GB2125905A - Fluid actuator for shower assemblies - Google Patents

Fluid actuator for shower assemblies Download PDF

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Publication number
GB2125905A
GB2125905A GB08223371A GB8223371A GB2125905A GB 2125905 A GB2125905 A GB 2125905A GB 08223371 A GB08223371 A GB 08223371A GB 8223371 A GB8223371 A GB 8223371A GB 2125905 A GB2125905 A GB 2125905A
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GB
United Kingdom
Prior art keywords
piston
chamber
valve
exhaust
switch
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
GB08223371A
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GB2125905B (en
Inventor
Hans Friedrich Silva Reiss
Martin Donald Waters
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Reiss Engineering Co Ltd
Original Assignee
Reiss Engineering Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Reiss Engineering Co Ltd filed Critical Reiss Engineering Co Ltd
Priority to GB08223371A priority Critical patent/GB2125905B/en
Publication of GB2125905A publication Critical patent/GB2125905A/en
Application granted granted Critical
Publication of GB2125905B publication Critical patent/GB2125905B/en
Expired legal-status Critical Current

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F03—MACHINES OR ENGINES FOR LIQUIDS; WIND, SPRING, OR WEIGHT MOTORS; PRODUCING MECHANICAL POWER OR A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR
    • F03C—POSITIVE-DISPLACEMENT ENGINES DRIVEN BY LIQUIDS
    • F03C1/00—Reciprocating-piston liquid engines
    • F03C1/08—Distributing valve-gear peculiar thereto
    • F03C1/10—Distributing valve-gear peculiar thereto actuated by piston or piston-rod

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Nozzles (AREA)

Abstract

Means for controlling reciprocation of the shower pipe of a shower assembly for use inter alia in the paper and board manufacturing industries, comprises a cylinder 1 and piston 2 which separates the cylinder into two chambers 4, 5; a rod 3 is connected to the piston 2 extends through the chamber 5 and is adapted for connection to the shower pipe for reciprocation thereof. The chambers 4, 5 are connected to a source of pressurized fluid and exhaust via throttle means by a two-position valve 6 controlled by proximity switches P1, P2, which sense the presence of the piston in its limit positions. To reduce the dwell time when the chamber 5 is initially connected to the source of pressurized fluid, the chamber 4 is temporarily connected via an auxiliary valve 8 to exhaust, the connection being broken as soon as the piston starts to move. <IMAGE>

