first variable volume 8 in fluid communication with the second controlled pressure 18 and blocks the connection with the second variable volume men 14.

The valves 100 and 101 are operated by one or more electromagnets or other control devices controlled which receive a signal as a function of the time lapse. The valves 100, 102 move together in such a way that valve 100 is first in its first position and valve 102 in its first position. Next, valve 100 is in its second position and valve 102 is in its second position. Finally, the valve 100 is in its second position and the valve 102 in its third Position. This embodiment has the same order of pressure medium connection as the other embodiments.

While these figures show a horizontal cylinder and valves moving in a vertical plane, is operating the invention with any orientation of cylinders and valves.

Claims (8)

3211231 BEETZ & PARTNER 667-33.5o6P (33.5o7H) March 26, 1982 Steinsdorfstrasse 1.0.8000 Munich 22 REXNORD INC. Milwaukee, Wisconsin 532ol V.St.A. Energy-saving process for actuating a piston-cylinder combination and device for performing the Procedure Expectations Energy-saving method of actuating a piston-cylinder combination, in which the piston reciprocates in the cylinder and a first variable volume between a first end of the cylinder and a first end of the piston and a second variable volume between a second end of the cylinder and the forms the second end of the piston,
marked - by setting the first variable volume in pressure medium connection with a first controlled pressure and of the second variable volume at a lower second controlled pressure to produce a pressure differential between the first and second variable volumes and moving the piston to the end with the lower one Pressure, - By interrupting the pressure medium connection between the second variable volume and the second controlled Pressure, removing the first variable volume from 667-CR1478-X-1)
(R1479-X-1) the pressure medium connection with the first controlled pressure and in pressure medium connection setting the first variable pressure with the second variable volume such that in the first and second variable Volume is almost reached equilibrium pressure, and - by interrupting the pressure medium connection between the first and the second variable volume and in pressure medium connection setting the first variable Volume with the second controlled pressure such that the pressure in the first variable volume corresponds to the second controlled pressure and the pressure difference between the first and the second volume reaches the piston resets. 2. Energy saving device for use with a first controlled pressure and a lower second controlled pressure as well as with a piston-cylinder combination in which Piston reciprocates in the cylinder and a first variable volume between a first end of the cylinder and a first end of the piston and a second variable volume between a second end of the cylinder and a second end of the piston generated - By a first line (22), which optionally has a pressure medium connection between the first variable volume (8) and the first controlled pressure (16), - Through a second line (26), which optionally has a pressure medium connection between the first variable volume (8) and the second variable volume (14) manufactures, - Through a third line (30), which is optionally a pressure medium connection establishes between the first variable volume (8) and the second controlled pressure (18), - Through a fourth line (34) which selectively has a pressure medium connection establishes between the second variable volume (14) and the second controlled pressure (18), and - By a control device which controls which of the lines (22, 26, 30, 34) are open to the pressure medium connection and which of the lines (22, 26, 30, 34) is closed, wherein the control device comprises a device (24; 28; 32; 36) which first opens the first and fourth lines (22; 34) and the second and third Line (26; 30) closes, next the first, third and fourth line (22; 30; 34) closes and the second Line (26) opens and finally the first, second and fourth lines (22; 26; 34) closes and the third Line (30) opens, whereby the pressure medium delivered by the first controlled pressure (16) pushes the piston (3) into moved a working stroke and part of the pressure medium is later reused to the piston (3) in one To move the return stroke (e.g. Fig. 1a-1c). 3. Device according to claim 2,
marked - By a shuttle valve (50) located in the first line (46), which selectively opens the first line (46) and closes, - by a check valve located in the second line (54) (56), which variable a pressure medium flow in only one direction between the first and the second Volume (8; 14) allows, - by a valve located in the third line (68) (72), which optionally opens and closes the third line (68), and - by a valve located in the fourth line (58) (62, 63), which optionally opens and closes the fourth line (58) (Fig. 2a-2c). -A- 4. Apparatus according to claim 3,
characterized, - That the first and the second line (46; 54) are in such a way cut that the shuttle valve (50) is in the first and the second line (46; 54), wherein the shuttle valve (50) changes its position as a function of pressure changes and optionally opens the first line (46) and the second line (54) closes and then the first line (46) closes and the second line (54) opens (Fig. 2a-2c). 5. Apparatus according to claim 4,
characterized, - That the valve (72) of the third line (58) has: - a main chamber in which the first, second and cut third line (46; 54; 68), - A shaft (74) located in the main chamber and having an upper and a lower end; - An opening (66) located in the main chamber, which leads to a line for a pressure medium connection with the second controlled pressure (18) leads, - A closure member (70) fastened to the lower end of the shaft (74) and located in the opening (66), which closes the opening (66) when the shaft (74) moves away from the opening (66), and a pressure medium connection through the opening (66) when the shaft (74) moves towards the opening (66), and -one. Membrane (76) with upper and lower sides (78, 80), the lower side (80) adjoining the main chamber (52) and the upper side (78) adjoining the second chamber (82), which is in pressure medium connection with a line (83) connected to the second variable volume (14) can be brought into pressure medium connection, the membrane (76) being attached to the upper end of the shaft (74) in this way is that movement of the membrane (78) towards the opening (66) causes the closure member (70) to move and the pressure medium connection opens through the opening (66) (Figures 2a-2c). 6. Apparatus according to claim 5,
characterized, - That the valve (62, 63) located in the fourth line (58) is pressure-controlled (FIGS. 2a-2c). 7. Apparatus according to claim 5,
characterized, - That the valve (62, 63) located in the fourth line (58) by a shaft (92) on the shuttle valve (50) in such a way is attached that when the shuttle valve (50) opens the first line (46) and the second line (54) closes, it also causes the valve (63) of the fourth line (58) to open this line, and if that Shuttle valve (50) closes the first line (46) and opens the second line (54), it also causes the Valve (63) of the fourth line (58) closes this line (Fig. 3). 8. Energy saving device for use with a first controlled pressure and a lower second controlled Pressure as well as with a piston-cylinder combination, in which the piston moves back and forth in the cylinder and a first variable volume between a first end of the cylinder and a first end of the piston and a second variable Volume generated between a second end of the cylinder and a second end of the piston, marked - Through a first line (22), which optionally has a pressure medium connection establishes between the first variable volume (8) and the first controlled pressure (16), - Through a second line (26), which optionally has a pressure medium connection between the first changeable lumen (8) and the second variable volume (14) produces, - Through a third line (30), which is optionally a pressure medium connection establishes between the first variable volume (8) and the second controlled pressure (18), - Through a fourth line (34) which selectively has a pressure medium connection between the second variable volume (14) and the second controlled pressure (18), and - By a time-dependent control device which controls which of the lines (22, 26, 30, 34) is open to the pressure medium connection and which of the lines (22, 26, 30, 34) is closed and the first the first and fourth lines (22; 34) opens and the second and third line (26; 30) closes, next the first, third and fourth Line (22; 30; 34) closes and the second line (26) opens, and finally the first, second and fourth lines (22; 26; 34) closes and the third line (30) opens, whereby the pressure supplied by the first controlled pressure (16) Pressure medium moves the piston (3) in one working stroke and is recirculated for use in a return stroke (e.g. Figs. 1a-1c). Device according to claim 8,
characterized, - That the first, second, third and fourth lines (22; 26; 30; 34) have conventional slide valves and - That the time-dependent control device controls the position of the slide valves.