Patent Application
20140224284
This invention relates generally to mobile sweeper/scrubbers such as used in cleaning floors, and is particularly directed to a mobile sweeper/scrubbers having a hydraulic system for powering various subsystems and which is also used to heat the scrubbing water.
Automatic floor sweeper/scrubber machines are well known in the art. Many of these automatic floor sweeper/scrubber machines are self-propelled and typically include a powered brush in a forward location beneath the machine and a vacuum recovery system at the rear of the machine aft of the brush. Cleaning fluid is stored in one compartment and dispensed under operator control to an area adjacent the brush. The rotating brush works the cleaning solution into the floor for removing dirt, debris and grime. The spent solution remaining on the floor aft of the brush is picked up by the vacuum recovery system where it is returned to a separate tank for the spent solution. The cleaning fluid may include one or more cleaning compositions typically in concentrate form which are mixed together, and then diluted with water, with the mixture then applied to the surface to be cleaned. This general description covers industrial and commercial sweeper/scrubber machines designed to clean flat hard floors, carpeted floors and flat outdoor surfaces such as of concrete.
In some cases, the water is heated to an elevated temperature to more effectively and efficiently remove dirt, debris and grime from the surface being cleaned. The heated water breaks down and loosens the dirt, debris and grime, facilitating the action of the cleaning solution(s) on the surface being cleaned. Available sweeper/scrubber machines typically heat the cleaning water using the coolant for the sweeper/scrubber machine's engine which propels the sweeper/scrubber machine. The use of the engine's coolant limits the heat gain of the cleaning solution by the engine's maximum operating temperature and coolant flow rate. This limits the effectiveness of the sweeper/scrubber machine in removing dirt, debris and grime from the surface being cleaned.
Accordingly, it is an object of the present invention to improve the floor cleaning action of a mobile sweeper/scrubber by heating the scrub water to an elevated temperature.
It is another object of the present invention to use an existing system in a conventional floor sweeper/scrubber to heat the scrub water to an elevated temperature.
A further object of the present invention is to heat scrub water in a mobile floor sweeper/scrubber to higher temperatures than currently available for more effectively and efficiently cleaning the floor.
Yet another object of the present invention is to provide a mobile floor cleaner with dual mode operation in terms of heating or not heating the scrub water, where the modes are selectable via a single manual switch.
The present invention is intended for use in a mobile floor sweeper/scrubber having plural operating systems including a scrubber system, and contemplates apparatus for heating scrub water applied to the floor to an elevated temperature comprising: a scrub water reservoir; a hydraulic fluid reservoir; a heat exchanger coupled to the scrub water reservoir via a first water line and to the scrubbing system via a second water line for providing scrub water to the scrubbing system, the heat exchanger further coupled to the operating systems via a first hydraulic fluid line and to the hydraulic fluid reservoir via a second hydraulic fluid return line; and a hydraulic pump coupled to the hydraulic fluid reservoir and to the operating systems for providing hydraulic fluid from the hydraulic fluid reservoir to the operating systems, wherein the hydraulic fluid is heated to an elevated temperature by the operating systems, with the heated hydraulic fluid then provided to the heat exchanger for heating the scrub water to an elevated temperature with the heated scrub water then provided to the scrubbing system from the heat exchanger.
The appended claims set forth those novel features which characterize the scrub water heating system for a floor cleaner of the present invention. However, the scrub water heating system for a floor cleaner, as well as further objects and advantages thereof, will best be understood with reference to the following detailed description of preferred embodiments taken in conjunction with the accompanying drawings, where like reference characters identify like elements throughout the various figures, in which:
Referring to
The scrub water heating system 20 further includes a closed hydraulic system 22 having a hydraulic fluid reservoir 50 containing hydraulic fluid 50a. Hydraulic reservoir 50 is coupled to a hydraulic pump 52 via a first hydraulic fluid line 51. Hydraulic pump 52 is, in turn, coupled to plural hydraulic driven systems 54 by means of a second hydraulic fluid line 53. Hydraulic driven systems 54 in a floor cleaning machine 10 may include a sweeping sub-system for controlling the action, or motion, of one or more sweeper members; a scrub deck assembly for scrubbing the surface being cleaned; an impeller for creating a vacuum; and vehicle drive and steering mechanisms. In the performance of work carried out by the various hydraulically driven systems 54, the hydraulic fluid 50a is heated to an elevated temperature. The action of hydraulic pump 52 distributes the hydraulic fluid, or oil, not only to the hydraulically driven systems 54, but also displaces the hydraulic fluid from the hydraulically driven systems to the heat exchanger 32 by means of a hot hydraulic fluid line 58. The hot hydraulic fluid is displaced through the heat exchanger 32 and exits from the heat exchanger via a first outlet port 78 to first and second hydraulic fluid return lines 60 and 60a. The first and second hydraulic fluid return lines 60 and 60a are coupled to the hydraulic reservoir 50 for returning the cooled hydraulic fluid 58 to the hydraulic reservoir.
