GB2150981A

GB2150981A - Apparatus and method for pumping a fluid

Info

Publication number: GB2150981A
Application number: GB08329966A
Authority: GB
Inventors: Robert Graham Malcolm Low
Original assignee: VS ENG Ltd
Current assignee: VS ENG Ltd
Priority date: 1983-11-10
Filing date: 1983-11-10
Publication date: 1985-07-10
Also published as: GB8329966D0

Abstract

Apparatus for pumping a fluid (4) from a reservoir (3) comprising a pipeline (1), a first pumpe (7) arranged near an entrance of the pipeline for pumping fluid from the reservoir along the pipeline and a second pump (13) arranged near an exit (11) of the pipeline and operable to regulate flow of fluid out of the exit, the first pump (7) being adapted to develop fluid pressure in that portion of the pipe which is between the said two pumps and the second pump being adapted to pump fluid at a given rate from that portion so as to reduce or tend to reduce the pressure. The second pump (13) may be of the gear type driven by a stepper motor (15) controlled by a micro-computer system (17). <IMAGE>

Description

SPECIFICATION Apparatus and method for pumping a fluid The present invention relates to an apparatus and method for pumping a fluid.

With known pumping apparatus and methods, a fluid is pumped along pipework to exit at an orifice remote from the pump. Flow of the fluid, including initiation of the flow and shut-off of the flow at the orifice, is often rendered inaccurate and unpredictable due to the effect of fluid compressibility, variations in viscosity, elastic expansion of the pipework or a combination of any of those factors.

When applying adhesive from a reservoir thereof to a workpiece as a thin, elongate bead from a delivery pipe it is desirable for the thickness of the bead to be substantially uniform. With known adhesive delivery systems, the presence of the above-stated factors tends to result in a non-uniform and sometimes discontinuous bead. In particular, when the pump in a known system has been turned off, the adhesive still continues to ooze out of the nozzle of the delivery pipe since the adhesive was compressed in the pipe when it was being pumped therealong.

The present invention provides apparatus for pumping a fluid from a reservoir comprising a pipeline, a first pump means arranged near an entrance of the pipeline for pumping fluid from a reservoir along the pipeline and a second pump means arranged near an exit of the pipeline and operable to regulate flow of fluid out of the exit.

The present invention further provides a method of pumping a fluid from a reservoir comprising the steps of:- pumping fluid from the reservoir into a pipeline through an entrance thereof by first pump means arranged near the entrance; developing fluid pressure in the pipeline; and pumping a regulated flow of fluid at a given rate from the pipeline through an exit thereof by a second pump means arranged near the exit so as to reduce or tend to reduce the fluid pressure.

An embodiment of the present invention will now be described by way of example only with reference to the accompanying drawing, in which: Figure 1 is a schematic illustration of an apparatus for pumping a fluid from a reservoir.

Referring to Fig. 1, a pipeline 1 is in communication with a reservoir 3 containing a fluid 5 to be pumped along the pipeline 1. A primary pump 7 is disposed at or near that end 9 of the pipeline 1 which communicates with the reservoir 3. The primary pump 7 preferably includes a hydraulically operated ram which can move at a variable controllable velocity thereby to produce a variable particular flow rate of fluid 5 from the reservoir 3.

The primary pump 7 is controlled by a primary pump control means 8.

The pipeline 1 may be rigid or flexible according to the particular application.

At or near an end 11 of the pipeline 1 which is remote from the reservoir 3 is a metering or regulating pump 1 3. The metering pump 1 3 is operable to regulate the flow of fluid 5 out of the end 11. Preferably the metering pump is disposed on the pipeline at a position immediately preceding the end 11 which constitutes a nozzle for the pipeline 1.

The metering pump 1 3 may be a gear pump which is driven by a stepper motor 1 5. A micro-computer system 1 7 controls the speed of rotation of the gear pump by varying the frequency of driving puises sent to the stepper motor 1 5.

