Pumps – Condition responsive control of drive transmission or pump... – Adjustable cam or linkage
Patent
1998-04-13
2000-04-11
Moulis, Thomas N.
Pumps
Condition responsive control of drive transmission or pump...
Adjustable cam or linkage
417216, F04B 126, F04B 4900
Patent
active
060481773
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a device for the output regulation of at least one variable displacement pump driven by a motor, delivering into a working line, and to a method of regulating the output of a variable displacement pump, driven by a motor, delivering into a working line.
2. Discussion of the Prior Art
There is shown in FIG. 2 a device for output regulation, such as is known from German patent 44 05 234, upon which the claim preamble is based. The hydrostatic variable displacement pumps 1 and 2 illustrated in FIG. 2, such as for example axial piston pumps of swash plate construction, are connected via respective working lines 3 to respective not-illustrated consuming devices such as for example the travel drive and the excavator drive motor of an excavator, and are connected via respective suction lines 4 to a tank 5. The two variable displacement pumps 1, 2 are driven by means of a common drive motor 6, such as for example an internal combustion engine, and rotate with the same speed of rotation. For varying their displacements there are provided respective setting devices, each comprising two single acting hydraulic setting cylinders 7, 8.
A setting piston 9 is displaceably arranged in each setting cylinder 7, 8 and is coupled via a piston rod 10 with a setting member 11, 12 of the respective variable displacement pump 1 or 2. Each setting piston 9 bounds with its larger piston surface, away from the piston rod 10, a pressure chamber 13 in the respective setting cylinder 7 or 8. The pressure chambers 13 of the setting cylinders 7 are connected via respective setting pressure lines 14 to the working line 3 associated with the respective variable displacement pump 1 or 2. From these working lines 3 there lead respective pressure lines 15 to the pressure chambers 13 of the setting cylinders 8, in which pressure chambers there are arranged respective compression springs 16 which act upon the swash plate of the variable displacement pump 1 or 2 in the direction of maximum displacement, if appropriate aided by the working pressure taken off from the respective working line 3 via the respective pressure line 15, by way of the piston 9, the piston rod 10 and the setting member 12. The piston surfaces of the setting pistons 9 away from the piston rod 10 in the setting cylinders 7 are greater than those of the setting pistons 9 arranged in the setting cylinders 8, so that working pressure which builds up as a setting pressure during the operation of the variable displacement pumps 1, 2 in the pressure chambers 13 of the setting cylinders 7, via the setting pressure lines 14, adjusts the swash plates of the respective variable displacement pumps 1, 2 in the direction of minimum displacement, by way of the piston 9 and the piston rod 10. Respective adjustable stops 17 in the pressure chambers 13 of the setting cylinders 7 serve to limit the maximum displacements of the variable displacement pumps 1, 2 to different values.
Respective regulation valves 18 are arranged in the setting pressure lines 14 and divide these lines into respective setting pressure line sections 19, 20 which lead to the respective working line 3 and to the respective setting cylinder 7. Each regulation valve 18 is constituted as a continuously adjustable 3/2-port directional control valve and has two working connections to the setting pressure line sections 19 and 20 and a working connection to a relief line 21 leading to the tank 5, into which there opens a leakage oil line 22 of the respective variable displacement pump 1 or 2. In the initial disposition shown in FIG. 1, the working connection to the setting pressure line section 19 is blocked, whilst the other working connections are open. From each setting pressure line section 19, a control pressure line 23 leads to a control connection of the associated regulation valve 18 and makes possible its adjustment in the direction of an end position in which the working connections to the setting pressure line section 20 and the
REFERENCES:
patent: 5176504 (1993-01-01), Moriya et al.
patent: 5182908 (1993-02-01), Devier et al.
Erkkilae Mikko
Obertrifter Bernd
Vogl Karl-Heinz
zu Hohenlohe Felix
Brueninghaus Hydromatik GmbH
Gimie Mahmoud M.
Moulis Thomas N.
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