US20100132380A1

US20100132380A1 - Thermoelectric heat transferring unit

Info

Publication number: US20100132380A1
Application number: US12/292,992
Authority: US
Inventors: II Bruce F. Robinson
Original assignee: Direct Equipment Solutions GP LLC
Current assignee: Direct Equipment Solutions GP LLC
Priority date: 2008-12-02
Filing date: 2008-12-02
Publication date: 2010-06-03

Abstract

A thermoelectric heat transferring unit for transferring heat between an enclosed space and outside of the enclosed space includes a thermoelectric module, a control module, an air intake duct, and an air return duct. The thermoelectric module includes an upper air flow chamber arranged on the enclosed-space side, a lower air flow chamber arranged on the external side, and at least one array of thermoelectric chips sandwiched directly between the upper chamber and the lower chamber. Each of the chambers has a heat sink with heat sink fins and is connected to the thermoelectric chips. The control module controls the heat to be transferred from the upper chamber via the thermoelectric chips to the lower chamber in a cooling mode, and controls the heat to be transferred from the lower chamber via the thermoelectric chips to the upper chamber in a heating mode.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention
The invention generally relates to a thermoelectric heat transferring unit configured to cool or heat an enclosed space without using liquid as medium or compressor. In particular, the unit uses peltier chips for air to air cooling for a tractor or the like to cool a sleeping space therein when the tractor engine is idle/off.
2. Description of the Related Art
A tractor is a truck portion of a semi-tractor-trailer unit or train which is designed to pull a semitrailer by means of a fifth wheel mounted over the rear axle(s). A tractor is also called a truck tractor, highway tractor, semi, semi-tractor, or tractor-trailer. There are various designs of such a sleeping space, including a living quarter in an over-the-road truck, etc. As more and more states passed laws imposing fines for leaving a tractor in idle while the driver is sleeping or waiting for a pickup, there is a demand for improved cooling unit for the sleeping pace inside a tractor which can operate without turning on the tractor engine.
A thermoelectric effect directly converts temperature differences to electric voltage and vice versa. A thermoelectric device creates a voltage when there is a different temperature between both sides. Conversely, when a voltage is applied to the device, it creates a temperature difference. This effect can be used to generate electricity, to measure temperature, to cool or heat objects, etc. A Peltier-effect cooler/heater or thermoelectric heat pump is a solid-state active heat pump which transfers heat from one side of the device to the other. Peltier cooling is one form of thermoelectric cooling (TEC).
U.S. Pat. No. 6,705,089 provides a two-stage cooling system employing thermoelectric modules. The two-stage system only cools but does not heat a target component 50 (such as an integrated circuit chip). In addition, the system requires two cooling stages, one of which requires a liquid reservoir. A second stage cooling apparatus 400 has two arrays of thermoelectric modules 422 sandwiching a liquid-cooled plate 424, and two sets of air-cooled heat sinks 426, 428 respectively connected to one of the modules 422. The first stage cooling apparatus 410 is aligned with the same axis as second stage cooling apparatus 420 so that air generated by fan 412 passes through both first stage cooling apparatus 410 and second stage cooling apparatus 420, especially across heat sinks 426, 428. In particular, the heat is transferred from the target component 50 to the cooling liquid, then the liquid-cooled plate 424, the thermoelectric modules 422 and finally the heat sinks 426, 428.
The present invention applies peltier chips to solve the above-mentioned problem without using liquid as medium or any compressor.

SUMMARY OF THE INVENTION

It is a purpose of this invention to provide a thermoelectric heat transferring unit without using liquid or hazardous medium like Freon, i.e., a suffocation hazard, that can leak in a confined space.
It is another purpose of this invention to provide a thermoelectric heat transferring unit with minimum moving parts for easy operation and maintenance.
It is another purpose of this invention to provide a thermoelectric heat transferring unit that is self contained and easily installed in a sleeper cab of a tractor.
It is another purpose of this invention to provide a thermoelectric heat transferring unit performing both cooling and heating without using additional connections or fuel sources.
It is still another purpose of this invention to answer persistent requests for a thermoelectric heat transferring unit to cool and heat the sleeping space in a tractor.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and additional features and characteristics of the present invention will become more apparent from the following detailed description considered with reference to the accompanying drawings in which like reference numerals designate like elements and wherein:

FIG. 1 shows a thermoelectric heat transferring unit of the invention in a tractor;

FIG. 2 is a top exploratory view of the thermoelectric heat transferring unit shown in FIG. 1;

FIG. 3 is a perspective view of the thermoelectric heat transferring unit shown in FIG. 1 in conjunction with batteries and an alternator;