Optionally, a cut-off valve 1 9 is provided at the nozzle 11 of the pipeline 1 to break the flow of the fluid 5, the valve 1 9 being operable to be open or closed in synchronism with the switching ON or OFF respectively of the metering pump 1 3.

A programmable logic control means 21 can control the flow rates of both the primary pump 7 and the metering pump 1 3 by sending electrical signals to the primary pump control means 8 and to the micro-computer system 17.

The primary pump 7 provides the power to propel the fluid 5 along the pipeline 1 while the nozzle exit flow rate is accurately regulated by the fine metering pump 1 3. Accurate flow control by the primary pump 7 is not required and it need only provide coarse metering of the flow of fluid 5. The metering pump 1 3 is fed from the pipeline 1. The primary pump 7 develops fluid pressure in that portion of the pipeline 1 which is between the pumps 7, 1 3 and the metering pump 1 3 pumps fluid 5 from that portion at a desired rate so as to reduce or tend to reduce that pressure.The metering pump 1 3 is adapted to suit the particular characteristics of the fluid 5 to be pumped and is capable of providing a variable flow rate by varying the speed of displacement of the pump drive means. The flow of fluid 5 from the nozzle 11 is interrupted by switching OFF the metering pump 13.

The present invention has particular application in the delivery of a viscous, compressible liquid, such as an adhesive, from a reservoir to a point of application. The preferred apparatus can form a thin uniform elongate bead of adhesive with substantially no thickness variations occurring in the bead. The apparatus may be used in particular in conjunction with a robot for use in a vehicle assembly production line. The preferred embodiment of the present invention substantially overcomes the problems stated above which are encountered with known systems.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Apparatus and method for pumping a fluid The present invention relates to an apparatus and method for pumping a fluid. With known pumping apparatus and methods, a fluid is pumped along pipework to exit at an orifice remote from the pump. Flow of the fluid, including initiation of the flow and shut-off of the flow at the orifice, is often rendered inaccurate and unpredictable due to the effect of fluid compressibility, variations in viscosity, elastic expansion of the pipework or a combination of any of those factors. When applying adhesive from a reservoir thereof to a workpiece as a thin, elongate bead from a delivery pipe it is desirable for the thickness of the bead to be substantially uniform. With known adhesive delivery systems, the presence of the above-stated factors tends to result in a non-uniform and sometimes discontinuous bead. In particular, when the pump in a known system has been turned off, the adhesive still continues to ooze out of the nozzle of the delivery pipe since the adhesive was compressed in the pipe when it was being pumped therealong. The present invention provides apparatus for pumping a fluid from a reservoir comprising a pipeline, a first pump means arranged near an entrance of the pipeline for pumping fluid from a reservoir along the pipeline and a second pump means arranged near an exit of the pipeline and operable to regulate flow of fluid out of the exit. The present invention further provides a method of pumping a fluid from a reservoir comprising the steps of:- pumping fluid from the reservoir into a pipeline through an entrance thereof by first pump means arranged near the entrance; developing fluid pressure in the pipeline; and pumping a regulated flow of fluid at a given rate from the pipeline through an exit thereof by a second pump means arranged near the exit so as to reduce or tend to reduce the fluid pressure. An embodiment of the present invention will now be described by way of example only with reference to the accompanying drawing, in which: Figure 1 is a schematic illustration of an apparatus for pumping a fluid from a reservoir. Referring to Fig. 1, a pipeline 1 is in communication with a reservoir 3 containing a fluid 5 to be pumped along the pipeline 1. A primary pump 7 is disposed at or near that end 9 of the pipeline 1 which communicates with the reservoir 3. The primary pump 7 preferably includes a hydraulically operated ram which can move at a variable controllable velocity thereby to produce a variable particular flow rate of fluid 5 from the reservoir 3. The primary pump 7 is controlled by a primary pump control means 8. The pipeline 1 may be rigid or flexible according to the particular application. At or near an end 11 of the pipeline 1 which is remote from the reservoir 3 is a metering or regulating pump 1 3. The metering pump 1 3 is operable to regulate the flow of fluid 5 out of the end 11. Preferably the metering pump is disposed on the pipeline at a position immediately preceding the end 11 which constitutes a nozzle for the pipeline 1. The metering pump 1 3 may be a gear pump which is driven by a stepper motor 1 5. A micro-computer system 1 7 controls the speed of rotation of the gear pump by varying the frequency of driving puises sent to the stepper motor 1 5. Optionally, a cut-off valve 1 9 is provided at the nozzle 11 of the pipeline 1 to break the flow of the fluid 5, the valve 1 9 being operable to be open or closed in synchronism with the switching ON or OFF respectively of the metering pump 1 3. A programmable logic control means 21 can control the flow rates of both the primary pump 7 and the metering pump 1 3 by sending electrical signals to the primary pump control means 8 and to the micro-computer system 17. The primary pump 7 provides the power to propel the fluid 5 along the pipeline 1 while the nozzle exit flow rate is accurately regulated by the fine metering pump 1 3. Accurate flow control by the primary pump 7 is not required and it need only provide coarse metering of the flow of fluid 5. The metering pump 1 3 is fed from the pipeline 1. The primary pump 7 develops fluid pressure in that portion of the pipeline 1 which is between the pumps 7, 1 3 and the metering pump 1 3 pumps fluid 5 from that portion at a desired rate so as to reduce or tend to reduce that pressure.The metering pump 1 3 is adapted to suit the particular characteristics of the fluid 5 to be pumped and is capable of providing a variable flow rate by varying the speed of displacement of the pump drive means. The flow of fluid 5 from the nozzle 11 is interrupted by switching OFF the metering pump 13. The present invention has particular application in the delivery of a viscous, compressible liquid, such as an adhesive, from a reservoir to a point of application. The preferred apparatus can form a thin uniform elongate bead of adhesive with substantially no thickness variations occurring in the bead. The apparatus may be used in particular in conjunction with a robot for use in a vehicle assembly production line. The preferred embodiment of the present invention substantially overcomes the problems stated above which are encountered with known systems. CLAIMS

