Self-propelling work machine and method for braking such a work machine

• US 9,744,872 B2
• Filed: 09/09/2014
• Issued: 08/29/2017
• Est. Priority Date: 09/27/2013
• Status: Active Grant

• Current Assignee: Liebherr-Components Biberach Gmbh (Liebherr-International AG)
• Original Assignee: Liebherr-Components Biberach Gmbh (Liebherr-International AG)
• Inventors: Hoffmann, Sebastien Nicolas, Richthammer, Burkhard Emanuel, Sommer, Bernd, Duelli, Stefan, Merkle, Markus, Resch, Juergen
• Primary Examiner(s): SWENSON, BRIAN L
• Application Number:
  US15/025,213
• Publication Number:
  US 20160229295A1
• Time in Patent Office: 1,085 Days
• CPC Class Codes: B60K 25/00 Auxiliary drives B60K16/00 takes precedence; arrangements of tyre-inflating pumps mounted on vehicles B60C23/10; driving tyre-inflating pumps B60C; driving engine auxiliaries F02B
• CPC Class Codes: B60K 6/22 characterised by apparatus, components or means specially adapted for HEVs
• CPC Class Codes: B60K 6/28 characterised by the electric energy storing means, e.g. batteries or capacitors
• CPC Class Codes: B60K 6/46 Series type
• CPC Class Codes: B60L 2200/40 Working vehicles
• CPC Class Codes: B60L 50/10 using propulsion power supplied by engine-driven generators, e.g. generators driven by combustion engines
• CPC Class Codes: B60L 53/00 Methods of charging batteries, specially adapted for electric vehicles; Charging stations or on-board charging equipment therefor; Exchange of energy storage elements in electric vehicles
• CPC Class Codes: B60L 53/50 Charging stations characterised by energy-storage or power-generation means
• CPC Class Codes: B60L 58/10 for monitoring or controlling batteries
• CPC Class Codes: B60L 7/10 Dynamic electric regenerative braking B60L7/22 takes precedence
• CPC Class Codes: B60L 7/18 Controlling the braking effect B60L7/12, B60L7/14, B60L7/16 take precedence
• CPC Class Codes: B60W 10/06 including control of combustion engines
• CPC Class Codes: B60W 10/08 including control of electric propulsion units, e.g. motors or generators
• CPC Class Codes: B60W 10/18 including control of braking systems
• CPC Class Codes: B60W 10/184 with wheel brakes
• CPC Class Codes: B60W 10/196 acting within the driveline, e.g. retarders
• CPC Class Codes: B60W 10/24 including control of energy storage means
• CPC Class Codes: B60W 10/30 including control of auxiliary equipment, e.g. air-conditioning compressors or oil pumps
• CPC Class Codes: B60W 20/00 Control systems specially adapted for hybrid vehicles hybrid vehicle design, B60K6/00; electric vehicles B60L
• CPC Class Codes: B60W 20/14 in conjunction with braking regeneration
• CPC Class Codes: B60W 2300/125 : Heavy duty trucks
• CPC Class Codes: B60W 2300/17 : Construction vehicles, e.g. graders, excavators
• CPC Class Codes: B60W 2710/0627 : Fuel flow rate
• CPC Class Codes: B60W 2710/0644 : Engine speed
• CPC Class Codes: B60W 30/18127 : Regenerative braking
• CPC Class Codes: B60W 30/18136 : Engine braking
• CPC Class Codes: B60Y 2200/411 : Bulldozers, Graders
• CPC Class Codes: B60Y 2200/92 : Hybrid vehicles
• CPC Class Codes: B60Y 2300/18125 : Regenerative braking
• CPC Class Codes: B60Y 2300/43 : Control of engines
• CPC Class Codes: B60Y 2300/60 : Control of electric machines, e.g. problems related to electric motors or generators
• CPC Class Codes: B60Y 2300/91 : Battery charging
• CPC Class Codes: B60Y 2400/604 : AC Machines, e.g. asynchronous motors
• CPC Class Codes: B60Y 2400/61 : Arrangements of controllers for electric machines, e.g. inverters
• CPC Class Codes: B60Y 2400/81 : Braking systems
• CPC Class Codes: B60Y 2400/87 : Auxiliary drives
• CPC Class Codes: E02F 3/7609 : Scraper blade mounted forwardly of the tractor on a pair of pivoting arms which are linked to the sides of the tractor, e.g. bulldozers
• CPC Class Codes: E02F 9/2075 : of the hybrid type for vehicles in general B60W20/00
• CPC Class Codes: E02F 9/2083 : Control of vehicle braking systems
• CPC Class Codes: Y02T 10/62 : Hybrid vehicles
• CPC Class Codes: Y02T 10/70 : Energy storage systems for electromobility, e.g. batteries
• CPC Class Codes: Y02T 10/7072 : Electromobility specific charging systems or methods for batteries, ultracapacitors, supercapacitors or double-layer capacitors
• CPC Class Codes: Y02T 90/12 : Electric charging stations
• CPC Class Codes: Y02T 90/14 : Plug-in electric vehicles
• CPC Class Codes: Y10S 903/93 : Conjoint control of different elements
• CPC Class Codes: Y10S 903/947 : Characterized by control of braking, e.g. blending of regeneration, friction braking

Abstract

The application describes a self-propelling work machine, in the form of a truck, having an electric drive comprising at least one electric motor, a generator drivable by an internal combustion engine for the power supply of the electric drive, and a braking apparatus for braking the work machine, wherein the braking apparatus provides a regenerative braking by the electric drive and a feedback apparatus for feeding back electrical motor braking power of the electric motor to the generator to apply the motor braking power on the internal combustion engine. The application further describes a method for braking the work machine. A braking control apparatus is provided for an automatic connection of a mechanical brake in dependence on the motor braking power fed back to the internal combustion engine and/or in dependence on the operating state of the internal combustion engine acted on by the fed back motor braking power.

