Vacuum cup control apparatus

• US 5,201,560 A
• Filed: 09/09/1991
• Issued: 04/13/1993
• Est. Priority Date: 01/24/1991
• Status: Expired due to Term

• Current Assignee: Norgren Automotive Incorporated (IMI PLC)
• Original Assignee: John A. Blatt
• Inventors: Golden, Michael J.
• Primary Examiner(s): CHERRY, JOHNNY DAN
• Application Number:
  US07/756,497
• Time in Patent Office: 582 Days
• Field of Search: 294/64.1, 294/64.2, 294/65, 294/907, 137/487.5, 137/502, 137/557, 137/560, 271/96, 271/98, 271/108, 307/118, 414/627, 414/737, 414/752, 417/182, 417/185-193
• US Class Current: 294/64.2
• CPC Class Codes: B65G 47/91 incorporating pneumatic, e.g. suction, grippers
• CPC Class Codes: B65G 47/917 control arrangements
• CPC Class Codes: Y10T 137/7761 Electrically actuated valve

Abstract

A vacuum cup control apparatus for applying and releasing vacuum in a vacuum cup includes a venturi passage for inducing a vacuum within the vacuum cup upon the flow of pressurized air therethrough. Another air flow passage extends through the housing for injecting a flow of air under pressure to the vacuum cup to relieve the vacuum therein. A sensor senses the vacuum level attained in the vacuum cup. A feedback signal is sent by the control apparatus to the external controller as an indication that a predetermined, selectable vacuum level has been achieved. The control apparatus is responsive to the sensor and signals from an external controller for applying vacuum to the vacuum cup until a predetermined vacuum level is attained in the vacuum cup. After the initial application of vacuum and prior to the injection of air under pressure to the vacuum cup, if the vacuum level within the vacuum cup decreases below the predetermined set level, the control apparatus will automatically reapply vacuum until the predetermined vacuum level is reached. A plurality of comparators, each provided with offset reference signal inputs, are responsive to the output of the sensor and generate a plurality of discrete vacuum select levels. A selector switch selects one of the comparator outputs to specify a predetermined vacuum level in the vacuum cup.

Claims

1. A vacuum control apparatus for applying a flow or pressurized air through a venturi to create a vacuum in a vacuum responsive device, the vacuum control apparatus comprising:

sensor means, disposed in fluid flow communication with a fluid flow conduit connected to the vacuum responsive device, for sensing the vacuum level applied to the vacuum responsive device and providing an output signal proportional thereto;

connector means, for receiving electrical signals specifying the application and release of vacuum in the vacuum responsive device;

first valve means for controlling the flow of pressurized air to the venturi;

control means, responsive to the sensor means and the connector means, for controlling the selective application of a predetermined vacuum pressure to the vacuum responsive device and the re-application of vacuum to the vacuum responsive device in the event of a decrease of vacuum below a predetermined level after vacuum is applied to the vacuum responsive device, the control means including;

comparator means, responsive to the sensor means output signal and a plurality of discrete, different reference signals, for comparing the sensor means output signal with each of the reference signal and generating one of a plurality of discrete outputs, each corresponding to a different vacuum level output;

means for selecting one of the comparator means outputs as an output specifying a predetermined amount of vacuum to the vacuum responsive device; and

first driver means, responsive to the output of the selecting means, for energizing the first valve means to supply pressurized air to the venturi to supply a specified vacuum level to the vacuum responsive device when the output signal of the sensor means indicates a vacuum level in the vacuum responsive device less than the selected vacuum level.

2. The vacuum control apparatus of claim 1 wherein the comparator means comprises:

a plurality of individual comparators;

the output signal of the sensor means being connected as an input to each of the plurality of comparators; and

means for varying the magnitude of the reference signal applied to each of the plurality of comparators by a predetermined amount from the magnitude of the reference signal applied to a preceding one of the plurality of comparators.