Description

SPECIFICATION Improvements in and relating to shower assemblies The present invention relates to improvements in shower assemblies particularly but not exclusively for use in the paper and board manufacturing industries.
Such a shower assembly comprises an elongated tubular member having a plurality of spray outlet means spaced apart along its length.
In use the assembly is reciprocated axially generally using a double acting cylinder and piston, the rod of which is connected to the elongate tubular member. The cylinder and piston is connected to a source of fluid under pressure by a two position valve connected to a source of fluid under pressure and to exhaust which is moved automatically from one position to the other position at each end of the stroke of the piston.
With such an arrangement, the rate at which the elongate tubular member is moved during a stroke is controlled by throttling the flow of fluid to exhaust. Because the -piston in the cylinder is connected to a rod on one side of the piston, the effective area of the piston on that side is different from the effective area of the piston on the other side. As a consequence, on motion reversal at one end of the stroke there may be a significant dwell period, for example of the order of half a second, which may cause damage to the article being sprayed.
According to one aspect of the invention there is provided a shower assembly control comprising a cylinder and piston of which the piston separates the cylinder into first and second chambers, a rod connected to the piston extending through the second chamber, a two position valve connected to the two chambers and for connection to a source of pressurized fluid and exhaust, the valve being arranged to connect the first chamber to the source of pressurized fluid and the second chamber to exhaust in its first position, and the second chamber to pressurized fluid and the first chamber to exhaust in its second position, throttle means for throttling flow of fluid to exhaust, means for sensing the limit positions of the piston in the cylinder and connected to cause movement of the valve between its first and second positions, and an auxiliary valve connected to the first chamber of the cylinder and operable by the sensing means for connecting the first chamber to exhaust as the sensing means causes movement of the two position valve from its first position to its second position.
In the above described arrangement, the effective area of the piston exposed to the second chamber is smaller than that exposed to the first chamber. As a result and in the absence of the auxiliary valve, there would be a dwell after the valve has moved from its first position to its second position while the pressure in the first chamber reduces to a level for a positive differential pressure to be established in the direction of required movement of the piston. The length of the dwell will depend on the pressure of the pressurized fluid in relation to the effect of the throttling means, which are pre-set to provide a required rate of movement of the piston, and therefore of the elongate tubular member of the shower assembly, between its limit positions.By arranging for the first chamber to be connected to exhaust at this point via the auxiliary valve, which is unthrottled, the rate at which the pressure in the first chamber decreases is substantially increased so that the dwell is reduced to an acceptable level.
Advantageously, the auxiliary valve is controlled so that as soon as the piston moves away from this limit position the auxiliary valve returns to a position closing connection of the first chamber to exhaust so that the flow of fluid out of this chamber is then entirely controlled by the throttle means.
The above described control means may be used with a conventional shower arrangement or with any of the arrangements described in copending Application No. 8214878. Specifically the means for sensing the limit positions of the piston may be switch means and the switch means may comprise fixed outer limit switch means and an intermediate movable limit switch means.
An embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a schematic diagram of an embodiment of control means according to the present invention; Figure 2 is a circuit diagram for the control means of Figure 1; and Figures 3 and 4 show the control means of Figure 1 in alternative conditions.
The control means shown in Figure 1 are intended for controlling a shower assembly comprising an elongate tubular member having a plurality of spray outlet means spaced out along its length and which is connected to a source of liquid under pressure. In use the elongate tubular member is reciprocated axially and the control means shown in Figure 1 is for effecting this axial reciprocation.
The control means comprises a cylinder 1 provided with a piston 2 connected to a piston rod 3 which is, in use, connected to the elongate tubular member of the shower assembly. Piston 2 divides the cylinder into a first chamber 4 and a second chamber 5 through which the piston rod 3 extends. The two chambers 4, 5 are connected to a two position valve 6 which in a first position shown in Figure 3 connects the first chamber to a source of fluid, for example air or hydraulic liquid, under pressure and the second chamber to exhaust. In its second position as shown in Figure 1 the first chamber 4 is connected to exhaust and the second chamber 5 is connected to the source of fluid under pressure.The valve 6 is as shown electrically activated by solenoids S1 and S2 which are energised by sensors P 1 and P2 respectively which detect the presence of the piston 2 at a respective end of its stroke. As shown in Figure 2 sensors P1 and P2 are proximity switches, for example magnetic proximity switches which are normally open and are closed by the presence of the piston which carries a magnet.
