GB2290021A

GB2290021A - Brush pressure control system for floor cleaning machine

Info

Publication number: GB2290021A
Application number: GB9511875A
Authority: GB
Inventors: William Anthony Briscoe
Original assignee: BRISCOE WILLIAM A
Current assignee: BRISCOE WILLIAM A
Priority date: 1994-06-10
Filing date: 1995-06-12
Publication date: 1995-12-13
Also published as: GB9511875D0

Abstract

Cleaning or sweeping apparatus for example of the pedestrian type, has means for biasing the brush or brushes 27 against the surface to be cleaned or swept at a desired value and preferably at a controllably variable value. Working pressures are measured and displayed on an operator's console 24 and may be kept fairly constant despite uneven floors by a feedback control circuit. An electronic control circuit including a microprocessor is described. The biasing means preferably comprises long springs 2 mounted in spring tubes 1 which are compressed by an electrical or hydraulic actuator 10. <IMAGE>

Description

CLEANING HEAD PRESSURE CONTROL DESCRIPTION The present invention relates to cleaning head pressure control, particularly for floor cleaning or sweeping machines.

Traditionally the brush pressure in such machines is not controllable by an operator but is dependent upon parameters set in the factory or by service engineers.

Thus present machines are unsatisfactory since the set pressure may be inappropriate to the floor surface or the cleaning job to be accomplished resulting in damage to floors or brush heads or unsatisfactory results.

According to the present invention there is provided means for controlling the working pressure of a cleaning head in a cleaning machine comprising means for applying a variety of pressures to the cleaning head, means for monitoring and/or measuring the pressure applied, input means operable for an operator to select a desired pressure, comparator means for comparing the desired pressure with the measured pressure and for generating a control signal in response to the comparison result and means for applying the control signal to control the pressure applying means.

The present invention thus enables an operator to control cleaning head pressure and thus to have control over the cleaning power of the machine and the rate of brush wear.

Preferably an electronic processor is provided for the comparator means. The pressure measuring means may register pressure through an electronic resistive element a strain gauge, a pressure transducer or a piezoelectric sensor and display the measured value on the operator's console in digital form.

Preferably the brush pressure exerted by the brush head is measured directly, for example by measuring the torque directly at the brush head so that a constant brush pressure can be maintained, and the pressure can be read back to a gauge showing pressures.

According to a preferred embodiment of the present invention there is provided a cleaning or sweeping apparatus comprising: a frame; a brush assembly mounted on the frame for movement towards and away from a surface to be brushed; a biasing means acting between the frame and the brush assembly to apply to the brush assembly a bias towards the surface; means for measuring the pressure exerted by the brush assembly on the surface; and means for displaying the measured pressure.

Preferably means are provided for input of a desired brush pressure by an operator which input may be displayed, and feedback means are arranged to control the applied brush pressure as a function of the measured pressure and the operator input desired pressure to maintain the applied pressure at a value substantially within preset boundary values. The measured and desired pressures may be compared, eg by an electronic processor.

Operator input may be inhibited while the apparatus is moving.

According to a second preferred embodiment of the invention there is provided a sweeping or cleaning apparatus comprising; a frame; a brush assembly mounted on the frame; means for moving the brush assembly towards and away from a surface to be cleaned; biasing means acting between the frame and the brush assembly to apply to the brush assembly a selectable bias towards the surface; means for monitoring and/or measuring the applied working pressure; means for displaying an indication of the measured working pressure; means for operator entry of a desired working pressure for the brush assembly.

According to another preferred embodiment of the invention there is provided apparatus for controlling brush head pressure in a cleaning or sweeping machine, the apparatus comprising: analogue to digital conversion means for converting input signals representing respectively a measured brush pressure and an operator chosen brush pressure; storage means for predetermined system parameters; computing means programmed to compare the two input signals and to generate a control signal in response to the comparison and the predetermined system parameters.

The state of the power supply source may also be monitored and the brush operation inhibited when the battery state is below a preset value or when the usage time exceeds a predetermined value.

For a better understanding of the invention and to show how the same may be carried into effect, reference will now be made to the accompanying drawings in which: Fig. 1 shows a cross-section elevational view of brush assembly for a cleaning apparatus according to the invention; Fig. 2 shows an alternative arrangement of part of the assembly of Fig. 1 Fig. 3 is a part cut-away perspective view of a cleaning apparatus incorporating the assembly of Figs. 1 and 2.