1. Apparatus for pumping a fluid from a reservoir comprising a pipeline, a first pump means arranged near an entrance of the pipeline for pumping fluid from a reservoir along the pipeline and a second pump means arranged near an exit of the pipeline and operable to regulate flow of fluid out of the exit.

2. Apparatus according to Claim 1 wherein the first pump means is adapted to develop fluid pressure in that portion of the pipe which is between the said two pump means and the second pump means is adapted to pump fluid at a given rate from that portion so as to reduce or tend to reduce the pressure.

3. Apparatus according to Claim 1 or Claim 2 further comprising means for controlling the respective flow rate of fluid through both the first and second pump means.

4. Apparatus according to any foregoing claim further comprising a cut-off valve disposed at the exit and operable to be open or closed in synchronism with the switching ON or OFF respectively of the second pump means.

5. Apparatus according to any foregoing claim wherein the first pump means includes a hydraulic ram.

6. Apparatus according to any foregoing claim wherein the second pump means is a gear pump.

7. Apparatus for pumping a fluid from a reservoir substantially as hereinbefore described with reference to and as illustrated in Fig. 1.

8. A method of pumping a fluid from a reservoir comprising the steps of:- pumping fluid from the reservoir into a pipeline through an entrance thereof by first pump means arranged near the entrance; developing fluid pressure in the pipeline; and pumping a regulated flow of fluid at a given rate from the pipeline through an exit thereof by a second pump means arranged near the exit so as to reduce or tend to reduce the fluid pressure.

9. A method according to Claim 8 wherein the first and second pump means are controlled by a control means so as to regulate the respective rate of fluid flow through each pump means.

10. A method according to Claim 8 or Claim 9 wherein fluid flow out of the pipeline is controlled by a cut-off valve which is disposed at the exit and is operable to be open or closed in synchronism with the switching ON or OFF respectively of the second pump means.

11. A method of pumping a fluid from a reservoir substantially as hereinbefore described with reference to and as illustrated in Fig. 1.