3. The vacuum control apparatus of claim 2 wherein the means for varying the magnitude of the reference signal comprises:

a first reference signal connected to the input of a first one of the plurality of comparators;

a plurality of serially connected resistors connected to the first reference signal; and

the juncture of each of the serially connected resistors being respectively connected as an input to each of the other of the plurality of comparators and acting as a reference signal input to each of the other of the plurality of comparators.

4. The vacuum control apparatus of claim 3 wherein:

each of the serially connected resistors has the same resistance so as to incrementally offset the reference signal input to each of the other of the plurality of comparators by an incremental amount.

5. The vacuum control apparatus of claim 1 wherein the selecting means comprises:

switch means switchable between a plurality of discrete positions, each position connected to one of the plurality of comparator outputs.

6. The vacuum control apparatus of claim 1 wherein the control means further comprises:

hysteresis control means, connected between the output of the comparator means and the reference signals, for varying the magnitude of the reference signals by a predetermined amount from the initial magnitude of the reference signals after an output signal is generated by the comparator means until the vacuum level sensed by the sensor means falls below the predetermined level set by the hysteresis control means.

7. The vacuum control apparatus of claim 1 further comprising:

second valve means connected in fluid flow communication with the vacuum responsive device for supplying air under pressure to the vacuum responsive device;

the control means further comprising;

second driver means for energizing the second valve means to apply air under pressure to the vacuum responsive device; and

the second driver means also being separately responsive to an electrical signal from the connector means for activating the second driver means.

8. The vacuum control apparatus of claim 1 wherein the control means further comprises:

second means for selecting one of the plurality of comparator outputs as a feedback signal indicating the vacuum level in the vacuum line connected to the vacuum responsive device, the output of the second selecting means being connected to the connector means.

9. A vacuum control apparatus for applying a flow of pressurized air through a venturi to create a vacuum in a vacuum responsive device, the vacuum control apparatus comprising:

sensor means, disposed in fluid flow communication with a fluid flow line connected to the vacuum responsive device, for sensing the vacuum applied to the vacuum responsive device and providing an output signal proportional thereto;

connector means, for receiving electrical signals specifying the application and release of vacuum in the vacuum responsive device;

first valve means for controlling the flow of pressurized air to the venturi;

second valve means connected in fluid flow communication with the vacuum responsive device for supplying air under pressure to the vacuum responsive device; and

control means, responsive to the sensor means and the connector means, for controlling the selective application of a predetermined vacuum pressure to the vacuum responsive device and the re-application of vacuum to the vacuum responsive device in the event of a decrease of vacuum below a predetermined level after vacuum is applied to the vacuum responsive device, the control means including;

comparator means responsive to the sensor means output signal and a plurality of reference signals, for comparing the sensor means output signal with the reference signals and generating one of a plurality of discrete outputs each corresponding to a different vacuum level output sensed by the sensor means, the comparator means including;

a plurality of individual comparators;

the output signal of the sensor means being connected as an input to each of the plurality of comparators; and

means for varying the magnitude of the reference signal applied to each of the plurality of comparators by a predetermined amount from the magnitude of the reference signal applied to a preceding one of the plurality of comparators;

first means for selecting one of the comparators outputs as an output specifying a predetermined amount of vacuum in the vacuum responsive device, the first selecting means including;

switch means switchable between a plurality of discrete positions, each position connected to one of the plurality of comparators outputs;

second means for selecting one of the plurality of comparator outputs as a feedback signal indicating the vacuum level in the vacuum line connected to the vacuum responsive device, the output of the second selecting means being connected to the connector means;

first drive means, responsive to the output of the first selecting means, for energizing the first valve means to supply pressurized air to the venturi to supply a specified vacuum level to the vacuum responsive device when the output signal of the sensor means indicates a vacuum level in the vacuum responsive device less than the selected vacuum level; and

second driver means for energizing the second valve means to supply air under pressure to the vacuum responsive device, the second driver means also being separately responsive to an electrical signal from the connector for activating the second driver means.