NL1043255B1 - Service vehicle with pressure control - Google Patents

Abstract

A service tooi (10) comprises: a pump (14) for providing pressurized liquid to a hose (12) having a nozzle (19) at its free end; a motor (15) for driving the pump (14); a control device (20) for controlling the motor (15); a pressure sensor (30) for sensing liquid pressure. The control device (20) receives a sensor output signal from the pressure sensor (30), and is adapted to control the motor (15) in such manner that liquid pressure remains at a substantially constant level. For keeping the liquid pressure constant at the nozzle, liquid pressure can be sensed at the pump or at the entrance side of the hose. TO PUBLISH WITH ABSTRACT: figure 2 1043255

Description

ref: P 2019 NL 014 TITLE: Service vehicle with pressure control

FIELD OF THE INVENTION The present invention relates in general to a service vehicle, typically a van or truck, for performing cleaning operations by means of pressurized water, By way of example, the water is sprayed through a nozzle to clean the exterior walls of buildings, or to clean the interior walls of pipes.

BACKGROUND OF THE INVENTION A vehicle of the type indicated comprises cleaning apparatus, which includes a water supply, hoses and nozzles for transporting and applying the pressurized water, and a pump for pressurizing the water and feeding the pressurized water through the hoses.

Said pump is a motor-driven pump which will be in operation, conlinuously or intermittently, for as long as the cleaning operation takes. The motor typically involves a combustion engine, which is operative continuously as long as the pump is operative, For proper operation, it is required that the walter pressure at the distal end of the hose, i.e. at the nozzle, has a certain operational value. The pump should be able to supply the water at this pressure, taking into account the rate of water flow in the hose. lt should be taken into account that during use, the user may vary the water flow. It should further be taken into account that users should be able to change nozzies.

In current apparatus, the pump power, Le. motor rpm, is set at such high value that the water pressure at the position of the nozzle guaranteed at all times is higher than the required operational pressure. The nozzle acts as a flow-limiter, having a maximal flow rate that can pass, and the pump setting results in a water supply higher than said maximal flow rate. The excess water rate is discarded.

Producing an excess water rate means that something has to be done with the excess amount of water. The excess amount of water can be fed back to the water supply of the apparatus, but this at least requires feedback conduits, and consumes further power from said or other pump. In any case, producing an excess water rate involves an excess consumption of energy.

| SUMMARY OF THE INVENTION It is a general objective of the present invention to eliminate or at lsast reduce this problem, Particularly, # is an objective of the invention to effect a reduction of energy consumption. According to an aspect of the present invention, a pressure sensor is used to sense the actual water pressure, and the sensor output signal is supplied as input Io a control device controlling the motor power.

The pressure sensor may be located in proximity of the nozzle, to measure the actual pressure at the position of the nozzle. However, in practice, the pressure drop over the hose can either be estimated or determined experimentally, even as a function of water flow rate, so that conversely it is possible to take this expected pressure drop into account when controlling pump pressure. Therefore, in a more preferred embodiment, the pressure sensor may be located at the entrance of the hose or at the output of the pump, or may be integrated within the pump.

According to a further aspedt of the invention, a controllable electric motor is used for powering the pump. The electric motor may obtain its power from a generator, but preferably the electric motor obtains its power from a battery pack, if is relatively easy to vary motor power in the case of an electric motor. tis further relatively easy to quickly effect variations in motor power to adapt for variations in water consumption , such that the aclual water pressure remains substantially constant.

BRIEF DESCRIPTION OF THE DRAWINGS These and other aspects, features and advantages of the present invention will be further explained by the following description of one or mors preferred embodimants with reference to the drawings, in which same reference numerals indicate same or similar parts, and in which: Figure 1 is a diagram schematically showing a service vehicle; Figure 2 is a schematic block diagram, showing control of the pump motor.

DETAILED DESCRIPTION OF THE INVENTION Figure 1 is a diagram schematically showing a service vehicle 1 standing on a bottom 2. The vehicle 1 has a cabin 3 in which a cleaning apparatus 10 is arranged. The cleaning apparatus 10 may be of the type having a reel 11 carrying a wound hose 12 for providing pressurized liquid, typically water. At its remote free end, the hose 12 has a nozzle 18. A water reservoir is indicated at 13. Reference numeral 14 indicates a pump that pressurizes water from the reservoir 13 and supplies i to the hase 12. The pump is driven by a motor 15. i is noted that the precise nature and design of the pump is not relevant for understanding the present invention, and will therefore not be discussed here in further detail.

ft is likewise noted that the precise nature and design of the motor is not relevant for understanding the present invention, and will therefore not be discussed here in further detail. However, it is preferred that the motor 15 is an electric motor, ft is further noted that although the cleaning apparatus 10 will usually be of mobile type, as shown, that is as such not necessary for understanding and implementing the present invention.

Figure 2 is a schematic block diagram, showing the motor 15 and the pump

14. Reference numeral 20 indicates a control device for controlling the motor 15. The control device 20 may for instance comprise a microcontroller or microprocessor, as should be clear to persons skilled in the art.

