US 5,633,452 AGranted

Low pressure warning for hydraulic system of platform float suspension

AssigneeDeere & Company

InventorThomas D. Bebernes

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Abstract

An agricultural implement includes a header or platform suspended from a main frame by a suspension permitting movement of the header between a lowered working position and a raised transport position. The suspension includes single-acting float cylinders and a single-acting lift cylinder controlled by an electrohydraulic control system including a programmable microprocessor in which a signal representative of a minimum acceptable float pressure may be set. The microprocessor contains an electronic switch that couples a warning device lead to ground to effect energization of the warning device in response to the microprocessor receiving an electronic signal representative of a float circuit pressure below the minimum acceptable float pressure. In one embodiment, the microprocessor contains a timing device which is triggered whenever a control switch is connected to energize a "lower" signal lead the timing device being set to time out when sufficient time has elapsed to ensure that the header has reached its working position. The timing device works to suppress the signal representative of the float circuit pressure so that a premature energization of the warning device does not occur when a low float pressure is due to the header being elevated from the ground. In another embodiment, a normally open mechanical switch is connected in series with the electronic switch and is closed only when the header reaches its working position. Replenishing of float pressure to a desirable level may be done either manually or automatically once the low pressure warning device has been energized.

Claims7

Dependent claims

In combination with an agricultural implement including a crop processing header suspended from a main frame of the implement for movement between a raised transport position and a lowered working condition by a float suspension including at least one single-acting float cylinder coupled to a accumulator in a closed hydraulic float pressure circuit, an electrohydraulic float pressure control valve means coupled to a source of fluid pressure and a sump and to said float pressure circuit and being responsive to electrical "increase" and "decrease" signals for respectively coupling the pump to the float pressure circuit for increasing the fluid pressure therein, and for coupling the sump to the float pressure circuit for decreasing the fluid pressure therein, an electrohydraulic control system for apprising an operator of the fact that float pressure in said float pressure circuit is below a minimum acceptable operating pressure, comprising:

a programmable microprocessor including signal storing means for storing a preset electrical signal representative of a minimum acceptable float pressure and including a normally open electronic switch coupled to a grounded output;
a warning signal control lead containing at least one warning device and being coupled between a source of electrical power and a first microprocessor input port connected to said electronic switch, with said warning device being energized only when said electronic switch is closed;
a float pressure transducer means coupled between said float circuit and a second input port of said microprocessor and being operative for producing, and conveying to said microprocessor, an electrical signal representative of said float circuit pressure;
a header position monitoring means coupled to said electronic switch;
and said microprocessor including signal processing means coupled for effecting closure of said electronic switch only when said float pressure transducer produces an electrical signal representative of a pressure below said preset minimum acceptable pressure, and when said header position signal means produces an electrical header position signal indicating said header is in its working condition.

2 more elements

In a combination with an agricultural implement having a main frame, a header, a suspension coupling said header to said main frame for movement between transport and working positions and including at least one single-acting float cylinder coupled in a float pressure circuit including an accumulator, an electrohydraulic float pressure control valve means connected between said float pressure circuit and a sump and pump and being responsive to an electrical "increase" signal for connecting said pump to said float pressure circuit for increasing float pressure in said circuit and being responsive to an electrical "decrease" signal for connecting said sump to said float pressure circuit for decreasing float pressure in said circuit, said suspension including at least one hydraulic lift cylinder for effecting movement of said header between said transport and working positions, and an electrohydraulic lift cylinder control valve means connected between said lift cylinder and said sump and pump and being responsive to an electrical "raise" signal for moving said header to said transport position, and being responsive to an electrical "lower" signal for moving said header to said working position, a low pressure warning system for apprising an operator of the existence of an unacceptably low working pressure in said float pressure circuit, comprising:

a source of electrical power;
a warning device connected in a warning device lead coupled to said source of electrical power;
a normally open electronically controlled grounding switch means connected in said warning device lead between said warning device and a ground connection;
said grounding switch being responsive for coupling said warning device lead to ground only when receiving an electrical float pressure signal representative of an unacceptable low float pressure for adequately supporting the header in its working position together with an electrical header position signal representative of said header being in its working position;
and electrical control means for said electronic switch including a float pressure sensing means for providing said electrical float pressure signal and including a header position indicating means for providing said electrical header position signal, whereby the existence of an unacceptable float pressure while the header is in its working position will result in the energization of said warning device.

2 more elements

Dependencies are inferred from the claim text.