Claims

1. A self-propelling work machine having an electric drive comprising at least one electric motor;

the work machine further comprising a generator drivable by an internal combustion engine and for supplying the electric drive with electric current;

the work machine further comprising a braking apparatus for braking the work machine, wherein the braking apparatus provides a regenerative braking by the electric drive and comprises a feedback apparatus for feedback of electrical motor braking power of the electric motor to the generator, wherein a braking control apparatus is provided for automatic connection of at least one mechanical brake in dependence on the electrical motor braking power fed back to the internal combustion engine and/or on an operating state of the internal combustion engine acted on by the fed back motor braking power,

wherein the braking control apparatus comprises a first braking stage in which the braking power takes place only by way of electric motor braking and of applying the electrical motor braking power on the internal combustion engine, wherein, in a first sub-stage, a fuel supply to the internal combustion engine is first reduced with a constant engine speed and, in a second sub-stage with a cut-off fuel supply, a speed increase of the internal combustion engine is permitted for increasing the braking power until a predefined maximum speed is reached.

2. The self-propelling work machine in accordance with claim 1, wherein the braking control apparatus is configured such that first a regenerative braking and second a braking by the mechanical brake takes place when the electrical motor braking power fed back to the internal combustion engine reaches a deceleration capacity of the internal combustion engine and of auxiliary units optionally connected to the internal combustion engine.

3. The self-propelling work machine in accordance with claim 2, wherein the braking control apparatus is configured such that during the regenerative braking a power pick-up of at least one connected auxiliary unit is increased before the mechanical brake is connected.

4. The self-propelling work machine in accordance with claim 2, wherein at least one auxiliary unit connected to the internal combustion engine comprises a cooling apparatus and/or a pump whose power pick-up is controllable.

5. The self-propelling work machine in accordance with claim 1, wherein the feedback apparatus is free of electrical braking resistors.

6. The self-propelling work machine in accordance with claim 1, wherein the electrical motor braking power of the at least one electric motor is completely transferred to the generator connected to the internal combustion engine and mechanical drive power generated by the generator is completely transferred to the internal combustion engine.

7. The self-propelling work machine in accordance with claim 1, wherein the mechanical brake comprises at least one wet brake.

8. The self-propelling work machine in accordance with claim 7, wherein the wet brake comprises a multi-disk-brake with oil cooling.

9. The self-propelling work machine in accordance with claim 1, wherein the braking control apparatus is connectable to a speed detection device for detecting a speed of the internal combustion engine, with the braking control apparatus being configured such that the mechanical brake is connected on an exceeding of a predefined speed of the internal combustion engine and the mechanical brake is released on a falling below of the predefined speed of the internal combustion engine.

10. The self-propelling work machine in accordance with claim 1, wherein the brake control apparatus comprises a braking force regulator for regulating a braking force applied by the mechanical brake, with the braking force regulator configured such that in a braking mode in which the mechanical brake is connected, the braking force applied by the mechanical brake is regulated such that the internal combustion engine is maintained at a maximum permitted speed or at a predefined speed.

11. The self-propelling work machine in accordance with claim 10, wherein the braking force regulator is configured such that an electric motor braking force and/or the mechanical braking force and/or a sum of the electric motor braking force and of the mechanical braking force corresponds to a desired braking force.

12. The self-propelling work machine in accordance with claim 1, wherein the braking control apparatus is connectable to an engine control device for controlling a fuel supply to the internal combustion engine, the engine control device configured such that in braking operation with feedback of electrical motor braking power to the internal combustion engine, the fuel supply is reduced such that the internal combustion engine is maintained at a constant speed.

13. The self-propelling work machine in accordance with claim 1, wherein the feedback apparatus comprises at least one motor inverter associated with the at least one electric motor and at least one generator inverter associated with the generator, the feedback apparatus further comprising at least one intermediate circuit provided between the motor inverter and the generator inverter.

14. The self-propelling work machine in accordance with claim 13, wherein the at least one intermediate circuit is a DC voltage intermediate circuit.

15. The self-propelling work machine in accordance with claim 1, wherein the work machine is a dump truck.

16. A method for braking a work machine, with at least one electric drive comprising at least one electric motor, the work machine further comprising a generator drivable by an internal combustion engine for a power supply of the electric drive, the work machine further comprising a braking apparatus for braking the work machine, wherein the at least one electric motor is operated as a generator and an electrical motor braking power generated is fed back to the generator with a feedback apparatus and a mechanical drive power generated by the generator is applied to the internal combustion engine, wherein a mechanical brake is automatically connected or disconnected by a braking control apparatus in dependence on the electrical motor braking power fed back to the internal combustion engine and/or on an operating state of the internal combustion engine acted on by the fed back electrical motor braking power,

wherein with a small desired braking force in a first braking stage at an unchanging speed of the internal combustion engine, a fuel supply to the internal combustion engine is reduced, with an increased desired braking force in a second braking stage with a cut-off fuel supply, the internal combustion engine is revved up while being acted on by the fed back electrical motor braking power up to a predefined maximum speed, and with a further increased desired braking force the mechanical brake is only connected in a third braking stage when the internal combustion engine has reached the predefined maximum speed, and a maximally achievable braking power of the internal combustion engine and of auxiliary units optionally connected thereto is always still smaller than a desired braking force.

17. The method in accordance with claim 16, wherein in the second braking stage a power pick-up of at least one auxiliary unit connected to the internal combustion engine is increased.

18. The method in accordance with claim 17, wherein the at least one auxiliary unit is a cooling fan or a pump;

and wherein the work machine is a dump truck.