In order to control the rate at which the piston, and therefore the elongate tubular member of the shower assembly, moves between its limit positions, throttle means (not shown) are provided in the exhaust passageways through the valve. As a consequence of this, as the piston 2 moves in the direction of the arrow in Figure 3 to its lefthand limit position as shown in Figure 4 the first chamber 4 is pressurized and the second chamber 5 is connected to exhaust. As the piston 2 operates switch P2 solenoid S2 which is connected in series with switch P2 is energised to move the valve 6 to its second position to connect chamber 5 to the source of fluid under pressure and to connect chamber 4 to exhaust.Because the effective area of the piston 2 facing chamber 4 is greater than that facing chamber 5, by virtue of the presence of the piston rod, with the arrangement as described above there will be a significant period during which the piston remains stationary in its limit position while the pressure in chamber 4 drops sufficiently for a positive differential pressure to be established across the piston 2 enabling the piston 2 to move towards the righthand side. This dwell period may be as much as half a second and is sufficient to damage the article being subject to the spray. To avoid this, an auxiliary valve 8 is provided connected to the first chamber 4 and which is biased by a spring 9 to a position in which communication through the. valve is closed.Valve 8 is movable to a second position by a solenoid S3 in which chamber 4 is connected to exhaust, the connection being unthrottled. Solenoid S3 is connected in parallel with solenoid S2 and both are connected in series with proximity switch P2 so that auxiliary valve 8 connects chamber 4 to exhaust for so long as the piston 2 is in its lefthand limiting position causing switch P2 to close.
Thus as soon as switch P2 is closed, chamber 4 is connected by an unrestricted connection to exhuast to cause a rapid reduction in pressure to the point at which a positive differential pressure is established across the piston permitting it to move towards the righthand side. As soon as this occurs solenoid S3 is deactivated and valve 8 returns to its normal condition closing communication with chamber 4.
The above described control means may be used with an entirely conventional shower assembly or maybe used with a shower assembly as described in co-pending Application No.
8214878. As described in that application, one or more intermediate limit switches, e.g. switch P3 as shown in broken lines in Figure 1, may be provided and, where provided, would be connected in parallel with whichever of the two extreme limit position switches P 1, P2 it was intended to replace. As shown in Figure 2 switch P3 is connected in parallel with switch P1 to replace that switch.
The control means may also include means for ensuring that the piston reciprocates at a frequency above a predetermined level and which shuts off the supply of pressurized liquid to the elongate tubular member in the event that the frequency if the piston drops below a predetermined level.
Claims (Filed on 29 July 1983) 1. A shower assembly control comprising a cylinder and piston of which the piston separates the cylinder into first and second chambers, a rod connected to the piston extending through the second chamber, a two-position valve connected to the two chambers and for connection to a source of pressurized fluid and exhaust the valve being arranged to connect the first chamber to the source of pressurized fluid and the second chamber to exhaust in its first position, and the second chamber to pressurized fluid and the first chamber to exhaust in its second position, throttle means for throttling flow of fluid to exhaust, means for sensing the limit positions of the piston in the cylinder and connected to cause movement of the valve between its first and second positions, and an auxiliary valve connected to the first chamber of the cylinder and operable by the sensing means for connecting the first chamber to exhaust as the sensing means causes movement of the two-position valve from its first position to its second pOsition.
2. A shower assembly control as claimed in claim 1, wherein the auxiliary valve is operable to close connection of said first chamber to exhaust as soon as the piston moves from its limit positionfollowing movement of the two-position valve from its first position to its second position.
3. A shower assembly control as claimed in either claim 1 or claim 2, wherein the means for sensing the limit positions of said piston comprise switch means normally in a first state and which are changed to and maintained in a second state by the presence of the piston adjacent thereto.
4. A shower assembly control as claimed in claim 3, wherein at least one of the switch means is adjustabiy positionable for adjusting the corresponding limit position of the piston.
5. A shower assembly control as claimed in either claim 3 or claim 4, wherein said auxiliary valve is biased to its position closing communication between the first chamber and exhaust and is maintained in its position connecting the first chamber to exhaust for so long as the corresponding switch means is in its second state.
6. A shower assembly control as claimed in any one of claims 3 to 5, wherein the switch means in their second state are closed and the valves are solenoids operated, the limit switches being respectively connected in series with
**WARNING** end of DESC field may overlap start of CLMS **.

