COOLANT CIRCUIT FOR A SELF-PROPELLED WORKING MACHINE COMPRISING MULTIPLE ELECTRIC DRIVE COMPONENTS

Abstract

A coolant circuit for a self-propelled work machine includes multiple electric drive components, including a coolant pump for generating a flow of coolant which circulates in the coolant circuit, a heat exchanger for dissipating thermal energy stored in the coolant, and at least two circuit lines which extend parallel to each other and are embodied to guide the coolant past the drive components respectively assigned to them, in order to absorb thermal energy. A self-propelled work machine, in particular a mobile crane, includes multiple electric drive components and one or more such coolant circuits.

Claims

1-10. (canceled)

11. A coolant circuit for a self-propelled work machine comprising multiple electric drive components, comprising: a coolant pump for generating a flow of coolant which circulates in the coolant circuit; a heat exchanger for dissipating thermal energy stored in the coolant; and at least two circuit lines which extend parallel to each other and are embodied to guide the coolant past the drive components respectively assigned to them, in order to absorb thermal energy.

12. The coolant circuit according to claim 11, wherein the circuit lines cause a substantially equal pressure loss in the coolant flow throughout their extent, wherein at least one of the circuit lines comprises a throttling element, by means of which the pressure loss of the relevant circuit line is adjusted to the pressure loss of the at least one other circuit line.

13. The coolant circuit according to claim 11, wherein the drive components in at least one of the circuit lines are arranged according to a level of their respective operating temperature limit, thermal dissipation and/or relevance to safety, and starting in the flow direction of the coolant with the lowest operating temperature limit, lowest thermal dissipation and/or greatest relevance to safety.

14. The coolant circuit according to claim 11, wherein the circuit lines are arranged between the coolant pump and the heat exchanger in the flow direction of the coolant.

15. The coolant circuit according to claim 11, further comprising at least one connecting line which fluidically connects at least two of the circuit lines and comprises at least one valve for opening and/or closing the connecting line and/or varying the volume flow of the coolant being guided through the connecting line.

16. The coolant circuit according to claim 15, wherein the connecting line connects a first circuit line downstream of at least one drive component in the first circuit line in the flow direction of the coolant to a second circuit line upstream of at least one drive component in the second circuit line in the flow direction of the coolant.

17. The coolant circuit according to claim 16, wherein the at least one valve is configured to be activated, by means of a control device, in order to guide a volume flow of coolant via the connecting line, according to the coolant requirements of a drive component which is supplied with coolant via the connecting line.

18. The coolant circuit according to claim 17, wherein the control device comprises at least one sensor, which detects the temperature of a drive component, and selectively causes the at least one valve to open or close when the drive component drops below or exceeds a temperature threshold which is predefined for the drive component.

19. A self-propelled work machine, comprising multiple electric drive components and a coolant circuit comprising: a coolant pump for generating a flow of coolant which circulates in the coolant circuit; a heat exchanger for dissipating thermal energy stored in the coolant; and at least two circuit lines which extend parallel to each other and are embodied to guide the coolant past the drive components respectively assigned to them, in order to absorb thermal energy.

20. The self-propelled work machine according to claim 19, comprising multiple coolant circuits which are embodied, independently of each other, wherein a first coolant circuit of the multiple coolant circuits is assigned to the undercarriage of the work machine comprising multiple drive components, and a second coolant circuit of the multiple coolant circuits is assigned to the superstructure of the work machine comprising multiple drive components.

Description

[0025] The present invention is explained in more detail below on the basis of preferred embodiments and with reference to the attached figures. The invention can include any of the features described here, individually and in any expedient combination.

[0026] FIG. 1 shows a coolant circuit for a crane undercarriage;

[0027] FIG. 2 shows a coolant circuit for a crane superstructure.

