This invention relates to an adjustable flow restricting valve intended for, for instance, speed control of pneumatic motors. In particular, the invention concerns an adjustable fow restricting valve for controlling the outlet flow of a motor and thereby obtaining a desired velocity of the motor.
The object of the present invention is to make a novel restricting valve which is cheap to manufacture, simple as regards construction and by which it is possible to obtain an accurate setting of the motor speed. This is accomplished by a valve according to the invention as it is defined in the claims.
An embodiment of the invention is hereinbelow described in detail with reference to the accompanying drawing on which
Brief Description of the Drawings
FIG. 1 shows a side-elevation of a standard type control valve including a subplate in which there is mounted two restricting valves according to the invention.
FIG. 1 is partly broken along line I--I in FIG. 2.
FIG. 2 shows a top view of the control valve subplate in FIG. 1. FIG. 2 is partly broken along line II--II in FIG. 1.
FIG. 3 shows a side-elevation of a valve arrangement similar to that in FIGS. 1 and 2 but somewhat modified to enable multiple arrangement.
FIG. 4 shows a top view of two identical control valve subplates clamped together in a multiple arrangement. The view is partly broken along line IV--IV in FIG. 3.
Detailed Description
In the Figures, 10 designates a standard type control valve and 11 designates a subplate associated with the valve. (As the control valve 10 does not constitute a part of the invention, it is not described in detail.) All of the conduit connections of the control valve 10 are located on the subplate 11. Communication between the valve and the subplate is established through the openings 12 to 16. When used in connection with a pneumatic motor 17, the opening 14 is connected to a pressure air source through the conduit 18. The openings 13 and 15 are connected to the motor 17 via service conduits 19 and 20, while the openings 12 and 16 communicate with the air discharge conduits 21 and 22 via air outlet passages in the subplate.
In one of its positions the control valve 10 interconnects the openings 14 and 15 as well as the openings 13 and 12, whereby the part of the motor 17 that is connected to the opening 15 is pressurized, whereas the other part of the motor 17 is drained through conduit 21.
In its opposite position the control valve 10 interconnects the openings 14 and 13 as well as the openings 15 and 16, whereby the motor 17 is powered in its opposite direction.
In order to control the motor speed the subplate 11 is provided with two restricting valves 23, 24 designed in accordance with the invention. These valves are located in the outlet passages of the subplate and are arranged to restrict the outlet flow of the motor 17.
Above there is described an application for a restricting valve according to the invention. Below there is described in detail a restricting valve designed in accordance with the invention.
Each of the restricting valves 24 comprise a housing, in this case constituted by the subplate 11, which housing is provided with an inlet passage 25 and an outlet passage 26. The inlet passage 25 extends between the opening 16 and a boring 27. In the boring 27 there is rotatably supported a tube shaped valve body 28.
The valve body 28 is provided with a recess in the form of an opening 29 which, in response to its angular position, is arranged to fully or partly uncover the inlet passage 25 and connect the latter to the outlet passage 26.
For obtaining angular displacement of the valve body 28 and thereby a proper setting of the restrictor there is provided a maneuver screw 30. The maneuver screw 30 is rotatably supported in a boring 31 which extends transversely relative to the rotation axis of the valve body 28. The maneuver screw 30 is operable from outside the housing 11.
In the shown embodiment of the restricting valve the maneuver screw 30 is constituted by a standard type self tapping screw, the head of which is received in a wider portion 32 of the boring 31. The wider portion 32 of the boring 31 is provided with an annular groove in which is secured a lock ring 34. The purpose of the latter is to prevent axial movement of the maneuver screw 30.
The maneuver screw 30 engages the outer surface of the valve body 28 to form a worm gear by which the valve body 28 is rotatable. The valve body 28 may be preformed with longitudinally extending ribs (not shown) for cooperation with the thread of the maneuver screw 30. However, according to a preferred embodiment of the invention the valve body 28 is made of plastic in which longitudinal slots are cut by the selftapping maneuver screw.
The worm gear which is formed by the maneuver screw 30 and the valve body 28 has a high gear ratio which makes it possible to obtain an accurate setting of the valve body 28.
In the embodiment shown in FIGS. 3 and 4, the passages in the subplate 11 are located so as to enable a multiple arrangement of control valves. Accordingly, the openings 13 and 15 are extended to the bottom surface of the subplate for communication with the pneumatic motor 17 via service conduits 19, 20.
The pressure air supply passages 18 are extended right through the subplates 11. In the downstream subplate, the supply passage 18 is provided with an end closure plug, schematically illustrated in dotted lines at 36.
The flow restricting valves 23, 24 of the two subplates have common outlets in that the borings 27 have been extended throughout the subplates. The tubular valve bodies 28, which form parts of the outlet passages are axially supported in one direction by shoulders 37 in the borings 27. In the opposite direction, the valve bodies 28 are supported by threaded bushings 38 inserted in the outlet passages 26.
The two subplates are clamped together by two screws 39 provided with nuts 40. Other kinds of clamping means may be used in case more valves are put together in a rack. The subplate design does not limit the number of valves to be put together in a multiple arrangement.
The embodiments of the invention may be freely varied within the scope of the invention as defined by the claims.