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Multiple pump unit and vehicle with multiple pump unit

Multiple pump unit and vehicle with multiple pump unit description/claims

This application claims the benefit of priority from prior Japanese Patent Application No. 2006-348759, filed in Japan on Dec. 26, 2006, the entire contents of which are incorporated herein by reference.

1. Technical Field

The present invention generally relates to a multiple pump unit used for operating a plurality of actuators, and to a vehicle with such a multiple pump unit.

2. Related Art

Hydraulic pumps have been conventionally used for various purposes. For example, work vehicles such as a lawn mower vehicles, tractors, or trucks drive a hydraulic pump with an engine, and the hydraulic pressure produced is used to rotate two wheel-driving hydraulic motors, which are a plurality of actuators, which in turn drive the two front or rear wheels.

Further, a work vehicle such as a lawn mower vehicle or a tractor is sometimes used to drive working machines such as a mower or a cultivator, and to raise and lower the machine. As a result, the concept of creating a dual pump unit by combining two hydraulic pumps and driving the machine via a PTO (power take off) shaft capable of taking out power from the drive source was proposed.

For example, Japanese Patent Laid-Open Publication No. 2003-306052 discloses a pump unit including a PTO shaft and two hydraulic pump bodies. In the disclosed configuration, a first pump shaft and a second pump shaft are operationally connected to an input shaft connected to a drive source, and power transmission between the input shaft and the PTO shaft, and shutoff of the power transmission are made switchable by a hydraulic clutch mechanism provided between the input shaft and the PTO shaft. The first pump shaft drives a first hydraulic pump body, and pressurizes the oil supplied into the first hydraulic pump body from an oil supply port to discharge the oil from a discharge port. The second pump shaft drives a second hydraulic pump body, and pressurizes the oil supplied into the second hydraulic pump body from another oil supply port to discharge the oil from another discharge port.

A first hydraulic motor and a second hydraulic motor are respectively driven by the oil discharged from the first hydraulic pump body and the second hydraulic pump body, and wheels corresponding to them are rotated. Further, the PTO shaft and the working machine are connected by a transmission shaft.

In the case of the pump unit disclosed in Japanese Patent Laid-Open Publication No. 2003-306052, when the drive source is an engine, the engine must be driven whenever the wheels or an attachment are driven. Therefore, it still has room for improvement in the aspect of enhancement of quietness. For example, in the working vehicle including the pump unit disclosed in Japanese Patent Laid-Open Publication No. 2003-306052, when the drive source is an engine, the engine is always driven, and therefore use of the working vehicle in an environment where quietness is desired, such as an area near a residential district, is likely to be difficult due to the noise generated by the engine.

Further, although it has been conventionally conceived of driving one pump with one electric motor, with such a configuration the range of use is small, and usability is low. For example, when two wheels at both left and right sides are driven with one pump, independent control of the wheels is difficult, and it is likely to be difficult to make the turning radius small.

It is an advantage of the present invention to provide a structure usable for many purposes and providing superior quietness, in a multiple pump unit and a vehicle with the multiple pump unit.

A multiple pump unit according to the present invention may be configured as a multiple pump unit used for operating a plurality of actuators, characterized by including a plurality of pump shafts driven by an electric motor, and a plurality of hydraulic pumps driven by the respective plurality of pump shafts, wherein pressurized oil for operating the plurality of actuators is fed out from the plurality of hydraulic pumps.

According to this constitution, a plurality of pump shafts which drive a plurality of hydraulic pumps are driven by the electric motor, and the pressurized oil for operating a plurality of actuators is fed out from the plurality of hydraulic pumps. Therefore, because electric power can be supplied to a secondary battery or the like from a generator or the like driven by an engine, and this electric power can then be supplied to the electric motor from the secondary battery or the like, the engine does not have to be always operated for operating the plurality of actuators. Therefore, the structure capable of providing very quiet operation is obtained. In addition, because the multiple pump unit can be used for a larger number of purposes, usability can be enhanced compared to configurations in which the electric motor drives only one pump shaft constituting a hydraulic pump.

Further, preferably, at least any one of the plurality of hydraulic pumps is a double port pump provided with a plurality of discharge ports in correspondence with one pump shaft, and the pressurized oil for operating the plurality of actuators is fed out from the plurality of discharge ports of the double port pump.

With this constitution, the pressurized oil for operating a larger number of actuators is fed out from the plurality of hydraulic pumps, and a larger number of actuators can be operated. Therefore, usability can be further enhanced.

Further, more preferably, a casing housing the plurality of hydraulic pumps and rotatably supporting a rotary shaft of the electric motor and the plurality of hydraulic pump shafts, and a PTO shaft rotatably supported by the casing are included, the rotary shaft of the electric motor and the plurality of hydraulic pump shafts are operationally connected, and power transmission is made selectively possible between the rotary shaft of the electric motor and the PTO shaft by a clutch mechanism.

According to this constitution, irrespective of the rotation of the electric motor, operation and non-operation of the working machine or the like operationally connected to the PTO shaft can be selected by the clutch mechanism, and usability can be further enhanced.

Further, more preferably, a PTO shaft side pulley fixed to the PTO shaft projecting from the casing is included.

Further, more preferably, a cooling fan is fixed to at least one of a rotary shaft of the electric motor or a hydraulic pump shaft among the plurality of hydraulic pumps

With this constitution, the equipment including the electric motor and the plurality of hydraulic pumps can be easily cooled, making it easier to further enhance performance.

• Provisional Patent
• Utility Patent

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