The operation of heat exchanger 52 in heating the water discharged from water reservoir 28 prior to the water being provided to the cleaning machine's scrub system 36 will now be described with reference to
As noted above, the hydraulic fluid 50a is heated to an elevated temperature as it passes through the cleaning machine's hydraulically driven systems 54. The heated hydraulic fluid 50a is then provided via hot hydraulic fluid line 58 to a first input port 76 of heat exchanger 32. Simultaneously, ambient scrub water 28 is directed via the ambient water line 30 to a second input port 80 of the heat exchanger 32. By means of heat exchanger 32, the heat of the hot hydraulic fluid 50a is transferred to the ambient scrub water. The heated scrub water then exits the heat exchanger 32 via a second outlet port 82 and travels via hot water line 34 to the cleaning machine's scrub system 36. The hydraulic fluid 50a is at its highest temperature as it enters the heat exchanger 32 at the first input port 76. Thus, the heat transferred to the scrub water 28 exiting the heat exchanger 32 at the second outlet port 82 and provided to the cleaning machine's scrub system 36 is maximized. The hydraulic fluid is returned from the heat exchanger 32 to the hydraulic fluid reservoir 50 via the heat exchanger's first outlet port 78 and the first and second hydraulic fluid return lines 60 and 60a.
The hydraulic fluid 50a is heated by the cleaning machine's hydraulically driven systems 54 to a temperature on the order of 200° F. Most engines used in a typical floor cleaning machine have a thermostat limited to engine operating temperatures on the order of 180° F. Therefore, heating the scrub water 28 using the cleaning machine's closed hydraulic system 22, rather than the motor coolant, provides on the order of an additional 20° F., or 10%, of heat to the scrub water.
The above-cited numbers are specific to the mobile sweeper/scrubber in which the present invention was installed. Other temperature values may be realized with the present invention installed in other types of sweeper/scrubbers depending upon machine loadings and the system specific components being used. In addition, the thermostat-limited operating temperatures combined with the low coolant flow rates of the engines typically incorporated in conventional floor sweeper/scrubbing cleaning machines represent an overall inferior approach to the heating of the sweeper/scrubber scrub water when compared with the approach of the present invention.
The scrub water heating system 20 may further include an electric solenoid valve 40 coupled to the hot hydraulic fluid line 58 and further coupled via a by-pass line, or conduit, 38 to hydraulic fluid return lines 60 and 60a. Solenoid valve 40 is coupled to a first end of by-pass line 38 which is coupled at its opposite end to hydraulic fluid return lines 60 and 60a. Solenoid valve 40 in a first control state directs hot hydraulic fluid via hot hydraulic fluid line 58 to the first inlet port 76 of heat exchanger 32 for heating the ambient scrub water to an elevated temperature. In a second control state, solenoid valve 40 directs the hot hydraulic fluid to hydraulic fluid return line 60a via the by-pass line 38. In this mode of operation, the scrub water 28 is not heated and is delivered to scrub system 36 at ambient temperature. Also in this mode of operation, hot hydraulic fluid is prevented from flowing from the discharge end of by-pass line 38 via hydraulic fluid return line 60 to heat exchanger 32 by the presence of hydraulic fluid previously provided to the hydraulic fluid return line 60 from heat exchanger. This feature allows the mobile floor sweeper/scrubber of the present invention to be selectively operated in a first scrub water heating mode, or in a second mode wherein the scrub water is maintained at ambient temperature. However, as described above the scrub water heating system of the present invention may also be provided in a mobile floor sweeper/scrubber on a continuous, non-interrupted basis. In addition, incorporating the by-pass line 38 on the hydraulic side of the heat exchanger 32 eliminates the possibility of hot water remaining within the heat exchanger, such as if it is trapped, while continuing to be heated which could result in excessive pressure build-up within the heat exchanger and the possibility of damage to the system, or even an explosion. This possibility is avoided by isolating and removing the source of heat, i.e., the hot hydraulic fluid 50a, from the heat exchanger 32 when heated scrub water is not called for or desired.
Heat exchanger 32 in a preferred embodiment is comprised of a high heat conducting metal, or of a high heating conducting plastic, ceramic or composite material, and is of the stacked plate type of heat exchanger wherein the scrub water 28 and hydraulic fluid 50a pass through the heat exchanger in adjacent, alternating fluid paths 46 each formed by a pair of adjacent stacked plates 48. The ambient water flows in the direction of arrow 55, while the heated hydraulic fluid flows in the direction of arrow 56. The scrub water 28 and hydraulic fluid 50a preferably flow in opposite directions to maximize heat exchange. Each fluid path is linear, rectangular in cross section and generally flat. Heat exchanger 32 is also preferably disposed, or wrapped, in a thermal insulator 70. However, the present invention is not limited to the heat exchanger disclosed herein and could equally as well incorporate virtually any of the conventional heat exchangers currently available for heat exchange applications at the range of temperatures discussed herein.
While particular embodiments of the present invention have been shown and described, it will be obvious to those skilled in the relevant arts that changes and modifications may be made without departing from the invention in its broader aspects. Therefore, the aim in the appended claims is to cover all such changes and modifications that fall within the true spirit and scope of the invention. The matter set forth in the foregoing description and accompanying drawings is offered by way of illustration only and not as a limitation. The actual scope of the invention is intended to be defined in the claims when viewed in their proper perspective based on the prior art.
