Machine element or mechanism – Mechanical movements – Rotary to or from reciprocating or oscillating
Reexamination Certificate
2000-01-06
2001-12-18
Hannon, Thomas R. (Department: 3682)
Machine element or mechanism
Mechanical movements
Rotary to or from reciprocating or oscillating
C074S025000
Reexamination Certificate
active
06330835
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to reciprocating scotch yoke drive mechanisms or translating rotary motion to linear motion, and more particularly for serving in a valve control for a water softener.
It is common to use a scotch yoke to translate rotational movements of a motor drive shaft to reciprocating linear motion. In the case of a control valve for a water softener, it is common to use a scotch yoke drive mechanism to translate rotational movement from the motor drive shaft to linear reciprocal movement on a guide. In such applications, the scotch yoke allows the motor to control the reciprocal linear displacement of a valve control piston.
Conventionally, the scotch yoke member is coupled to the rotary drive source to linearly reciprocate on a track located on the guide. Preferably, the yoke member and the track have a corresponding, complementary rectangular configuration. One disadvantage of known scotch yoke valve control mechanisms is that because of the rotary to linear movement translation and the force exerted from the drive shaft, it is difficult to securely maintain the scotch yoke member in the track on the guide. Another problem with this conventional scotch yoke valve control is that it causes excessive wear on the yoke member and the guide.
Still another problem is that the rectangular configuration often cannot maintain the alignment of the yoke member, such as through component misalignment, causing it to become disengaged from the guide. When that happens, control is lost over the piston shaft attached to the scotch yoke drive mechanism, and the valve cannot be controlled.
Accordingly, a first object of the present invention is to provide an improved scotch yoke mechanism which has better wearability.
Another object of the present invention is to provide an improved scotch yoke mechanism which can better retain the yoke member in the guide by its ability to maintain yoke alignment under a variety of angular stresses.
Yet another object of the present invention is to provide an improved scotch yoke mechanism which maintains alignment of the yoke member in the face of extended operational use and wear.
BRIEF SUMMARY OF THE INVENTION
The above-listed objects are met or exceeded by the present scotch yoke drive mechanism, which features a yoke member with a dovetail sectional configuration for reciprocal sliding on a guide with a complementing slide track. A drive shaft connected to the yoke member provides the force necessary for the movement. As the yoke member receives the rotational movement from the drive shaft, it linearly reciprocates in a slide track located on the guide for movements of the attached piston shaft in order to control the water softener valve. In particular, a sliding formation on the yoke member actually reciprocates on the slide track. The present dovetail configuration greatly improves the consistent functioning of the scotch yoke drive mechanism because it can better maintain the sliding formation on the slide track of the guide. In addition, the more secure maintenance of the sliding formation on the sliding track translates into smoother sliding movements, resulting in better wearability since there is less friction between the sliding formation and the sliding track during operational reciprocating sliding motion. The dovetail configuration also greatly improves the conventional scotch yoke drive mechanism by its ability to maintain yoke alignment under a variety of angular stresses. Lastly, the specific dovetail configuration is also designed to maintain yoke alignment in the face of extended operational use and wear.
More specifically, the present reciprocating scotch yoke drive mechanism is connectable to a motor drive shaft. A yoke member is connectable to the shaft for movement in a linear reciprocal motion. A guide having one or more slide tracks is configured to define a reciprocal sliding path for the yoke member. The yoke member also has a sliding formation configured for slidingly engaging the slide track, and the sliding formation and the slide track have complementary configurations for maintaining alignment of the yoke member during reciprocal sliding motion and engagement of the yoke member in the slide track under a variety of angular stresses.
In another embodiment, the present invention provides a control valve for a water softener, which includes a drive motor with a drive shaft, at least one piston shaft disposed in a valve control cylinder, a yoke member connectable to a crank which moves the yoke member in a linear reciprocating motion, a guide having one or more slide tracks configured to define a reciprocal sliding path for the yoke member, the yoke member has a sliding formation configured for slidingly engaging the slide track, and the sliding formation and the slide track have complementary configurations for maintaining alignment of the yoke member during reciprocal sliding motion and engagement of the yoke member in the slide track under a variety of angular stresses.
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Bearak Justin Blair
Klava Stephen Andrew
Greer Burns & Crain Ltd.
Hannon Thomas R.
Hansen Colby
U.S. Filter Corporation
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