Truck mixer with device to make the drum of the mixer rotate

Abstract

Method to make to rotate a drum of a concrete mixer comprising a vehicle provided 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 method provides to feed an electric motor connected to the drum by means of an electric energy generator unit suitable to selectively feed the electric motor.

Claims

1. Method to make rotate a drum of a truck concrete mixer having a vehicle provided with a first motor which cooperates with a wheeled movement unit, to effect the movement of said vehicle, said method comprising a first step in which a second motor, comprising an electric motor connected to said drum, makes said drum rotate, and a second step in which said electric motor is fed by an electric energy generator unit, wherein said second step provides to: connect said first motor means to an alternator to generate alternate electric energy, convert by means of a first converter the alternate electric energy produced by said alternator into continuous electric energy, accumulate said continuous electric energy in an electric energy accumulator, convert by means of a second converter said continuous electric energy of said accumulator once again into alternate energy, feed said electric motor with the alternate electric energy in order to directly make said drum rotate, connect said accumulator to an external source of electrical energy through a third converter to convert the electric energy supplied by said external source to said accumulator.

2. Method as in claim 1, wherein during said second step said electric energy generator unit transforms at least a part of the mechanical energy produced by said first motor into electric energy.

3. Method as in claim 1, wherein during said second step said at least one accumulator is electrically fed by at least a device to recover kinematic/mechanical energy produced by the brakes of said movement unit.

4. Method as in claim 2, wherein during said second step said at least one accumulator is electrically fed by at least a device to recover kinematic/mechanical energy produced by the brakes of said movement unit.

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: 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; 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 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.

(13) 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.

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

(15) 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.

(16) 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.

(17) 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.

(18) 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.

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

(20) 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.

(21) 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.

(22) 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.

(23) 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.

(24) 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.

(25) 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.