US 4,345,436 A · Control for load sharing pumps

Abstract

Conditional exchanging of working fluid between plural fluid circuits (13A, 13B) having separate supply pumps (18A, 18B) is provided for without continuously bleeding fluid from the pump control pressure lines (21A, 21B). Each circuit (13A, 13B) has a pump control (19A, 19B) responsive to a control pressure, a plurality of fluid motors (14A, 15A, 16A, 14B, 15B, 16B), and a group of resolver valves (38A, 38B) which compare motor pressures and intercommunicate the pump control (19A, 19B) with the most highly pressurized motor (14A, 15A, 16A, 14B, 15B, 16B). At times when fluid from one circuit (13A, 13B) is being delivered to a motor (16A, 16B) of another circuit (13A, 13B), the pressure comparing function of the resolver group (38A, 38B) of the one circuit (13A, 13 B) is extended to include the motor (16A, 16B) of the other circuit (13A, 13B). Among other uses, the system (11) may be used on excavator vehicles having plural fluid motors performing a variety of different functions. Absence of a bleed in the pump control lines (21A, 21B) conserves power and enables precise response of the pumps to demand changes.

Claims12

Dependent claims

In a fluid system (11) having first (14A, 15A, 16A) and second (14B, 15B, 16B) pluralities of fluid operated devices, first (12A) and second (12B) fluid source means for supplying working fluid to said first (14A, 15A, 16A) and second (14B, 15B, 16B) pluralities of fluid operated devices respectively, first (19A) and second (19B) control means for varying the outputs of said first (12A) and second (12B) fluid source means, respectively, in response to control pressures, and crossover means (17) for transmitting fluid from said first source means (12A) to at least one device (16B) of said second plurality of devices (14B, 15B, 16B), the improvement comprising:

first pressure comparing means (38A) for establishing a two way control pressure flow path between said first control means (12A) and the one of a first predetermined group (14A, 15A, 16A, 16B) of said devices that is most highly pressurized at a particular time, said first predetermined group (14A, 15A, 16A, 16B) including said first plurality of devices (14A, 15A, 16A) and at least said one (16B) of said second plurality of devices (14B, 15B, 16B).

A fluid system (11) comprising:

a first pressurized fluid source (12A) having first control means (19A) for varying output pressure in response to variations of a control pressure,
a first plurality of fluid motors (14A, 15A, 16A),
a first plurality of motor control valves (23A, 29A, 34A) each being connected between said first fluid source (12A) and an associated individual one of said first plurality of motors (14A, 15A, 16A),
a second pressurized fluid source (12B) having second control means (19B) for varying output pressure in response to variations of a control pressure,
a second plurality of fluid motors (14B, 15B, 16B),
a second plurality of motor control valves (23B, 29B, 34B) each being connected between said second fluid source (12B) and an associated individual one of said second plurality of motors (23B, 29B, 34B),
crossover means (17) for transmitting fluid supplied by said first source (12A) to at least one of said motor control valves (23B, 29B, 34B) of said second plurality thereof, and
resolver means (38A) for intercommunicating said first control means (19A) with the most highly pressurized one of a group of said motors which includes said motors (14A, 15A, 16A) of said first plurality thereof and which further includes, at least during periods when said crossover means (17) is transmitting fluid, at least one of said motors (14B, 15B, 16B) of said second plurality thereof.

5 more elements

Dependencies are inferred from the claim text.

Control for load sharing pumps

Life of this patent

Control for load sharing pumps

Life of this patent

Abstract

Claims12