KR100467184B1 - Volume compensating pressure regulated flow control dispensing system - Google Patents

Abstract

The system of the present invention provides continuous compensation of the dispensing volume in the pressure regulating flow control system to compensate for viscosity changes and part wear of the material. Predetermined values are preset for the two counters. The first counter is decremented by the pulses from the flow meter at the outlet of the system and the second counter is decremented according to the input command. When the first counter reaches zero, the size of the second counter is checked and the gain increases and decreases accordingly.

Description

VOLUME COMPENSATING PRESSURE REGULATED FLOW CONTROL DISPENSING SYSTEM}

This application is a continuation of some of the US patent application Ser. No. 60 / 004,204, filed on September 22, 1995.

Pressure regulated flow control distribution systems have been in use for many years. However, such systems are known to be less accurate when changes in the wear of system components or the viscosity of the material itself occur.

Typically, such a system is used in robots capable of applying adhesive beads or the like, for example, around the windshield of a vehicle. Such modifications have been carried out in the past, for example distributing one completed bead on the basis of one robot cycle around the windshield of the vehicle.

Since the conditions can be changed rapidly, the present invention aims to provide a system that provides automatic volume compensation in real time to compensate for changes in such a system.

Another object of the present invention is to provide a system that can be easily implemented and uses hardware already installed in the base system.

The invention further includes a flow meter, such as a gain block and a gear meter, that multiplies the set point of the controller by the factor K. Gain blocks and other data processing functions are implemented as software on the associated controller.

Reward The switch is started by setting two counters with fixed values. The first counter is decremented by each pulse from the flowmeter and the second counter is also decremented at periodic intervals by an amount proportional to the setpoint command from other equipment (such as the robot controller).

When the first counter reaches zero to indicate that the preset fixed value has been dispensed, the contents of the second counter are compared to zero. If the size of the second counter is greater than zero, the gain is increased by a small fixed value. If the size of the second counter is less than zero, the gain is reduced by the same small fixed value. These both counters are reset and the process is repeated.

The gain factor K starts from the value 1 and can vary between the maximum and the minimum (eg 0.5 to 1.5). The sample volume is set small enough to force various adjustments along the course of the total dispensing cycle (such as windshield described above). No operator input is required for the operation of this compensator.

Also, taking the preferred embodiment as an example, each counter is initially loaded with 64 counts. The gain K is increased or decreased in 0.01 increments, and when a limit of 0.5 or 1.5 is reached a warning is given to the operator to suggest that the operator check the normal operation of the device and consider recalibration.

The above and other objects and advantages of the present invention will be fully understood from the following description in conjunction with the accompanying drawings. In the drawings, the same or similar parts are denoted by the same reference numerals.

The system 10 of the present invention is intended to be used with a representative pressure regulating flow device as shown in block 12, outlined by dashed lines. The fluid outlet of the device is provided with a flow meter 14 which sends a pulse signal to the first counter 16. For example, the flow meter can provide an output pulse each time 0.1914 cc of fluid is dispensed and this pulse is decremented at the first counter 16.

The first counter 16 is set simultaneously with the second counter 18 which is decremented when there is an input from the command input 28 via the clock 26. When the first counter 16 reaches zero, the comparator 20 confirms the size of the second counter 18. If the size of the second counter 18 is greater than zero, the gain in block 24 is increased by a small fixed value (0.01 in the preferred embodiment), while if the second counter is less than zero the gain is reduced by that amount.

The gain in block 24 is allowed a maximum of 1.5 and a minimum of 0.5 in the preferred embodiment, where an alert or warning may be generated to inform the operator that no further changes occur and that the system should be alerted.

Various changes and modifications to the distribution system can be made within the spirit and scope of the present invention as set forth in the claims below.

According to the present invention, a system is provided for providing automatic volume compensation in real time to compensate for changes in the system.

1 is a block diagram illustrating the invention.

<Explanation of symbols for the main parts of the drawings>

10: system

14: flow meter

16: first counter

18: second counter

30: comparator

Claims (10)

A method for compensating for a change in a fluid dispensing system comprising an input command, a gain block with a loop gain, and a flow meter measuring the actual system output and providing an output pulse for each unit volume dispensed, Providing a first and a second counter and loading a predetermined volume into each counter, Reducing the first counter by each pulse from the flow meter; Periodically decreasing the second counter by an amount corresponding to the flow rate calculated from the input command; Comparing the counters when the first counter reaches zero; Incrementing the gain block if the size of the second counter is greater than zero; If the second register size is less than zero, reducing the gain block. The method of claim 1, wherein the gain block is increased by a fixed value. The method of claim 1 wherein the reduction of these blocks is by a fixed value. 2. The method of claim 1 wherein the loop gain has a maximum and a minimum. 5. The method of claim 4, wherein a warning is generated when one of the maximum and minimum values is reached. A method for compensating for a change in a fluid dispensing system comprising an input command, a gain block having a loop gain, and a flow meter measuring the actual system output and providing a signal corresponding to the dispensed volume, Comparing the input command with the volume signal when a predetermined amount of material is dispensed; Increasing the gain block if the difference between the input command and the volume signal is greater than zero; Reducing the gain block if the difference between the input command and the volume signal is less than zero. 7. The method of claim 6, wherein the gain block is increased by a fixed value. 7. The method of claim 6 wherein the reduction of these blocks is by a fixed value. 7. The method of claim 6 wherein the loop gain has a maximum and a minimum. 10. The method of claim 9, wherein a warning is generated when one of the maximum and minimum values is reached.