[0028] FIG. 1 shows a coolant circuit 1 for a crane undercarriage which, in addition to a feed flow comprising the coolant pump 2 and a return flow comprising the heat exchanger 3, comprises four circuit lines 4 to 7 which extend parallel to each other between the feed flow and the return flow. The coolant delivered by the pump 2 is fed to all of the circuit lines 4 to 7, in order to cool (in other words, dissipate the waste heat of) the electric drive components 8 to 13 arranged in the respective circuit lines 4 to 7. Via a common return flow, the heated coolant is fed to the heat exchanger 3 in which the stored thermal energy is removed from the coolant again. An expansion tank 25 arranged between the heat exchanger 3 and the pump 2 in the direction of flow of the coolant is used to compensate for thermally induced changes in the volume of the coolant.

[0029] In the example shown in FIG. 1, all of the circuit lines 4 to 7 exhibit an approximately equal pressure loss and/or generate an approximately equal backpressure. This means that the volume flows of coolant being guided through the respective circuit lines 4 to 7 are in a fixed size ratio, without individual circuit lines 4 to 7 being oversupplied or undersupplied. Since the circuit line 7 comprising the inverter 12 for an intermediate circuit of the electrical energy supply and the inverter 13 of the generator 10 exhibits the greatest pressure loss, the other circuit lines 4 to 6 (in which the assigned drive components 8 to 11 cause a smaller pressure loss) are provided with throttling valves 20, such that all of the circuit lines 4 to 7 exhibit an approximately equal pressure loss and/or generate an approximately equal backpressure.

[0030] Within the individual circuit lines 4 to 7, the drive components 8 to 13 are arranged such that the coolant flow first passes the drive components with the lowest operating temperature limit and only then the subsequent drive components with a higher operating temperature limit.

[0031] The coolant circuit 1 shown in FIG. 1 also comprises an electronic control device 23 which is connected for signal transmission to two valves 22 and a temperature sensor 24 and causes the valves 22 to open and/or close according to a temperature value transmitted by the sensor 24. What this specifically means in the example shown is that if the sensor 24 detects a temperature of the accumulator and/or storage battery 9 which is too low, the control device 23 causes the connecting line 21 to open, such that the waste heat discharged to the coolant by the brake chopper 8 is fed to the storage battery 9 via the connecting line 21, in order for it to reach its operating temperature. When the valves 22 are in this state, there is no direct connection between the circuit line 4 and the return flow and no direct connection between the circuit line 5 and the feed flow. All of the coolant guided past the brake chopper 8 is consequently also guided past the storage battery 9.

[0032] The brake chopper 8 converts excess energy, which for example arises from recuperation by braking a drive and cannot be used to charge the storage battery 9 because the storage battery 9 is sufficiently charged, into thermal energy via an electrical resistor, wherein said thermal energy is absorbed by the passing coolant.

[0033] Since it is not to be expected that a high thermal output from both the generator 10 and the inverter of the external power supply 11 will have to be dissipated simultaneously, these components can be arranged in the same line 6.

[0034] FIG. 2 shows a coolant circuit 1 for a crane superstructure, the essential components of which are identical to those of the coolant circuit 1 shown in FIG. 1. The coolant circuit 1 provided for the crane superstructure, however, comprises only two parallel circuit lines 5 and 6 which each supply three drive components 14 to 16 and 17 to 19, respectively, with coolant. In the line 5, these are (in order of increasing permissible operating temperature limit): the electric motor 14 of the lifting mechanism; the inverter 15 of a first air-cooled slewing mechanism motor; and the inverter 16 for the hydraulic pump 17. In the line 6, these are: the water-cooled electric motor for the hydraulic pump, which for example supplies the luffing mechanism and the telescoping mechanism with hydraulic liquid; another inverter 18 for a second air-cooled slewing mechanism motor; and the inverter 19 for the water-cooled lifting mechanism motor 14. Since it may be assumed of the underlying mobile crane that the lifting mechanism will not be permanently operated together with the luffing mechanism or telescoping mechanism (such that their drive components would be simultaneously generating a high level of waste heat), their corresponding drive components 14, 16, 17 and 19 are supplied with coolant via the same circuit lines 5 and 6. In order to avoid local heat spikes, the individual components 14, 16, 17 and 19 of the lifting mechanism and hydraulic pump are distributed crosswise between the circulation lines 5 and 6.