US 3807451 A
A pneumatic timer device comprising a body housing a valve, an escapement operatively connected to such valve, means for setting the escapement and means for limiting the setting and hence the operable period of the said escapement.
Claims available in
Description (OCR text may contain errors)
United Statesv Patent 1191 Howlett Apr. 30, 1974 1 PNEUMATIC TIMER. DEVICE  References Cited  Inventor: Robert Stanley Howlett, Auckland, UNITED STATES PATENTS New'Zealand 3,045,698 7/1962 Whitney 251/64 X 3,638,682 2/1972 Heyer l37/624.l2 [731 Asslgnee- Beam Products 1,085,012 1/1914 Bopp. 74 35 x Auckland, New Zeakmd 3,082,790 3/1963 Whitney... 251/64 Filed, Oct. 10 1972 1,060,554 4/1913 Ott 251/64 X  Appl. N0.: 296,227 .Primary ExaminerHenry T. Klinksiek Attorney, Agent, or Firm-Millen, Raptes & White  Foreign Application Priority Data 7, 7 ABSTRAC Oct. 18, 1971 New Zealand 165189 I [5 v A pneumatic timer device comprlsmg a body housmg us Cl v 137/624 11 251/64 a valve, an escapement operatively connected to such  Int -Cl I i 6. 21/00 valve, means for-setting the escapement and means for [581 111.1 1561;111:1111;..11:"1s77a51.11 624.12: limiting the'setfing and hence the operable period of the said esc'apernent. 1 ,7
' 6 .Claims, 4 Drawing Figures PNEUMATIC TIMER DEVICE BACKGROUND OF'TI-IE INVENTION measure of accuracy of the selected time, additional equipment by way of regulators and filters need to be employed to maintain reasonable stable conditions of the air used.
With the prior art disadvantages in mind, it is an object of this invention to provide an improved pneumatic timersAnother object of this invention is to provide a pneumatic timer with a time period dependent on the accuracy of a mechanical escapement.
A further object is to provide a pneumatic timer with a time period which is not influenced by variations in the air supply.
A still further object is to provide a pneumatic timer device which provides a means of supplying or interrupting the flow of a working medium for a preselected period of time and to maintain a close tolerance of repeatability of the selected time irrespective of variations occurring in the working medium used.
SUMMARY OFTI-IE INVENTION Broadly the invention consists of a pneumatic timer device comprising a body housing a valve, an escapement operatively connected to such valve, means for setting the escapement and means for limiting the setting and hence the operable period of the said escapement.
DETAILED DESCRIPTION In the following description of the invention reference will hereinafter be made to the accompanying drawings in which:
FIG. 1 isa sectional elevational view of the timer,'
FIG. 2 is sectional elevatio nal view from the opposite side to that of FIG. 1,
FIG. 3 is a front end view of thetimer showing a dial and dial plate and FIG. 4 is a detail sub-assembly showing the escapement mechanism, a pinion and cam.
In more fully describing the invention as a preferred embodiment the timer mechanism is contained in a body or housing 10.,To control the flow of the working medium, e.g., air, a control valve 11 is located near the rear of the housing. This valve 11'is a mechanically operated valve of a type commonly used and which is provided with a ball 12 which requires to be depressed in order to change its operating condition. To operate the ball 12 of the valve 11 there is provided a circular cam 13 which is mounted on the shaft 14 projecting from an escapement mechanism 15 and which has on its periphery a depression 16 into which the ball 12 in the valve 11 will seat when the said valve 11 is in its normal unoperated condition.
The escapement mechanism 15 is of the type which is wound by rotating the shaft 14 which passes through the said escapement mechanism 15, and which, when released will allow the said shaft 14 to gradually return to its unwound position under the control of the mechanism. In the preferred form the shaft 14 projects from both sides of the escapement mechanism 15, i.e., transverse to the plane of the mechanism, and on the shorter of these extensions, which faces the front of the timer housing 10, a circular disc 17 is fitted. This circular disc 17 is fitted with an outstanding projection 18 at a distance from its centre.
On the front of the housing a dial plate 19 is detachably fitted said plate 19 being provided with calibrations indicating time related to the angular movement of the escapement shaft 14. The escapement mechanism and the dial plate 19 correspond with each other in that the dial 20 is calibrated in accordance with the time associated with the said mechanism 15. When one escapement mechanism is replaced by another escapement mechanism the corresponding dial plate replaces that on the unit at the time. A dial 20 is fitted to a shaft 21 journalled in the front of the housing 22, i.e., centrally in the dial plate 19 and transverse thereto, and is provided with means of locking 23. This central dial 20 has on its periphery a pointer for indicating the time for which the timer has been set.
' tioned in such a manner that they are concentric and therefore the projections 25 on the dial disc 24 limits the rotation of the escapement shaft 14 when the projections 18 and 25 come into contact with oneanother.
