The invention relates to controls for automobile carwash installations. More particularly, it relates to controls which activate a plurality of subsystems disposed along a conveyor bearing automobiles to be washed through timer-activated logical controls.
The art of constructing and using carwash installations in which an automobile is carried along a conveyor past work stations performing specific tasks--whose totality adds up to a complete cleaning job on the vehicle--are well known in the prior art. Such conventional car washes are based on sensors associated with each, or most, task-performing devices which sense the presence, or approach, of a vehicle and activate the appropriate function.
Such sensors are commonly wand-operated limit switches, proximity switches, or guide rollers attached to particular components, such as rotary brushes. The use of such sensors in the inhospitable environment produced by the water, steam, soap and chemical agent saturated confines of the carwash leads to a large number of maintenance problems and can result in the inefficient use of scarce resources, such as hot water, to overcome positioning errors and other factors associated with mechanical and electro-mechanical direct-acting controls.
Even greater difficulties are encountered in carwash control systems of conventional construction when it is desired to selectively activate certain work stations for particular vehicles; for example by dispensing hot wax where the driver is willing to pay for the higher charges associated with such service.
While proximity sensors and photoelectric devices avoid some of the problems associated with mechanically actuated position indicators, such as possible marring of automobile surface finishes or interfering with external trim, the large variety of shapes, sizes and constructional materials in automobiles make them less accurate and reliable in providing accurate position signals. For these reasons, the use of sensors along the carwash conveyor as parts of the operational control system are attended by many practical difficulties and problems.
It is, therefore, a primary object to the invention to provide controls for a carwash installation incorporating a plurality of active devices disposed alongside a conveyor, in which the position of the individual vehicles is tracked by logical devices, rather than determined by position sensors.
It is a further object of the invention to provide controls for a carwash installation capable of performing a wide range of optional tasks on individual automobiles as they travel along the conveyor, through the assignment of a dedicated program control unit to each vehicle as it enters the installation.
It is also an object of the invention to teach the construction of program control units, and associated control equipment, resulting in economical and reliable control systems for a carwash environment.