Agitating – Mortar mixer type – Movable mixing chamber
Patent
1998-08-13
2000-06-13
Soohoo, Tony G.
Agitating
Mortar mixer type
Movable mixing chamber
60464, B28C 518
Patent
active
060740833
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to a hydrostatic-mechanical drive unit for a mixing drum, especially of a mobile concrete mixer. The drive unit has a hydraulic pump connected to a hydraulic motor via lines. The hydraulic pump is surrounded by a housing. A transmission housing accommodates the hydraulic motor and a planetary transmission. A component of the planetary transmission is in driving connection with an input flange of the mixing drum.
A hydrostatic-mechanical drive unit of the configuration explained above has been disclosed in DE-A 43 13 025. To improve the cooling of the unit, oil is steadily fed from a high-pressure circuit to the drive unit. Also, cooled oil is steadily fed to the interior of the transmission housing in such a manner that cooling of the hydraulic motor also results. The hydraulic motor is preferably a slowly working radial-piston motor. The pistons of the radial-piston motor bear, via rollers, on a cam surface which has a course substantially shaped as a sine wave. Each piston is biased into the cylinder block under the action of a spring component. The spring components can be formed, for example, of compression springs. They produce a constant, positive connection between the rollers of the pistons and the cam surface. It is thus ensured that the piston spaces always remain filled with oil. This arrangement reduces the further oscillation of the concrete mixer drum when an internal combustion engine is shut down.
This invention is based on the problem of further improving the arrangement for preventing further oscillation of the mixing drum without too much extra construction cost.
SUMMARY OF THE INVENTION
This problem is solved with a hydrostatic-mechanical drive unit according to the preamble of the main claim and also the characteristic features.
BRIEF DESCRIPTION OF THE DRAWING(S)
Other features essential to the invention and the advantages resulting therefrom are to be understood from the description that follows of one embodiment of the invention, and the drawings, in which:
FIG. 1 is a hydraulic diagram of a hydrostatic-mechanical mixing drive unit; and
FIG. 2 is a simplified section of a slowly working radial-piston hydromotor having one suction valve.
DESCRIPTION OF THE PREFERRED EMBODIMENT(S)
In FIG. 1 a hydraulic pump 2 is driven by a shaft 1 attached to an internal combustion engine, designated as E. The hydraulic pump 2 is designed as an adjusting unit with reversible directions of rotation. A feed pump 3 is also driven by the shaft 1.
The hydraulic pump is connected with a hydraulic motor 6 by lines 4 and 5. The hydraulic motor 6 drives a concrete mixer drum, designated as D via a downstream planetary transmission 7.
The hydraulic pump 2 is surrounded by a housing 8. A transmission housing 9 surrounds the hydraulic motor 6, the planetary transmission 7, a flush slide 10 and a flush valve 11.
An oil cooler 12 is also located on or in the transmission housing 9.
A line 13 leads to a filter 14 and from there to the feed pump 3. The feed pump 3 sucks oil from the interior of the transmission housing 9, via the line 13 and the filter 14, and conveys it, via a line 15 from which a line 16 branches off, to the respective low-pressure circuit. A pressure-limiting valve 17 is attached to the line 15 or 16.
The oil cooler 12 is loaded with cool air generated by a fan 18.
The pump housing 8 is connected with the oil cooler 12 by a line 19. The section of the line 19 lying after the oil cooler 12, which section is shown in the drawing with dotted lines, discharges in the immediate proximity of the hydraulic motor 6 so that the latter is constantly surrounded with a flow of cooled oil, the accumulating, heated, leakage oil being eliminated by mixing in the interior of the transmission housing.
Lines 20, 21 lead from the lines 4 and 5 to the flush slide 10. Depending on the switching position of the flush slide 10, oil flows steadily from one of the lines 4 or 5 to the line 22 where the flush valve 11 is located, and from there, together with the
REFERENCES:
patent: 4329064 (1982-05-01), Mann et al.
patent: 4542990 (1985-09-01), Fouquet
patent: 5419132 (1995-05-01), Sato et al.
patent: 5746509 (1998-05-01), Gebhard et al.
Japanese Abstract, (Daikin Ind Ltd) vol. 014, No. 536 (M-1052) dated Nov. 27, 1990.
Gebhard Wolfgang
Mann Egon
Soohoo Tony G.
ZF Friedrichshafen AG
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