The winding of the escapement mechanism 15 can be accomplished in a number of ways. In the preferred form, a pinion 26 is fitted to the longer extension of the escapement shaft 14 near the escapement mechanism 15. A rack 27 is positioned so as to engage the teeth of the pinion 26. For convenience and compactness the rack 27 is of a hollow cylindrical nature and is located in a chamber 28, said chamber 28' lying within the housing 10 and being located transversely to the escapement shaft 14. The; rack 27 is hollow so that the stem of a piston 29 maybe located therein. The piston 29 runs within the chamber 28 and is returned by an expansion spring 30 being located'by one end in the hollow stem of the piston 29 and located at its other end on a locating lug 31 which seals the chamber 28 at its terminal point in the housing wall 32. The opposite end of the chamber 28 is sealed by an inlet connection 33. In the normal position the piston head is adjacent the inlet connection 33 at the end of the chamber 28. The piston 29 is used for transmitting winding power for the escapement mechanism 15, and is returned under the influence of the spring 30 so as to cause variations of the rate of movement of the escapement shaft 14 due to the friction between the seal 34 of the piston 29 and the cylinder or chamber wall. An opening 35 extends transversely through the body 10 and cuts into, the chamber 28 so that the pinion 26 can engage with the rack 27. This opening 35 provides a passage for the escapement shaft 14 from the front of the housing 10 to the rear thereof.
In use the cycle of operation is as follows. Pressurized air is applied to the end of the piston via the inlet or port connection 33 causing the piston 29 and rack 27 to be moved which in turn rotates the pinion 26 and escapement shaft 14. As the escapement mounted disc 17 rotates with the shaft 14 the projection 18 thereon comes into contact with the corresponding projection 25 on thedisc 24 consequently limiting the amount the shaft 14 is rotated and hence the amount the escapement mechanism is wound. As the shaft 14 commences its rotation the cam 13 also rotates causing the ball 12 in the valve 11 to be depressed and so cause the valve 11 to change its condition.
Immediately, air pressure is removed from the piston 29, the said piston returns to its home position under the influence of the spring 30. At this point the time period commences and the escapement shaft 14 is under the control of the escapement mechanism 15. As the escapement mechanism 15 unwinds the shaft 14 rotates in the opposite direction until the depression 16 in the cam 13 reaches a point where the ball 12 of the valve 11 will drop into the said depression 16 and cause the valve 11 to change its condition. It is essential in many cases that the valve 11 which is being controlled by the timer, is operated near instantaneously and if the cam 13 is fixed rigidly to the shaft 11 this is not possible. In the preferred form therefore the pinion 26 is connected to the cam 13 by pins extending between opposite faces of the pinion 26 and cam 13 in such a manner as to allow a sufficient amount oflost motion" between the two so that as the ball 12 reaches the commencement of the depression 16; pressure behind the ball 12 is sufficient to cause the cam 13 to take up the lost motion and allow the said ball 12 to enter the depression 16 instantaneously.
The invention therefore provides a means of supplying or interrupting a flow of air, or other medium, for a preselected period of time. The main feature of the invention, however, being that the set period of time can be repeated and with a close tolerance the time period does not fluctuate because of variations occurring in the air or other fluid used, by way of cleanness and pressure.
What is claimed is:
l. A pneumatic timer device comprising a body housing, an escapement mechanism wound by rotating an escapement shaft connected to said escapement mechanism, the release of said mechanism causing the return of said shaft to its unwound position, the escapement shaft extending transversely of a chamber within the body with both ends of said shaft projecting clear of the chamber, one end of said shaft providing an output and the opposing end having a first projection mounted thereon, the projection being radially disposed of and axially parallel with the axis of said shaft and being operatively co-planar to a second projection correspondingly disposed on a rotatable timing shaft opposingly positioned in co-axial relationship with said escapement shaft, said timing shaft extending from an operable limiting member outside the timer body such that said timing shaft may be rotated by said operable member an amount corresponding to a desired time interval whereby said second projection thereon will be contacted by said first projection on said escapement shaft upon a corresponding rotation of said escapement shaft, and a pinion mounted on said escapement shaft and engaging a rack set in a linear interworking relationship with a piston slidably mounted in said chamber, said piston being spring biased to tend to close a pressurized air inlet connection to said chamber.
2. A pneumatic timer as claimed in claim 1 further including a cam mounted on the output end of said escapement shaft, said cam having a peripheral transverse edge provided with a depression into which a sprung outwardly contact member of a unit controlled by said timer can enter for changing a condition of the unit, and wherein said first and second projections on said escapement and timing shafts are mounted upon a first disc and a second disc, respectively, said discs being rigidly secured to respective shafts, and wherein said operable member consists of a dial mounted on said timing shaft, locking means being associated with said dial so that said second projection on said timing shaft can be locked in a desired position, and a dial plate detachablymounted on the exterior of said timer body and calibrated to indicate time intervals relative to the angular movement of said escapement shaft.
3. A pneumatic timer as claimed in claim 2 wherein said pinion is positioned adjacent said cam and comprises pins extending between opposing faces of said pinion and said cam for operably connection said cam to both said pinion and said first shaft in a manner allowing a sufficient amount of lost-motion between said cam and pinion to ensure that said sprung contact member enters the depression of said cam substantially instantaneously.
4. A pneumatic timing device as claimed in claim 2, wherein said unit is a ball valve, and said sprung outwardly contact member is a ball of said ball valve.
5. A pneumatic timer device as claimed in claim 1 wherein an opening is provided within said body housing, said opening being positioned so as to cut into the side of said chamber and allows said pinion mounted on said escapement shaft to engage with said rack located within said chamber.
6. A pneumatic timer device as claimed in claim 5 wherein said piston is biased by an expansion spring which causes the head of said piston to normally position itself against said inlet connection, said piston remaining in such position until compelled to move within the chamber under the influence of pressurized air introduced through the inlet.