Method for operating a waste heat utilization device

• US 9,879,569 B2
• Filed: 01/14/2014
• Issued: 01/30/2018
• Est. Priority Date: 01/30/2013
• Status: Active Grant

• Current Assignee: Daimler AG (Mercedes-Benz Group AG)
• Original Assignee: Daimler AG (Mercedes-Benz Group AG)
• Inventors: Franke, Andreas, Gaertner, Jan, Koch, Thomas, Mall, Dominik
• Primary Examiner(s): Matthias, Jonathan
• Application Number:
  US14/764,324
• Publication Number:
  US 20150361832A1
• Time in Patent Office: 1,477 Days
• CPC Class Codes: F01K 23/065 the combustion taking place in an internal combustion piston engine, e.g. a diesel engine
• CPC Class Codes: F01K 23/10 with exhaust fluid of one cycle heating the fluid in another cycle F01K17/025 takes precedence
• CPC Class Codes: F01K 9/003 condenser cooling circuits
• CPC Class Codes: F02G 5/00 Profiting from waste heat of combustion engines, not otherwise provided for
• CPC Class Codes: F02G 5/02 Profiting from waste heat of exhaust gases
• CPC Class Codes: Y02T 10/12 Improving ICE efficiencies

Abstract

A method and a device for operating a waste heat utilization device for an internal combustion engine of a motor vehicle is disclosed. The waste heat utilization device contains a waste heat utilization circuit in which a working medium circulates. A conveyor, an evaporator, an expansion machine, and a condenser are disposed in the waste heat utilization circuit. A basic adjustment of the waste heat utilization circuit is provided, which as a function of a heat input into the working medium adjusts the mass flow rate at the conveyor and/or the ratio between high pressure and low pressure at the expansion machine. In addition, a pilot control is provided which recognizes a change of the operating point of the internal combustion engine and, when the operating point is changed, controls the condensation output of the condenser in accordance with a mass distribution of the working medium in the waste heat utilization circuit optimized to the new operating point.

Claims

1. A method for operating a waste heat utilization device for an internal combustion engine of a motor vehicle, wherein the waste heat utilization device includes:

a waste heat utilization circuit in which a working medium circulates;

a conveyor disposed in the waste heat utilization circuit for conveying the working medium against a high pressure;

an evaporator disposed downstream of the conveyor in the waste heat utilization circuit for vaporizing the working medium;

an expansion machine disposed downstream of the evaporator in the waste heat utilization circuit for producing mechanical energy by expanding the working medium in a gaseous state to a low pressure;

a condenser disposed downstream of the expansion machine in the waste heat utilization circuit for condensing the gaseous working medium; and

a cooling circuit, wherein the cooling circuit cools the condenser,

the method comprising the steps of;

providing the conveyor and/or the expansion machine that are adjustable independently of the cooling circuit;

providing a basic adjustment of the waste heat utilization circuit which, as a function of a heat input into the working medium, adjusts a mass flow rate at the conveyor and/or a ratio between high pressure and low pressure at the expansion machine; and

providing a pilot control which recognizes a change of an operating point of the internal combustion engine, and when the operating point changes, controls a condensation output of the condenser such that a mass distribution of the working medium in the waste heat utilization circuit changes and is adapted to a new operating point.

2. The method according to claim 1, wherein the control of the condensation output of the condenser takes place by a change of a mass flow of a coolant in the condenser.

3. The method according to claim 1, wherein the change in the mass distribution of the working medium is detected by a filling level measuring device disposed in a collector.

4. A waste heat utilization device for an internal combustion engine of a motor vehicle, comprising:

a waste heat utilization circuit in which a working medium circulates;

a conveyor disposed in the waste heat utilization circuit, wherein the working medium is conveyed by the conveyor against a high pressure;

an evaporator disposed downstream of the conveyor in the waste heat utilization circuit, wherein the working medium is vaporized by the evaporator;

an expansion machine disposed downstream of the evaporator in the waste heat utilization circuit, wherein the expansion machine produces mechanical energy by expanding the working medium in a gaseous state to a low pressure;

a condenser disposed downstream of the expansion machine in the waste heat utilization circuit, wherein the condenser condenses the gaseous working medium;

a collector, wherein the collector stores the condensed working medium;

a cooling circuit, wherein the cooling circuit cools the condenser;

wherein the conveyor and/or the expansion machine are adjustable independently of the cooling circuit;

a basic conveyor- or expansion machine-adjusting device which is connected to the conveyor or the expansion machine, respectively, wherein the basic conveyor- or expansion machine-adjusting device controls or adjusts the waste heat utilization device; and

a pilot controller, wherein the pilot controller controls a condensation output of the condenser with a controller which controls a cooling performance adjustment device and, when an operating point of the internal combustion engine changes, controls the condensation output of the condenser such that a mass distribution of the working medium in the waste heat utilization circuit changes and is adapted to a new operating point.

5. The device according to claim 4, wherein a filling level measuring device is disposed in the collector.

6. The device according to claim 4, wherein the cooling performance adjustment device is an adjustable bypass of the condenser cooling circuit.

7. The device according to claim 4, wherein the cooling performance adjustment device is an adjustable cooling circuit pump.

8. The device according to claim 4, further comprising:

a temperature measuring device, wherein the temperature measuring device measures a temperature of a coolant which circulates in the cooling circuit;

wherein the controller is coupled to the temperature measuring device and wherein a cooling performance of the cooling circuit is changeable by the control unit controller.

9. The device according to claim 8, wherein the temperature measuring device has a feed line temperature sensor which detects a temperature of the coolant before the condenser and a return line temperature sensor which detects a temperature of the coolant after the condenser.