Single control paint sprayer

Details Single control paint sprayer Single control paint sprayer

2000-06-06

2001-12-11

Scherbel, David A. (Department: 3752)

Fluid sprinkling, spraying, and diffusing

With system fluid relief or return to supply

C239S569000, C239S581100, C239S353000, C137S560000

Reexamination Certificate

active

06328223

ABSTRACT:

BACKGROUND OF THE INVENTION
This application relates to the art of controls and, more particularly, to manually operable single controls that perform multiple functions. The invention is particularly applicable for use with airless paint sprayers and will be described with specific reference thereto. However, it will be appreciated that the invention has broader aspects and that certain features of the invention can be used for other purposes.
Airless paint sprayers typically have an on/off switch, a bypass valve for priming and pressure relief, and a pressure adjusting valve for adjusting the pressure at which paint is supplied to the spray gun so that the pressure is suitable for the project at hand.
It is common to have a separate manually operable control for each of the on/off switch, the bypass valve and the pressure adjusting valve. A typically recommended operating procedure advises a user to first move the pressure adjusting control to the low pressure position and the bypass valve control to the open or prime position before the switch is turned on. After the switch is turned on by operating the switch control, the user must move the separate pressure adjusting control to a medium pressure setting and wait for the unit to prime. Once the unit is primed, the user must move the separate bypass valve control to the spray position and move the separate pressure adjusting control to the desired pressure setting before spraying can begin.
In devices of the type described, a user does not know the pressure setting of the pressure adjusting valve unless the sprayer has an attached pressure gauge. In addition, arrangements of the type described permit a user to turn the switch to its off position while leaving the unit at fill pressure. This is undesirable because a user may try to remove a hose or misdirect spray by not realizing that the unit remains under pressure even though it is turned off.
An arrangement has been proposed that will not allow a user to shut the sprayer off while it is under pressure but it includes two separate controls that are arranged to force a user to operate them in a certain order.
It would be desirable to have a simplified control arrangement that operates in a predetermined sequence and avoids problems associated with existing arrangements.
SUMMARY OF THE INVENTION
A paint sprayer of the type described has a single manually operable control that operates the on/off switch, the bypass valve and the pressure adjusting valve. The single control automatically operates the on/off switch, the bypass valve and the pressure adjusting valve in a predetermined proper sequence both when the sprayer is turned on and when it is turned off.
In accordance with a preferred arrangement, the manually operable control is rotatable between opposite end limits or end positions, with one end limit being a switch off position and the opposite end limit being the highest pressure setting with the switch on. In the one end limit position of the control with the switch off, the bypass valve is open. Movement of the control a short distance away from the one end limit position to a priming position turns the switch on while leaving the bypass valve open for priming the unit. Further movement of the control away from the one end limit position closes the bypass valve while leaving the switch on and allows selective adjustment of the pressure adjusting valve over a range of pressures from the lowest pressure adjacent to the priming position to the highest pressure at the opposite end limit position.
In accordance with one arrangement, the manually operable control includes a rotatable control plate having an arcuate slot therein. An end portion of a valve stem on the bypass valve projects through the slot and has a bypass valve cam follower thereon for cooperation with a bypass cam on the control plate adjacent the slot to open the bypass valve when the control plate is at and adjacent to the one end limit position of the control. The bypass valve opens as the control approaches the switch off position so that the pressure is relieved before the unit is turned off. Obviously, other arrangements are possible for providing cooperative relationship between the manually operable control and the bypass valve.
In accordance with another aspect of the application, the control has a switch cam thereon for cooperation with a switch cam follower to turn the switch on and off. In one arrangement, the cam on the control is a cam recess and the switch cam follower moves into the switch cam recess to open a normally closed switch. In another arrangement, the switch cam on the control is a cam projection that cooperates with the switch cam follower to positively turn the switch off.
In accordance with another aspect of the application, the pressure adjusting valve includes a rotatable adjusting member that rotates with the manually operable control. Rotation of the manually operable control over a range of pressure settings allows adjustment of the pressure adjusting valve to regulate the pressure at which the paint is pumped.
In the arrangement of the present application, the bypass valve always is open to relieve pressure in the unit before the control moves to a position for turning the switch off. Thus, a user cannot turn the sprayer off while leaving it under pressure unless the power is interrupted such as by separation of the power plug from the socket while the switch is on and the sprayer is under pressure.
It a principal object of the present invention to provide an airless paint sprayer with a single manually operable control that operates an on/off switch, a bypass valve and a pressure adjusting valve.
It also is an object of the invention to provide such a control that has a bypass cam and a bypass valve cam follower arrangement for operating the bypass valve and moving same between its open priming and pressure relieving position and its closed position.
It is a further object of the invention to provide such a control wherein the sprayer cannot be turned off while it is under pressure.
It is another object of the invention to provide such a control that enables a user to operate the sprayer in a proper sequence without requiring any conscious effort or decisions.


REFERENCES:
patent: 3614351 (1971-10-01), Wojcik
patent: 4834287 (1989-05-01), Walsh et al.
patent: 4928722 (1990-05-01), Walsh et al.

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