Claims (8)

**WARNING** start of CLMS field may overlap end of DESC **. which are energised by sensors P 1 and P2 respectively which detect the presence of the piston 2 at a respective end of its stroke. As shown in Figure 2 sensors P1 and P2 are proximity switches, for example magnetic proximity switches which are normally open and are closed by the presence of the piston which carries a magnet. In order to control the rate at which the piston, and therefore the elongate tubular member of the shower assembly, moves between its limit positions, throttle means (not shown) are provided in the exhaust passageways through the valve. As a consequence of this, as the piston 2 moves in the direction of the arrow in Figure 3 to its lefthand limit position as shown in Figure 4 the first chamber 4 is pressurized and the second chamber 5 is connected to exhaust. As the piston 2 operates switch P2 solenoid S2 which is connected in series with switch P2 is energised to move the valve 6 to its second position to connect chamber 5 to the source of fluid under pressure and to connect chamber 4 to exhaust.Because the effective area of the piston 2 facing chamber 4 is greater than that facing chamber 5, by virtue of the presence of the piston rod, with the arrangement as described above there will be a significant period during which the piston remains stationary in its limit position while the pressure in chamber 4 drops sufficiently for a positive differential pressure to be established across the piston 2 enabling the piston 2 to move towards the righthand side. This dwell period may be as much as half a second and is sufficient to damage the article being subject to the spray. To avoid this, an auxiliary valve 8 is provided connected to the first chamber 4 and which is biased by a spring 9 to a position in which communication through the. valve is closed.Valve 8 is movable to a second position by a solenoid S3 in which chamber 4 is connected to exhaust, the connection being unthrottled. Solenoid S3 is connected in parallel with solenoid S2 and both are connected in series with proximity switch P2 so that auxiliary valve 8 connects chamber 4 to exhaust for so long as the piston 2 is in its lefthand limiting position causing switch P2 to close. Thus as soon as switch P2 is closed, chamber 4 is connected by an unrestricted connection to exhuast to cause a rapid reduction in pressure to the point at which a positive differential pressure is established across the piston permitting it to move towards the righthand side. As soon as this occurs solenoid S3 is deactivated and valve 8 returns to its normal condition closing communication with chamber 4. The above described control means may be used with an entirely conventional shower assembly or maybe used with a shower assembly as described in co-pending Application No. 8214878. As described in that application, one or more intermediate limit switches, e.g. switch P3 as shown in broken lines in Figure 1, may be provided and, where provided, would be connected in parallel with whichever of the two extreme limit position switches P 1, P2 it was intended to replace. As shown in Figure 2 switch P3 is connected in parallel with switch P1 to replace that switch. The control means may also include means for ensuring that the piston reciprocates at a frequency above a predetermined level and which shuts off the supply of pressurized liquid to the elongate tubular member in the event that the frequency if the piston drops below a predetermined level. Claims (Filed on 29 July 1983)
1. A shower assembly control comprising a cylinder and piston of which the piston separates the cylinder into first and second chambers, a rod connected to the piston extending through the second chamber, a two-position valve connected to the two chambers and for connection to a source of pressurized fluid and exhaust the valve being arranged to connect the first chamber to the source of pressurized fluid and the second chamber to exhaust in its first position, and the second chamber to pressurized fluid and the first chamber to exhaust in its second position, throttle means for throttling flow of fluid to exhaust, means for sensing the limit positions of the piston in the cylinder and connected to cause movement of the valve between its first and second positions, and an auxiliary valve connected to the first chamber of the cylinder and operable by the sensing means for connecting the first chamber to exhaust as the sensing means causes movement of the two-position valve from its first position to its second pOsition.
2. A shower assembly control as claimed in claim 1, wherein the auxiliary valve is operable to close connection of said first chamber to exhaust as soon as the piston moves from its limit positionfollowing movement of the two-position valve from its first position to its second position.
3. A shower assembly control as claimed in either claim 1 or claim 2, wherein the means for sensing the limit positions of said piston comprise switch means normally in a first state and which are changed to and maintained in a second state by the presence of the piston adjacent thereto.
4. A shower assembly control as claimed in claim 3, wherein at least one of the switch means is adjustabiy positionable for adjusting the corresponding limit position of the piston.
5. A shower assembly control as claimed in either claim 3 or claim 4, wherein said auxiliary valve is biased to its position closing communication between the first chamber and exhaust and is maintained in its position connecting the first chamber to exhaust for so long as the corresponding switch means is in its second state.
6. A shower assembly control as claimed in any one of claims 3 to 5, wherein the switch means in their second state are closed and the valves are solenoids operated, the limit switches being respectively connected in series with
respective ones of the solenoids controlling the two-position valve, the solenoid controlling the auxiliary valve being connected in parallel with the solenoid causing movement of the twoposition valve from its first position to its second position.
7. A shower assembly control substantially as herein described with reference to the accompanying drawings.
8. A shower assembly comprising an elongate tubular member having a plurality of spray outlet means spaced apart along its length, means for connecting the tubular member to a source of liquid under pressure, and a shower assembly control as claimed in any one of the preceding claims, the rod connected to the piston thereof being coupied to the tubular member for reciprocation thereof in the direction of length thereof.
GB08223371A 1982-08-13 1982-08-13 Fluid actuator for shower assemblies Expired GB2125905B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB08223371A GB2125905B (en) 1982-08-13 1982-08-13 Fluid actuator for shower assemblies

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB08223371A GB2125905B (en) 1982-08-13 1982-08-13 Fluid actuator for shower assemblies

Publications (2)

Publication Number Publication Date
GB2125905A true GB2125905A (en) 1984-03-14
GB2125905B GB2125905B (en) 1985-10-23

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ID=10532291

Family Applications (1)

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GB08223371A Expired GB2125905B (en) 1982-08-13 1982-08-13 Fluid actuator for shower assemblies

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6050172A (en) * 1997-04-04 2000-04-18 Emhart Glass S.A. Pneumatically operated mechanism
CN101900148A (en) * 2010-07-12 2010-12-01 无锡市长江液压缸厂 Short-stroke pressure-maintaining high-pressure heavy hydraulic cylinder with high-pressure proximity switches
CN1942675B (en) * 2004-04-16 2012-10-24 费希尔控制产品国际有限公司 Asymetric volume booster arrangement for valve actuator
CN102900784A (en) * 2012-11-09 2013-01-30 王云高 Automatic hydraulic clutch based on manual transmission gearbox

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6050172A (en) * 1997-04-04 2000-04-18 Emhart Glass S.A. Pneumatically operated mechanism
CN1942675B (en) * 2004-04-16 2012-10-24 费希尔控制产品国际有限公司 Asymetric volume booster arrangement for valve actuator
CN101900148A (en) * 2010-07-12 2010-12-01 无锡市长江液压缸厂 Short-stroke pressure-maintaining high-pressure heavy hydraulic cylinder with high-pressure proximity switches
CN102900784A (en) * 2012-11-09 2013-01-30 王云高 Automatic hydraulic clutch based on manual transmission gearbox

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GB2125905B (en) 1985-10-23

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