Figure 2 illustrates the preferred embodiment, in which the motor 15 is an electric motor. Reference numeral 40 indicates a battery pack for supplying the motor 15 with electric power.

Reference numeral 30 indicates a pressure sensor associated in this example with the pump 14, for sensing water pressure. The pressure sensor 30 has a signal output for providing a sensor oulput signal that represents the measured pressure. The precise position of the pressure sensor 30 is not critical, and in an alternative embodiment the pressure sensor may be associated with the hose 12.

The control device 20 has a signal input 21 connected to receive the sensor output signal from the pressure sensor 30. The control device 20 is adapted to control the motor 15, typically the motor rpm, in such way that the sensor output signal as received corresponds io a target value, This target value is either stored in a memory (not shown) associated with the control device 20, or set by a user at a user input 22. If the pressure sensor 30 is mounted at the entrance side of the hose or at the pump, the target value for the sensed pressure is based on the desired pressure at the nozzle plus a correction value to take info account a pressure loss in the nozzle, which in tum may depend on the flow rate. A further sensor may be provided to sense the flow rate, but it is also possible that the flow rate is proportional to motor rpm.

In general, different types of nozzles may be used, and sach nozzle may have its own characteristics regarding input pressure and flow rate. These characteristics may be stored In a memory accessible for or associated with the control device 20.

. 4 The control device 20 may also have an input for receiving information defining the type of nozzle actually mounted. From the actual flow rate and liquid pressure, the control device 20 may find deviations caused for instance by wear of the nozzle, and may generate a warning signal to indicate that the nozzle is wearing out.

It is possible that the motor 15 is connected directly to the battery pack 40, and that the control device 20 controls the power consumption by the motor 15. The figure illustrates a situation where the control device 20 is functionally positioned between the battery pack 40 and the motor 15, so that the control device 20 controls the amount of power supplied to the motor 15.

As will be clear to a person skilled in the att, in the case of a combustion engine, engine power control and hence pump pressure control may be effected by regulating the amount of gas and air supplied to the engine.

it should be clear to a person skilled in the art that the present invention is not limited to the exemplary embodiments discussed above, but that several variations and modifications are possible within the protective scope of the invention as defined in the appending claims. For instance, two or more functions may be performed by one single entity, unit or processor. Even if certain features are recited in different dependent claims, the present invention also relates to an embodiment comprising these features in common. Even if certain features have been described in combination with each other, the present invention also relates to an embodiment in which ane or more of these features are omitied. Features which have not been explicitly described as being essential may also be omitted. Any reference signs in a claim should not be construed as limiting the scope of that claim.

in the above, the present invention has been explained with reference to block diagrams, which Hlustrate functional blocks of the device according to the present invention, it is to be understood that one or more of these functional blocks may be implemented in hardware, where the function of such functional block is performed by individual hardware components, but it is also possible that one or more of these functional blocks are implemented In software, so that the function of such functional block is performed by ons or more program lings of a computer program or a programmable device such as a microprocessor, microcontroller, digital signal processor, elo.

Claims (12)

© "CONCLUSIONS A service tool (10) comprising: a pump (14) for supplying pressurized liquid to a hose (12) having a nozzle (19) at its free end; a motor (15) for driving the pump (14); a control device (20) for controlling the motor (15); a pressure sensor (30) for sensing fluid pressure; wherein the control device (20) from the pressure sensor (30} receives a sensor output signal, and is arranged to control the motor (15) in such a way that the liquid pressure remains at a substantially constant level. A service tool according to claim 1, wherein the motor (15) comprises an electric motor. The service tool of claim 2, further comprising a battery pack (40) for providing electrical power to the electric motor (15). A service tool according to any of the preceding claims, wherein the pressure sensor (30) is associated with the pump (14) to provide a sensor output signal representative of pump output pressure. A, A service tool according to any of the preceding claims 1-3, wherein the pressure sensor (30) is associated with an input side of the hose (12) to provide a sensor output signal representative of fluid pressure at the hose entrance. A service tool according to any of the preceding claims 1-3, wherein the pressure sensor (30) is associated with an exit side of the hose (12), or with the nozzle (19), for providing a sensor output signal representative of fluid pressure. at the mouthpiece (19). Service message according to any of the preceding claims, wherein the control device (20) controls the rotational speed of the motor (15). Service tool according to any of the preceding claims, wherein the control device (20) controls the motor (15) in such a way that the sensed fluid pressure remains at a substantially constant level. go. Service tool according to any of the preceding claims 1-7, wherein the control device (20) controls the motor (15) in such a way that the fluid pressure at the nozzle (19) remains at a substantially constant level. Service tool according to any of the preceding claims, wherein the service tool (10) comprises a cleaning device (10). A service tool according to any of the preceding claims, wherein the control device (20) is configured to output a warning signal when the actual flow rate in conjunction with the actual nozzle pressure indicates nozzle wear. A service vehicle (1) comprising a cabin (3) and a service tool (10) arranged in the cabin according to any of the preceding claims.