# US 5,348,393 A · Safety guard system for food mixer

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- Number: US 5,348,393 A
- Document ID: US5348393A
- Status: Granted
- Kind: A
- Application number: 07/919,039
- Filed: 1992-07-24
- Granted: 1994-09-20
- Earliest claimed: 1992-07-24
- Assignees: Univex Corporation
- Inventors: Phillip M. Pappas, Jr.
- Web page: https://patentgrep.com/patent/US5348393A

## CPC

- B01F 27/805: wherein the stirrers or the receptacles are moved in order to bring them into operative position; Means for fixing the receptacle
- B01F 35/60: Safety arrangements
- Y10S 366/603: Animal food mixer
- B01F: MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING (mixing paints B44D3/06)
- Y10S: TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS

## Abstract

A food mixer includes a dual mount sensor arrangement which prevents operation of the mixer unless a protective safety guard is secured to the mounts. Each mount is physically spaced from each other so that a user must take extraordinary, and deliberate measures to circumvent the safety feature. The dual mount arrangement may be used in conjunction with a bowl lowering shut-off feature for disabling the mixer when the mixing bowl is lowered to a position where the user's safety is at risk.

## Claims

### Claim 1

A food mixer, comprising:
a housing;
a drive train enclosure mounted to and extending from an upper portion of the housing;
a removable bowl for holding ingredients to be blended;
a bowl support to support the removable bowl below the drive train enclosure:
a motor;
at least two mounts positioned on the housing more than a hand width apart from each other so that said two mounts cannot be contacted simultaneously by the same hand;
a detachable protective guard, positioned between the drive train enclosure and the removable bowl, the guard having a structure for blocking hand access to said bowl when supported within the bowl support, and having at least two support members each arranged to engage an associated one of said mounts such that the guard is cantilevered from said mounts over said bowl, said protective guard being capable of manual detachment from said mounts solely by manipulating the detachable guard itself;
a mixing attachment driven by said motor, said attachment extending downward from the drive train enclosure, through said protective guard, and into the removable bowl to blend the ingredients in the bowl;
at least two sensors, each sensor associated with a respective one of said at least two mounts, to detect the engagement of said support members and said mounts; and
a controller responsive to said sensors for deactivating said motor when either of said support members is disengaged from the associated one of said mounts.

### Claim 2 (depends on 1)

The mixer of claim 1 further comprising:
means for changing the relative spacing between said container and said protective guard such that with a first spacing a user is denied access to said mixing attachment; and
a third sensor to detect that said relative spacing is said first spacing; and
said controller being responsive to said third sensor for disabling said drive system unless said relative spacing is said first spacing.

### Claim 3 (depends on 2)

The mixer of claim 2 wherein said protective guard has voided portions with dimensions affording access sufficient for introducing said ingredients into said container through said guard but insufficient to permit the passage of a human hand, said relative spacing being said first spacing.

### Claim 4 (depends on 2)

The mixer of claim 2 wherein said means for changing the relative spacing to said first spacing causes said container to move upwardly relative to the guard.

### Claim 5 (depends on 1)

The mixer of claim 1 wherein said sensors comprise electrical switches connected in series.

### Claim 6 (depends on 5)

The mixer of claim 5 wherein said support members comprise protuberances and said mounts include mating apertures, engagement of said protuberances within said mating apertures closing said electrical switches.

### Claim 7 (depends on 5)

The mixer of claim 5 wherein said controller includes a relay connected to activate said drive system, said switches being connected in series with said relay.

### Claim 8 (depends on 1)

The mixer of claim 1 wherein said sensors are non-contacting switches.

### Claim 9 (depends on 8)

The mixer of claim 8 wherein said non-contacting switches are magnetic switches.

### Claim 10

A food mixer, comprising:
a housing;
a drive train enclosure mounted to and extending from an upper portion of the housing;
a removable bowl for holding ingredients to be blended;
a bowl support to support the removable bowl below the drive train enclosure;
a motor;
at least two mounts positioned on the housing more than a hand width apart from each other so that said two mounts cannot be contacted simultaneously by the same hand;
a detachable protective guard, positioned between the drive train enclosure and the removable bowl, the guard having a structure for blocking hand access to said container when supported within the bowl support and having at least two support members each arranged to engage an associated one of said mounts such that the guard is cantilevered from said mounts over said bowl, said protective guard being capable of manual detachment from said mounts solely by manipulating the detachable guard itself;
a mixing attachment driven by said motor, said attachment extending downward from the drive train enclosure, through said protective guard, and into the removable bowl to blend the ingredients in the bowl;
independent first and second means for detecting the engagement of said pair of support members and said mounts, respectively;
means for changing the relative spacing between said bowl and said protective guard such that with a first spacing a user is denied hand access to said mixing attachment;
third means independent from said first and second means for detecting that said relative spacing is said first spacing; and
a controller responsive to said first, second and third means to deactivate said motor when either of said support members is disengaged from said mounts or when said relative spacing is not said first spacing.

### Claim 11 (depends on 10)

The mixer of claim 10 wherein said at least two mounts comprise dual drop-in mounts.

### Claim 12 (depends on 10)

The mixer of claim 10 wherein said support members comprise headed pins and said mounts include mating apertures, engagement of said headed pins within said apertures activating said first and second means for detecting the presence of said support members.

### Claim 13 (depends on 10)

The mixer of claim 10 wherein said protective guard is manually detachable to permit replacement of said mixing attachment or to clean said guard.

### Claim 14

A food mixer, comprising:
a housing;
a drive train enclosure mounted to and extending from an upper portion of the housing;
a removable bowl for holding ingredients to be blended;
a bowl support to support the removable bowl below the drive train enclosure;
a motor;
at least two mounts positioned on the housing more than a hand width apart from each other so that said two mounts cannot be contacted simultaneously by the same hand
a detachable protective guard, positioned between the drive train enclosure and the removable bowl, the guard having a structure for blocking hand access to said bowl when supported within the housing, having at least two support members each arranged to engage an associated one of said mounts such that the guard is cantilevered from said mounts over said container, said protective guard being capable of manual detachment from said mounts solely by manipulating the detachable guard itself;
a mixing attachment driven by said motor, said attachment extending downward from the drive train enclosure, through said protective guard, and into the removable bowl to blend the ingredients in the bowl;
a first sensor, associated with a first one of said pair of mounts, to detect the engagement of a first one of said support members and said mount; and
a second sensor, associated with a second one of said pair of mounts, to detect the presence of a second one of said support members in said mount to support said guard on said housing in position over said bowl;
means for changing the relative spacing between said bowl and said protective guard such that with a first spacing a user is denied access to said mixing attachment;
a third sensor to detect that said relative spacing is said first spacing; said first, second and third sensors each being independent of the other two sensors, and
a controller responsive to said first, second and third sensors to deactivate said motor when either of said pair of support members is disengaged from said mounts or when said relative spacing is not said first spacing.