EP0341358A1 — Dual hydraulic hospital bed with emergency bypass…

Claim 1

Independent Claim 233 words

An improved hydraulic system for a hospital bed (10) of the type having a generally rigid platform (32,34,36,50) which has attached to it movable patient supporting surfaces, said movable patient supporting surfaces being movable from a generally horizontal position to an elevated position and including head, thigh and leg portions (52,62,64) characterised in that said improved hydraulic system includes: A. A plurality of hydraulic cylinders (56,66) having extensible and retractable operating rods (58,68) and having said operating rods (58,68) connected to said head, leg and thigh portions (52,62,64), whereby movement of said operating rods (58,68) will move said head, leg and thigh portions (10,62,64); B. A source of hydraulic fluid under pressure connected to said hydraulic cylinders; C. A reservoir (70) for said hydraulic fluid, said reservoir being at substantially atmospheric pressure; D. Control valve means (94,96,118,128), connected in circuit intermediate said source of hydraulic fluid under pressure, said reservoir (70), and said hydraulic cylinders (565,66), selectively operable to direct hydraulic operating fluid to and from selected hydraulic cylinders to extend and retract said operating rods; and E. Emergency bypass hydraulic circuit means (134,136) for draining hydraulic fluid from said cylinders (56,66) to said reservoir without use of said control valve means (94,96) to thereby allow faster retraction of said operating rods (58,68) and consequent faster lowering of said head, thigh and leg portions (52,62,64) than is allowed by said control valve means.

Claim 2

Dependent Claim 233 words

An improved hydraulic system for a hospital bed (10) of the type having a generally rigid platform (32,34,36,50) which has attached to it movable patient supporting surfaces, said movable patient supporting surfaces being movable from a generally horizontal position to an elevated position and including head, thigh and leg portions (52,62,64) characterised in that said improved hydraulic system includes: A. A plurality of hydraulic cylinders (56,66) having extensible and retractable operating rods (58,68) and having said operating rods (58,68) connected to said head, leg and thigh portions (52,62,64), whereby movement of said operating rods (58,68) will move said head, leg and thigh portions (10,62,64); B. A source of hydraulic fluid under pressure connected to said hydraulic cylinders; C. A reservoir (70) for said hydraulic fluid, said reservoir being at substantially atmospheric pressure; D. Control valve means (94,96,118,128), connected in circuit intermediate said source of hydraulic fluid under pressure, said reservoir (70), and said hydraulic cylinders (565,66), selectively operable to direct hydraulic operating fluid to and from selected hydraulic cylinders to extend and retract said operating rods; and E. Emergency bypass hydraulic circuit means (134,136) for draining hydraulic fluid from said cylinders (56,66) to said reservoir without use of said control valve means (94,96) to thereby allow faster retraction of said operating rods (58,68) and consequent faster lowering of said head, thigh and leg portions (52,62,64) than is allowed by said control valve means.

Claim 3

Dependent Claim 23 words

A hydraulic system as claimed in claim 1, characterised in that said source of hydraulic fluid under pressure is an electrically driven pump.

Claim 4

Dependent Claim 24 words

A hydraulic system as claimed in claim 1, characterised in that said source of hydraulic fluid under pressure is a manually operated foot pump.

Claim 5

Dependent Claim 38 words

A hydraulic system as claimed in claim 1, characterised in that said source of hydraulic fluid under pressure is a dual power source which can be an electrically driven pump (72) and a manually operated foot pump (102).

Claim 6

Dependent Claim 139 words

A hydraulic system as claimed in claim 4, characterised in that said control valve means comprises: A. A normally closed, electrically operated extension valve (94,96) connected between each of said hydraulic cylinders and said electric pump (72); B. A normally closed, electrically operated retraction valve (118,128) connected between each of said hydraulic cylinders (56,66) and said reservoir; C. A manual selector valve (76), connected between said cylinders and said manually operated pump (102), being operable to direct hydraulic fluid from said manually operated pump (102) to any one of said hydraulic cylinders (56,66); and D. a normally closed, manually operated dump valve, connected to said manual selector valve and said reservoir, whereby opening of said dump valve will cause said cylinder that is connected to said manual selector valve to return the hydraulic fluid in it to said reservoir.

Claim 7

Dependent Claim 39 words

A hydraulic system as claimed in claim 5, characterised in that said head portion (52) is operated by two hydraulic cylinders which operate as a unit and are controlled by a single extension valve and a single retraction valve.

Claim 8

Dependent Claim 141 words

A hydraulic system as claimed in any one of the preceding claims, further characterised in that it includes: A. A hydraulic elevation cylinder (42) having an extensible and retractable operating rod (44) connected to said rigid platform (32); B. A base frame to which said hydraulic elevation cylinder is attached; and C. Second control valve means (92,110), connected in circuit intermediate said source of hydraulic fluid under pressure, said reservoir and said hydraulic elevation cylinder (42), selectively operable to direct hydraulic fluid to and from said hydraulic elevation cylinder (42) to thereby raise and lower said rigid platform (32) said second control valve means (92,110) being connected such that it will not allow hydraulic fluid to flow through said emergency bypass hydraulic circuit means, thereby maintaining said rigid platform at its chosen elevation when said emergency hydraulic circuit means is activated.

Claim 9

Dependent Claim 80 words

A hydraulic system as claimed in any one of the preceding claims, characterised in that said emergency bypass hydraulic circuit includes: A. A normally closed, manually operated emergency valve, connected in circuit to all of said hydraulic cylinders and to said reservoir and bypassing said control valve means; and B. A one-way check valve, connected in circuit intermediate each of said hydraulic cylinders and said emergency valve and positioned to allow hydraulic fluid flow only away from said hydraulic cylinders.

Dual hydraulic hospital bed with emergency bypass circuit

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