Truck mixer with a device to make the drum of the concrete mixer rotate and corresponding method

Abstract

Truck mixer comprising a vehicle provided with a heat engine which cooperates with a movement unit having wheels, to effect the movement of the vehicle, a concrete mixer mounted on the vehicle and comprising a drum, and a device to selectively make the drum rotate. The device comprises an electric motor connected to the drum, and an electric energy generator unit suitable to selectively feed the electric motor.

Claims

1. Truck mixer comprising a vehicle provided with a first motor, connected by a drive shaft to a movement unit having wheels to effect the movement of said vehicle, a concrete mixer mounted on said vehicle and comprising a drum, and a second motor to selectively make said drum rotate, said second motor comprising an electric motor connected mechanically to said drum, and an electric energy generator unit suitable to selectively feed said electric motor, wherein said electric energy generator unit comprises: an alternator connected to said drive shaft of the first motor by a driven shaft through the interposition of a speed reducer to transform the mechanical energy of the drive shaft into electric energy; a first tension converter that transforms from alternate tension to a continuous tension connected to said alternator in order to convert the electric energy produced by said alternator; at least a continuous electric energy accumulator connected to said first converter; a second tension converter that transforms from continuous tension to alternate tension connected to said accumulator in order to supply alternate electric energy to said electric motor; a third tension converter that transforms from alternate tension to continuous tension connected to said accumulator to convert the electric energy supplied by an external source of electric energy to said accumulator.

2. Truck mixer as in claim 1, wherein it also comprises at least a device to recover kinetic/mechanical energy, produced by the brakes of said movement unit, and is suitable to be associated to said electric motor.

3. Truck mixer as in claim 2, wherein said device to recover kinetic/mechanical energy is connected to said accumulator.

4. Truck mixer as in claim 1, wherein said first motor comprises a heat engine and said alternator is selectively connected to the drive shaft of said heat engine.

5. Truck mixer as in claim 1, wherein said electric motor is connected to said drum by reduction members.

6. Truck mixer as in claim 1 wherein said second motor is arranged only to selectively rotate said drum and does not provide motive power to said drive shaft or to said wheels.

7. Truck mixer as in claim 1 wherein the accumulator is interposed between the alternator and the electric motor.

8. Truck mixer as in claim 7 wherein the first converter is interposed between said alternator and said accumulator, the second converter is interposed between said electric motor and said accumulator and the third converter is interposed between the external source and said accumulator.

9. Truck mixer comprising a vehicle provided with a heat engine operatively connected by a drive shaft to a movement unit having wheels to effect movement of the vehicle, a concrete mixer having a drum is mounted on said vehicle, a drum rotating device that selectively rotates the drum via an electric motor that is mechanically connected to said drum, and an electric energy generator unit that selectively feeds the electric motor, the electric generator unit including: an alternator connected to said drive shaft via a driven shaft to transform the mechanical energy of said drive shaft into electric energy, a first converter that transforms an alternate tension to a continuous tension is connected to said alternator for converting electric energy produced by said alternator, a continuous electric energy accumulator connected to said first converter, a second converter that transforms from continuous tension to alternate tension is connected to said accumulator for supplying alternate electric energy to said electric motor, and a third converter that transforms from alternate tension to continuous tension is connected to said accumulator for converting the electric energy supplied by an external source of electric energy to said accumulator.

10. Truck mixer as in claim 9, wherein it also comprises at least a device to recover kinetic/mechanical energy, produced by brakes of said movement unit, and is suitable to be associated to said electric motor.

11. Truck mixer as in claim 10, wherein said device to recover kinetic/mechanical energy is connected to said accumulator.

12. Truck mixer as in claim 9, wherein said alternator is selectively connected to the drive shaft of said heat engine.

13. Truck mixer as in claim 9, wherein said electric motor is connected to said drum via reduction members.

14. Truck mixer as in claim 9, wherein said first converter is interposed between said alternator and said accumulator, said second converter is interposed between said accumulator and said electric motor, and said third converter is interposed between said accumulator and said external source of electric energy.

Description

DESCRIPTION OF THE DRAWINGS

(1) These and other characteristics of the present invention will become apparent from the following description of a preferential form of embodiment, with reference to the attached drawings wherein:

(2) FIG. 1 is a lateral and schematic view of a truck mixer according to the present invention;

(3) FIG. 2 is a schematized view of the truck mixer in FIG. 1.

DESCRIPTION OF ONE FORM OF EMBODIMENT

(4) With reference to FIG. 1, a truck mixer 10 according to the present invention comprises a vehicle 11, for example a truck, of any known type, provided with a frame 12 on which a rotating drum 16 of a concrete mixer 15 is mounted. The capacity of the drum 16 is comprised, for example, between 4 cubic meters and 12 cubic meters.

(5) The vehicle 11 is provided with a main motor unit 13 which comprises a heat engine 20 (FIG. 2), for example the diesel type, fed by fuel contained in a tank 19. The heat engine 20 is provided with a drive shaft 21 provided to make a transmission shaft 22 of a movement unit 14, provided with drive wheels 27, rotate by means of a clutch 23 and a gearbox 24, of any known type.

