Position controller

A device for infinitely controlling the position of a controlled member along its axis of movement. The device includes hydraulic actuators coaxially secured to the controlled member and a mechanically and/or manually actuated cylinder is fluidly connected to the hydraulic actuator so that by actuation of the cylinder, both the speed and the position of the controlled member along its axis of movement can be carefully controlled.

BACKGROUND OF THE INVENTION 
I. Field of the Invention 
The present invention relates generally to speed and position controllers 
and, more particularly, to such a device for controlling the speed of a 
controlled member along an axis of movement. 
II. Description of the Prior Art 
There are a plurality of previously known controllers, many of which 
control the position of a member along an axis of movement. These prior 
devices, however, typically cannot infinitely variably control the 
position of the controlled member along its travel. Rather, these prior 
devices can only shift the member to a finite and predetermined number of 
axial positions. 
Furthermore, these previously known devices can control the position, but 
not the speed, of the member. For many applications, such as valve 
actuation, it is desirable to control the speed of the member. Lastly, 
these previously known devices are overly complex in design and, 
therefore, costly to manufacture. Moreover, due to their complexity and 
multiplicity of components, these previously known devices are prone to 
failure. 
SUMMARY OF THE PRESENT INVENTION 
The present invention overcomes the above-mentioned disadvantages of the 
previously known position controllers by providing such a device adapted 
to move a controlled member along its axis of movement which is not only 
of simple construction but which also can infinitely and variably control 
not only the position but also the speed of the controlled member. 
In brief, the controller of the present invention comprises a hydraulic 
actuator having a cylinder and a piston axially reciprocally received 
within the cylinder. The hydraulic piston is coaxially attached to a 
controlled member and the controlled member arranged so that the extension 
of the hydraulic piston shifts the controlled member in one axial 
direction and vice versa. 
A manually and/or mechanically actuated cylinder is fluidly connected to 
the hydraulic actuator so that both the speed and extent of extension or 
retraction of the hydraulic piston can be carefully controlled which in 
turn controls the speed and axial position of the controlled member. In 
addition, the hydraulic actuator cushions the movement of the controlled 
member which further enhances the positioning capabilities of the position 
controller of the present invention.

