Vacuum cup control apparatus

• US 5,188,411 A
• Filed: 01/24/1991
• Issued: 02/23/1993
• 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:
  US07/645,135
• Time in Patent Office: 761 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, 417/186-193
• 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: Y10S 294/907 Sensor controlled device
• CPC Class Codes: Y10T 137/7761 Electrically actuated valve

Abstract

A vacuum cup control apparatus for applying and releasing vacuum in a vacuum cup engaging a workpiece includes a housing having a venturi passage for inducing a vacuum within the vacuum cup upon the flow of air through the venturi passage. A one-way check valve in the passage seals the vacuum in the vacuum cup upon cessation of air flow through the venturi passage. Another air flow passage extends through the housing to a control port on the housing for injecting a flow of air under pressure to the vacuum cup to relieve the vacuum therein. A sensor mounted in the housing 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 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. The control apparatus also injects air under pressure to the vacuum cup to relieve the vacuum in response to a signal from the external controller. 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 reapply vacuum until the predetermined vacuum level is reached.

Claims

1. A vacuum cup control apparatus for applying and releasing vacuum to a vacuum cup engaging a workpiece, the vacuum cup control apparatus comprising:

a housing;

a first flow passage extending through the housing between a first inlet connected to a source of air under pressure and an outlet vented to atmosphere;

venturi means including a throat section disposed in the first passage for producing a subatmospheric pressure in the throat section on the flow of air through the first passage;

a control port in the housing opening at one end in fluid flow communication with the vacuum cup;

a second flow passage formed in the housing and extending from the first flow passage to the control port;

a one-way valve disposed in the second passage and allowing flow in one direction from the control port through the second passage to the first passage;

a third flow passage in the housing connected to a source of air under pressure and to the control port for supplying air under pressure to the vacuum cup to release vacuum in the vacuum cup;

sensor means, mounted in the housing and disposed in fluid flow communication with the control port, for sensing the vacuum pressure at the control port in the housing;

connector means for receiving electrical signals specifying the application and release of vacuum in the vacuum cup; and

control means, mounted in the housing and responsive to the sensor means and the connector means, for controlling the selective application of vacuum to the vacuum cup, the application of pressure air to the vacuum cup and the reapplication of vacuum to the vacuum cup in the event of a decrease in vacuum in the vacuum cup below a predetermined level after vacuum is applied to the vacuum cup and prior to the application of pressurized air to the vacuum cup, the control means including;

valve means for controlling the flow of air to the first and third passages in the housing;

first comparator means, responsive to the sensor means and a first reference signal specifying a predetermined vacuum level connected to a reference signal input of the first comparator means, for comparing the output of the sensor means with the first reference signal;

the first comparator means generating an output signal when the vacuum level sensed by the sensor means reaches a predetermined level established by the first reference signal;

first driver means for energizing the valve means to apply vacuum to the vacuum cup;

first logic means, responsive to the first comparator means and the connector means, for activating the first driver means to apply vacuum to the vacuum cup and to de-activate the first driver means when a predetermined vacuum is present in the vacuum cup; and

hysteresis control means, connected between the output and the reference signal input of the first comparator means, for lowering the first reference signal input to the first comparator means to a predetermined level less than the first reference signal after an output signal is generated by the first comparator means until the vacuum level sensed by the sensor means falls blow the predetermined level set by the hysteresis control means.

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

second comparator means, responsive to a second reference signal and the output of the sensor means, for generating an output when the output from the sensor means exceeds the second reference signal;

second driver means for energizing the value means to apply air under pressure to the vacuum cup; and

second logic means, responsive to the second comparator means and the connector means, for activating the valve means to apply air under pressure to the vacuum cup to release vacuum therefrom.

3. The vacuum cup control apparatus of claim 2 wherein:

the second comparator means, in response to the sensor means, regenerates an output when the output of the sensor means exceeds the second reference signal at any time after the second logic means has initially activated the value means to apply air under pressure to the vacuum cup, the second logic means reactivating the valve means to reapply air under pressure to the vacuum cup to release the vacuum therefrom.

4. The vacuum cup control apparatus of claim 1 wherein the control means comprises:

another comparator means, responsive to a reference signal and the output of the sensor means, for generating an electrical signal indicative of a predetermined vacuum level in the vacuum cup; and

another driver means, connected to the another comparator means and the connector means, for supplying the electrical signal from the another comparator means to the connector means.

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

a first valve connected between the source of air under pressure and the first inlet in the housing for supplying, when energized, air under pressure to the first flow passage; and

a second valve connected between the source of air under pressure and the third flow passage in the housing for supplying, when energized, air under pressure to the third flow passage.

6. A vacuum cup control apparatus for applying and releasing vacuum to a vacuum cup engaging a workpiece, the vacuum cup control apparatus comprising:

a housing;

a first flow passage extending through the housing between a first inlet connected to a source of air under pressure and an outlet vented to atmosphere;

venturi means including a throat section disposed in the first passage for producing a subatmospheric pressure in the throat section on the flow of air through the first passage;

a control port in the housing opening at one end in fluid flow communication with the vacuum cup;

a second flow passage formed in the housing and extending from the first flow passage to the control port;

a one-way valve means disposed in the second passage allowing flow in one direction from the control port through the second passage to the first passage;

a third flow passage in the housing connected to a source of air under pressure and to the control port for supplying air under pressure to the vacuum cup to release vacuum in the vacuum cup;

sensor means, mounted in the housing and disposed in fluid flow communication with the control port, for sensing the vacuum pressure at the control port in the housing;

connector means for receiving electrical signals specifying the application and release of vacuum in the vacuum cup;

valve means for controlling the flow of air to the first and third passages in the housing;

first comparator means, responsive to the sensor means and first reference signal specifying a predetermined vacuum level connected to a reference signal input of the first comparator means, for comparing the output of the sensor means with the first reference signal;

the first comparator means generating an output signal when the vacuum level sensed by the sensor means reaches a predetermined level established by the first reference signal;

first driver means for energizing the valve means to apply vacuum to the vacuum cup;

first logic means, responsive to the first comparator means and the connector means, for activating the first driver means to apply vacuum to the vacuum cup and to de-activate the first driver means when a predetermined vacuum is present in the vacuum cup;

second comparator means, responsive to a second reference signal and the output of the sensor means, for generating an output when the output from the sensor means exceeds the second reference signal;

second driver means for energizing the valve means to apply air under pressure to the vacuum cup;

second logic means, responsive to the second comparator means and the connector means, for activating the valve means to apply air under pressure to the vacuum cup to release vacuum therefrom;

third comparator means, responsive to a reference signal and the output of the sensor means, for generating an electrical signal indicative of a predetermined vacuum level in the vacuum cup; and

third driver means, connected to the third comparator means and the connector means, for supplying the electrical signal from the third comparator means to the connector means.

7. The vacuum cup control apparatus of claim 6 wherein:

the first, second and third driver means comprise a relay having an energizable coil controlling a first switchable element.

8. The vacuum cup control apparatus of claim 6 further including:

hysteresis control means, connected between the output and the reference signal input of the first comparator means, for lowering the first reference signal input to the first comparator means to a predetermined level less than the first reference signal after an output signal is generated by the first comparator means until the vacuum level sensed by the sensor means falls below the predetermined level set by the hysteresis control means.