(6) The heat engine 20, which is for example able to supply power comprised between 250 kW and 350 kW, by means of the movement unit 14, allows the vehicle 11 to move along the road, for example from the concrete production plant to a building site or vice versa.

(7) One or more electronic devices to recover kinetic/mechanical energy 28, also known as KERS (Kinetic Energy Recovery System) are associated with the drive wheels 27, and allow to recover part of the kinetic/mechanical energy of the movement unit 14, which would otherwise be dispersed by the brakes in the form of heat, during the deceleration and braking of the truck mixer 10.

(8) A device 29 suitable to make the drum 16 selectively rotate is mounted on the vehicle 11.

(9) In this case the device 29 comprises an electric energy generator unit 30, suitable to feed an electric motor 31, for example of the three-phase type, which is connected mechanically, for example by means of reduction members such as a speed reducer 32, to the drum 16.

(10) The electric energy generator unit 30 comprises an alternator 35, which is connected to the drive shaft 21, by means of a driven shaft 36 with the possible interposition of a speed reducer 37.

(11) The alternator 35 is suitable to transform the mechanical energy of the drive shaft 21 into electric energy, in the form of alternate current, which is subsequently transformed into a continuous current needed to load one or more electric energy accumulators 40, which are rechargeable, of the lithium type for example.

(12) The electric energy generator unit 30 also comprises the following three conversion means of electric energy, in this case three current converters:

(13) a first converter 41, to transform the alternate tension produced by the alternator 35 into continuous tension to feed the at least one accumulator 40;

(14) a second converter 43, in this case a current inverter, to transform the continuous tension available from the accumulators 40 into an alternate tension, needed to feed the electric motor 31, and

(15) another and possible third converter 42, to transform the alternate tension, coming from an external electric network 45, into a continuous tension, needed to feed the accumulators 40. The first converter 41 and the third converter 42 can each comprise one or more current rectifiers to allow the adequate feed of the accumulators 40.

(16) The electric motor 41, fed by the electric energy generator unit 30, is able to supply the power needed, for example comprised between 50 kW and 80 kW, for the rotation of the drum 16.

(17) The accumulators 40 can be recharged in one of the three following modalities.

(18) A first recharging modality provides to connect the electric energy generator unit 30 to an external electric network 45. In this case the alternate current supplied by the external electric network 45 is converted, through the third converter 42, into a continuous current to charge the accumulators 40. Recharging the accumulators 40 by a connection to the electric network 45 can be quick if an industrial network is used or slower if a domestic-type network is used. To this purpose, the electric energy generator unit 30 can be provided with suitable electric components to allow connection either to a domestic network or to an industrial network.

(19) A second recharging modality provides to use the mechanical energy derivable from the drive shaft 21. Indeed, by means of the driven shaft 36, this energy is able to make the alternator 35 active, which by means of the first converter 41 is able to supply the accumulators 40 with the energy needed to recharge them.

(20) A third recharging modality provides that the accumulators 40 are recharged using part of the kinetic/mechanical energy of the movement unit 14, by means of electronic devices to recover kinetic/mechanical energy 28.

(21) The electric motor 31 is fed directly by the accumulators 40 which, depending on the functioning conditions, are recharged directly either by the alternator 35, or by the electric network 45 or by the electronic devices to recover kinetic/mechanical energy 28 or alternatively by a combination of these three. This solution allows to optimize the charging of the accumulators 40 independently of the specific functioning needs required instantaneously by the electric motor 31. This allows to obtain an extremely versatile electric energy generator unit 30, with high functioning yields, and having a high functioning autonomy.

(22) The truck mixer 10 as described heretofore functions as follows.

(23) When the truck mixer 10 is stopped for a relatively long period, longer than an hour for example, such as when it is in a concrete production plant to be filled with concrete, the aforementioned first modality is used to charge the electric energy accumulators 40.

(24) When the truck mixer 10 is moving, and the drum 16 is made to rotate slowly by the electric motor 31, then there is also the simultaneous recharging of the accumulators 40, using part of the mechanical energy of the drive shaft 21, that is, by means of the second recharging modality, and possibly part of the electric energy produced by the electronic devices 28, using the third recharging modality.

(25) On the other hand, when the truck mixer 10 is stopped in the building site or nearby, and the drum 16 must continue to rotate, the electric motor 31 is fed exclusively using the electric energy of the accumulators 40. This step is characteristic of the functioning of the truck mixer 10 during the concrete-unloading step, as the accumulators 40 are completely charged.

(26) In the case where the accumulators 40 are completely discharged, it is always possible to take power from the heat engine 20 to be converted into electric energy using the alternator 35.

(27) It is clear that modifications and/or additions of parts may be made to the truck mixer 10 as described heretofore, without departing from the field and scope of the present invention.

(28) It is also clear that, although the present invention has been described with reference to a specific example, a person of skill in the art shall certainly be able to achieve many other equivalent forms of truck mixer, having the characteristics as set forth in the claims and hence all coming within the field of protection defined thereby.