DETAILED DESCRIPTION OF THE PRESENT INVENTION 
With reference first to FIG. 1, the speed and position controller 10 of the 
present invention is thereshown and includes a controlled member 12 which 
is movable along an axis of movement 14. The controlled member 12 is 
illustrated schematically and may comprise any movable member. Appropriate 
channel guides (not shown) may cooperate with the controlled member 12 in 
order to constrain its movement along the axis of movement 14. It will be 
understood, however, that the ultimate controlled movement may be other 
than the axial movement of the controlled member. For example, the 
controlled member could comprise a crank or lever in order to effect 
pivotal or other types of mechanical movement. 
Preferably a first hydraulic actuator 16 is attached to one axial end 20 of 
the controlled member 12 in a manner to be shortly described, while a 
second hydraulic actuator 18 is similarly attached to the other axial end 
22 of the controlled member 12. Both of the hydraulic actuators 16 and 18 
are substantially identical to each other and each includes a cylinder 24 
with a piston 26 axially reciprocally received within the cylinder 16. The 
volume of a working chamber 28 bounded by the inner axial end 30 of the 
piston 26 and the inner walls 32 of the cylinder 24 controls the axial 
position of the piston 26 relative to the cylinder 24. 
Each of the actuators 16 and 18 includes an elongated piston rod 34 
attached at one end to the controlled member 12 and at its other end 
coaxially with the respective piston 26. The axes of the piston rods 34 
and the hydraulic actuators 16 and 18 are parallel to the axis of movement 
14 and are preferably coaxial. Moreover, as is apparent from the drawing, 
the hydraulic actuators 16 and 18 are arranged in an opposed relationship, 
i.e., movement of the controlled member 12 in one direction along the axis 
of movement 14 simultaneously extends one of the pistons 26 outwardly from 
the cylinder 24 while the other piston 26 is retracted inwardly into its 
cylinder 24. 
Preferably resilient means, such as a helical spring 36, is disposed around 
each piston rod 34 between the piston 26 and the front 37 of the cylinder 
24. For a reason to be later described, the helical springs 36 are 
preferably in a state of compression and, therefore, urge each respective 
piston 26 inwardly into the cylinder 24. 
Preferably, an annular stop member 38 is coupled to and around each of the 
piston rods 34. A stationary stop member 40 is positioned to abut against 
each stop member 38 at the maximum desired travel of the member 12 in 
order to limit the maximum travel of the controlled member 12 along its 
axis of movement 14. Only one stationary stop member 40 is required for 
each annular stop member 38 since the other stationary stop member 40 
effectively limits the travel of the controlled member 12 in the opposite 
direction. 
Two manually actuated cylinders 42 and 44 are provided and are fluidly 
coupled by conduits 46 and 48 to the hydraulic actuators 16 and 18, 
respectively, in a manner to be shortly described. Each of the cylinders 
42 and 44 is substantially identical to each other so that for the sake of 
brevity, only the cylinder 42 will be described in detail. 
The cylinder 42 includes a housing 50 which is preferably cylindrical and 
tubular in cross-sectional shape and closed at its bottom 52. A piston 54 
is axially slidably disposed within the housing 50 so that the piston 54 
sealingly engages the inner walls 56 of the housing 50. 
The piston 54 forms one wall of a working chamber 58 within the housing 50 
and this working chamber is connected by a fluid port 60 and the conduit 
46 to a fluid port 62 open to the working chamber 28 in the hydraulic 
actuator 16. Like the hydraulic actuators 16 and 18, resilient means, such 
as a compressed helical spring 64, is contained within the working chamber 
58 between the piston 54 and the bottom 52 of the housing 50. The spring 
64, thus, urges the piston 54 axially outwardly in a direction away from 
the housing 50. 
The cylinder 42 is mechanically and/or manually operated and, for this 
purpose, an elongated handle 66 is coaxially attached to the upper axial 
end to the piston 54 and and extends outwardly from the housing 50 for 
easy access to the handle 66. 
In operation, assuming the depression of the handle 66 for the cylinder 42, 
hydraulic fluid exhausts from the working chamber 58, through the conduit 
46 and into the working chamber 28 of the actuator 16. An increase in 
volume in the hydraulic actuator working chamber 28 in turn extends the 
piston 26 leftwardly from the actuator 16 and moves the controlled member 
12 leftwardly along its axis of movement 14. 
Simultaneously, the piston 26 in the hydraulic actuator 18 retracts 
inwardly into its cylinder 24. Retraction of the piston 26 in turn reduces 
the volume of the working chamber 28 in the actuator 18 which exhausts 
hydraulic fluid from the working chamber 28 and into the working chamber 
58 in the cylinder 44 via conduit 48. As the volume of the working chamber 
58 of the cylinder 44 increases, the handle 66 and piston 54 extend 
axially outwardly from the housing 50. 
The handles 66 for the cylinders 42 and 44, thus, always move in opposite 
directions due to the opposed relationship of the hydraulic actuators 16 
and 18. Consequently, by manually adjusting the pressure on the handles 66 
not only the speed but also the extent of movement of the member 12 can be 
precisely controlled. Moreover, the precise position of the member 12 is 
accurately and infinitely adjustable along the axis of movement 14 between 
the stop members 40. 
The working chamber 28 in each of the actuators 16 and 18 acts to dampen or 
cushion the movement of the member 12 along the axis of movement 14. 
Moreover, upon extension of the piston rods 34, the helical spring 36 
within the cylinder compresses and urges the pistons 26 to retract in the 
cylinder 24. 
The helical spring 64 in the working chamber 58 of each cylinder 42 and 44, 
serves primarily to offset the gravitational weight of the piston 54 with 
its attached handle 60. The spring 64, thus, insures equilibrium within 
the cylinder 42 or 44 despite the axial position of the piston 54 within 
the housing 50. 
It should be apparent that the controlled member 12 may comprise any 
movable member, such as, for example, a valve actuator, a flow control 
valve, or an actuator to control the stroke of a hydraulic pump. However, 
with reference to FIG. 2, an exemplary controlled member 12 is thereshown 
and comprises a spool valve 70 contained within a valve housing 72 and is 
movable along the axis of movement 14. A plurality of valve lands 74 on 
the spool valve 70 selectively open and close ports 76 formed in the valve 
housing 72 so that both the existence and extent of the fluid 
communication between the ports 76 is determined by the axial position of 
the spool valve 70 along the axis of movement 14. 
It can thus be seen that the present invention provides a novel position 
controller whereby not only the precise position, but also the speed of 
movement of the controlled member 12 can be controlled by simple manual 
manipulation of the actuators 42 and 44. Moreover, the position controller 
of the present invention is not only of simple and inexpensive 
construction, but is also virtually fail-safe and free from maintenance. 
It will also be understood that while the speed and position controller 10 
of the present invention has been described as comprising a pair of 
actuators 16 and 18 and a pair of cylinders 42 and 44, the controller 10 
of the present invention can consist of a single actuator 16 and a single 
cylinder 42. In this event the springs 64 and 36 operate to retract the 
piston rod 34 following an extension of the same. 
Having, thus, described my invention, many modifications thereto will 
become apparent to those skilled in the art to which it pertains without 
deviating from the spirit of the invention as defined by the scope of the 
appended claims.