Fig. 4 is a diagrammatic representation of a control system for a cleaning apparatus according to Figs. 1 to 3; and Fig. 5 is a circuit diagram illustrating one embodiment of the control system of Fig. 4.

In Fig. 1, the brush assembly comprises two spring tubes 1, containing springs 2. The right hand tube 1 in the figure is shown in cut-away to illustrate spring 2. Each spring is fixed at one end to the upper end of the tubes at 3 and at the other end to a spring rod 4 which slides through an aperture 5 into the respective spring tube 1. The spring rods 4 are connected together by a bolt 6 and are fixed via assembly 7 to the brush support plate 8 to which brush head or heads 27 are connected.

The tubes 1 are prevented from rotating or skewing by a steadying plate 9. An actator 10 is secured to a bulkhead of a cleaning machine. Actuator 10 drives actuator rod 12 which is shown in substantially closed up position in the figure.

The actuator rod 12 is fixed by a pin 13 to actuator plate 14 which is clamped to both spring tubes 1 by clamping bolts 15.

Thus as the actuator drips the actuator rod 12 downwards, the spring tubes 1 move downwaras ana the springs 2 are compressed causing a higher pressure to be exerted on the brush head assembly whilst still providing suspension to accommodate uneven floors and brush wear. Ti?-cailyZ the effective spring lengths, in an uncotnpressed state, are around 15 inches and this is particularly suitable or a 25/32 inch brush pressure system. Suc an arrangement can provice a range of 0 to 4501b pressure in a loaded pedestrian cleaning machine fitted with apparatus according to the invention, compared to the maximum 2001b pressure available using known apparatus. Of course other forms of biasing means could be used. A torsion spring has the advantage of taking up less vertical space in a cleaning machine. Also, a torsion spring generally has a low spring rate which is particularly suitable for this purpose.

Gas struts or hydraulic or pneumatic systems could also be used.

The pressure can be further adjusted by changing the springs for different length ones or different strengths the clamping position of the spring tubes can be altered. However these changes require a service engineer.

The system is particularly adjustable since the actuator can be stopped anywhere in its stroke.

Usually brush support plate 8 will be attached to â pair of circular or elliptical brushes rotating in a plane generally parallel to the floor (or surface to be cleaned or swept) . However, up to four brushes are in use in some cleaning machines and the apparatus of the invention could be used to control all such four brushes together or alternatively individually (in which case separate actuators would be used for each) . Of course a cylindrical brush head could be equally easily controlled mounted on the brush support plate 8 or alternatively controlled at each end of its shaft by respective separate assemblies according to Fig. 1.

A strain gauged beam 20 which may be used to measure the brush pressure is located under the spring tube clamp plate 18.

Fig. 2 illustrates an alternative arrangement of the actuator plate 14 wherein the plate has a U-shaped cross section as shown so that it is clamped to the spring tubes 1 in a plane spaced from that in which it is clamped to the actuator rod 12. This arrangement enables particularly low brush pressures to be achieved even with heavy duty springs.

In Fig. 3 the brush assembly of Fig. 1 is shown mout in a pedestrian cleaning apparatus. Like parts are indizatec by like reference numerals and a pair of spring tubes 1 are attached to actuator rod 12 by actuator plate 14. The actuator 10 is fixed by tie bar 15 to the apparatus frame 16.

A second pivoted mounting 17 connects the assembly 7 and brush support plate 8 to frame 16. The brushes themselves are not shown in Fig. 3 but are mounted below the support plate 8 behind the protective flange 17 and are driven by scrub brush motors 18 (one of which is shown in Fig. 3).

Fig. 3 also illustrates the relative positions of the water tank or tanks 19, the battery pack 20 for driving the scrub motors 18 together with the transverse drive of the cleaning apparatus. The direction of transverse drive is controlled by a handle 21. A squeegee 22 has suction applied via vacuum motor 23.

Additionally a brush head pressure control panel 24 is provided within the operator's view.

In Fig. 4 the brush assembly is shown schematically in side view and a control system is illustrated as a block diagram.

The position of the brush head 27 relative to the floor to be cleaned, is controlled by electric or hydraulic actuator 10 lifting or lowering the brush head via an actuator rod which compresses springs in spring tube 1. Other resilient means such as a gas strut may be used for applying pressure to the brush head against the floor and of course other means may be used to control the position of the brush head such as hydraulic or pneumatic means. Details of the actuator 10 has been described above.

A pressure sensor is located at one of the positions labelled 4 though it may be positioned anywhere in the cylinder or in the arm or in the bottom of the actuator. In use this sensor monitors the pressure applied by the brush to the floor and generates a signal 25. The pressure sensor may be a strain gauge 20 on actuator plate 14 as shown in Fig. 1 or a piezoelectric sensor or position sensor. Alternatively the securing pin " 1 Fi. l) which connects the assembly to the apparatus trams, may be used as a shear gauge to measure pressure. Amplifier 26 converts this pressure signal 25 to a value usable in the subsequent circuitry.

The control panel 24 is provided within sight of an operator. It has a pressure select knob 28 by which the operator can pre-select a particular pressure. A rocker switch 29 lifts or lowers the brush head 27 relative to the floor depending on the switch position. A digital display 30 illustrates the pressure of the brush head 27 on the floor, as measured by the pressure sensor.

A processor 31 compares the measured pressure signal with the operator selected pressure and generates a control signal accordingly to control (as necessary) the actuator to make the measured pressure substantially the same as the selected pressure.

This processor may be of simple construction such is comprising an electronic comparator and amplifier circuit, or it may comprise a standard CPU unit in chip form.

Power for the electronic components is supplied by the on-board battery 12 or by alternative low power battery sources.

The circuit of Fig. 5 can be used as the control system for the system. It comprises standard integrated circuits including a programmed micro-controller or micro-processor U5, power supply IC's U1, U4 and U7, non-volacile memory store U3, analogue to digital converter U6 and buffer amplifier U2 A measured pressure signal from a pressure bridge or strain gauge mounted in the cleaning head is input to the microprocessor U5 via instrumentation amplifier U6 and analogue to digital converter (ADC) U6.

System variables are stored in the non-volatile memory store U3.

The state of external switch inputs on the cleaning machine are sampled via buffer JD4 The microprocessor U5 makes appropriate calculations based on the sampled values and the set system variables and outputs control signals via buffer amplifier U2, relays P2l, RL2 and RL3 and buffer JP1 to contact relays to operate the actuator on the cleaning machine itself. For example, when relay RL1 is tripped 35 volts are applied to the cleaning head lowering actuator, when relay R;2 is tripped 36 volts are applied to raise the cleaning head, and when relay RL3 is tripped the drive control or traction cf the cleaning machine is inhibited.A further relay may optionally be provided to inhibit the brush motor under certain predetermined circumstances - such as when the battery is low to protect the warranty on the battery.

The SENSE input on buffer jl senses whether or not the cleaning machine is moving. f it is, then the circuit inhibits pressure changes to avoid damaging the brushes.

Buffers JP2 and JP3 supply signals to the machine control panel to display the actual measured pressure indication and the set value indication respectively on LED displays.

The circuit comprising MosFet Qi, resistors Rld, R15, together with diode D10 and capacitor Ci8 is a power-up hold off circuit to prevent the relays pulsing during switching to avoid spurious operation of the actuator. This is optional and can be accomplished in a number of different ways as will be immediately apparent to anyone skilled in the art.

Circuits JP6 and JP7 are unused as shown.

Further modifications can be included in this circuit, for example a battery monitor could advantageously be incorporated to record the total usage time and monitor the charge state of the battery. sunder certain predetermined conditions, as programmed into the system parameter memory circuit U3, the cleaning brushes would be automatically raised. Such conditions would typically be long battery usage and/or low battery charge The operator would then necessarily have to take the machine back to the depot to recharge or replace the battery thus preserving the warranty on the battery.

The control circuit 5~ the innen.on is very finely tunable and achieves extremely accrate pressure settings for the brush head.

The micro-controller US is preferably programmed to always effect pressure changes in a direction such that the brushes are moved downwardly and this aids the accuracy of the settings. For example, if a change in pressure from 1001bus to 401bs is required by an operator, the controller will cause a jump to a value around 201bs and then slowly t ncrease tfle pressure up to the required value of around 40lbs. This arrangement overcomes stiction in the machine. It is particularly advantageous if phase advance calculations are also used by the micro-controller such that the microcontroller calculates the speed at which the pressure changes are occurring and makes appropriate adjustments.

The circuit also preferably monitors the state of the external brush head raise/lower switch and the micro-processor US can be programmed to take the state of this switch '!O account in making decisions on whether to effect curtain operations

Claims

1. A cleaning or sweeping apparatus comprising means for controlling the working pressure of a cleaning head in a cleaning machine comprising means for applying a variety of pressures to the cleaning head, means for monitoring and/or measuring the pressure applied, input means operable for an operator to select a desired pressure, comparator means for comparing the desired pressure with the measured pressure and for generating a control signal in response to the comparison result and means for applying the control signal to control the pressure applying means.

2. A cleaning or sweeping apparatus comprising: a frame; a brush assembly mounted on the frame for movement towards and away from a surface to be brushed; a biasing means acting between the frame and the brush assembly to apply to the brush assembly a bias towards the surface; means for measuring the pressure exerted by the brush assembly on the surface; and means for displaying the measured pressure.

3. Apparatus according to claim 1, wherein means are provided for input of a desired brush pressure by an operator and means are provided for displaying the input desired pressure.

4. Apparatus according to any one of claims 1 or 2, wherein said feedback means generates a control signal for the brush pressure dependent further on the operator input desired pressure and wherein comparator means are provided to compare the measured pressure to the desired pressure.

5. Apparatus according to claim 3, wherein said feedback means generates a control signal for the brush pressure dependent further on the operator input desired pressure and wherein comparator means are provided to compare the measured pressure to the desired pressure.

6. A sweeping or cleaning apparatus comprising: a frame; a brush assembly mounted on the frame; means for moving the brush assembly towards and away from a surface to be cleaned; biasing means acting between the frame and the brush assembly to apply to the brush assembly a selectable bias towards the surface; means for monitoring and/or measuring the applied working pressure; means for displaying an indication of the measured working pressure; means for operator entry of a desired working pressure for the brush assembly.

7. Apparatus according to claim 6 comprising comparator means for comparing the operator input pressure to the measured pressure and for generating a control signal in response to the difference between the desired pressure and the measured pressure and means for applying the control signal to the pressure applying means.

8. Apparatus according to claim 7, wherein the comparator is comprised of an electronic processor.

9. Apparatus according to any preceding claim, wherein the displaying means is adapted to display a digital value of the applied pressure.

10. Apparatus according to any preceding claim, wherein the pressure measuring means comprises a strain gauge.

11. Apparatus according to any one of claims 1 to 8, wherein the pressure measuring means comprises a pressure transducer.

12. Apparatus according to any one of claims 1 to 9, wherein the pressure measuring means comprises a piezoelectric sensor.

13. Apparatus according to any one of the preceding claims, wherein the brush pressure applied to the surface to be cleaned is adjustable by the operator.

14. Apparatus according to claim 13 comprising a rocker switch having a first position for increasing brush pressure and second opposite for decreasing pressure and means for biasing the rocker switch to an intermediate off position.

15. Apparatus for controlling brush head pressure in a cleaning or sweeping machine, the apparatus comprising: analogue to digital conversion means for converting input signals representing respectively a measured brush pressure and an operator chosen brush pressure; storage means for predetermined system parameters; computing means programmed to compare the two input signals and to generate a control signal in response to the comparison and the predetermined system parameters.

16. Apparatus according to claim 14 comprising means for sensing a state of a power supply source for the cleaning or sweeping apparatus and means for generating a signal for inhibiting brush operation when the battery state is below a preset value.

17. Apparatus according to claim 15 or 16 comprising memory means for recording an accumulation of the total usage time of the power source and to generate a signal to inhibit brush operation when the usage time exceeds a preset value.

18. Apparatus according to any one of the preceding claims comprising means to inhibit operator input brush pressure changes when the cleaning apparatus is traversing a surface to be cleaned.

19. Apparatus substantially as hereinbefore described and with reference to the figures of the accompanying drawings.