FIG. 4 is a side view of the thermoelectric cooling and heating module 100 of the thermoelectric heat transferring unit shown in FIG. 2;

FIGS. 5A-B show the air flows inside the thermoelectric cooling and heating module 100 of the thermoelectric heat transferring unit shown in FIG. 2, FIGS. 5C-D show the air flows inside another embodiment of the thermoelectric cooling and heating module 100 of the thermoelectric heat transferring unit;

FIGS. 6A-B are perspective views of the thermoelectric heat transferring unit shown in FIG. 1;

FIG. 7 is an operation flow chart of the thermoelectric heat transferring unit shown in FIG. 1;

FIG. 8 is a simplified diagram of the thermoelectric cooling and heating module and an electronic control and power module of the thermoelectric heat transferring unit; and

FIGS. 9A-B are voltage supply diagrams of from the electronic control and power module to the thermoelectric cooling and heating module.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

With reference to the figures, like reference characters will be used to indicate like elements throughout the embodiments and views thereof. The thermoelectric heat transferring unit 1000 (interchangeably, a Thermoelectric Cabin™ (TEC) unit) as shown in FIG. 1 is installed in a bunk storage space 40 in a sleeping and living space 30 (an area to be cooled or heated by the TEC unit) of the tractor 10. The space 30 is usually separated from the seating area of the tractor 10 by a curtain 20 or the like. For example, to cool the space 30 in a sleeper cab for the person 5 sleeping therein, the TEC unit 1000 intakes external air flow 36 thereinto, processes the airflow 36 and then sends the cooled air flow 34 into the space 30. Concurrently, the TEC unit 1000 intakes warm air flow 32 from the space 30 thereinto, processes the warm airflow 32 and then exhausts the warm air flow 38 outside the tractor 10.
FIG. 2 is a top exploratory view of the TEC unit 1000 shown in FIG. 1. The TEC unit 1000 includes: (A) a thermoelectric cooling and heating module 100 (interchangeably, a TEC module) enclosed in an insulated ducting area, (B) an electronic control and power module 200 housed in protective area with ventilation slots, (C) power cables 300 to the TEC module 100 and fans, (D) a cabin side intake duct and fan assembly 400, (E) a cabin side return duct and fan assembly 450, (F) a wire 600 to a hand held controller 950, (G) a power plug 700 for 12 v input power from batteries 2000, and (H) a main power circuit breaker 750. The TEC unit 1000 provides 120 CFM (cubic feet per minute) air to the sleeper cab of a size about 440 cubit foot.
FIG. 3 is a perspective view of the thermoelectric heat transferring unit shown in FIG. 1 in conjunction with batteries and an alternator. The TEC unit (the central processing unit of the system) is connected via two cables to, for example, eight 100 amp/hour batteries 2000. The batteries 2000 are connected via another two cables to a 270 amp alternator 3000 that recharges the batteries. An external fan 4000 is added to the TEC unit to balance the air flow and improve efficiency. The model and the total number of the batteries 2000 as well as the model of the alternator 3000 can be varied based upon the required cooling capability. The hand controller 950 may be a custom-made or commercially available unit that allows the user to control heating and cooling by selecting at least operation Mode, Intensity, and Fan Speed as discussed below.
FIG. 4 is a side view of the thermoelectric cooling and heating module 100 of the thermoelectric heat transferring unit shown in FIG. 2. The TEC module 100 includes at least one array of thermoelectric chips 110 sandwiched between an upper (cabin side) air flow chamber 140 and a lower (external side) air flow chamber 130. Each of the chambers 130, 140 has a heat sink 150/120 (with heat sink fins 160) connected to the array of thermoelectric chips 110. The chambers 130, 140 are sealed and insulated while physically connected via the array of thermoelectric chips 110 that transfer heat from one side to the other. The air flows in the two chambers do not mix. A thermal insulation material 170 is filled in the void spaces around the TEC module 100 to prevent thermal backflows from one heat sink to the other, as well as to absorb noise. The thermal insulation material 170 may be any commercially available material, such as cellulose, fiberglass, rock wool, polystyrene, urethane foam, vermiculite, etc. The thermoelectric chips 110 transfer heat from one side to the other, depending on the modes of operation to be explained later.
FIGS. 5A-B show the air flows inside the TEC module 100 of the thermoelectric heat transferring unit shown in FIG. 3. FIG. 5A is a top exploratory view of the TEC module 100 showing the upper chamber 140 divided into right and left sides by a divider 145. the divider 145 is a center ridge ¾ the size of the module 100 to separate the air flow. The intake air is blown across cool side heat sinks at 200 CFM on one-half of the upper chamber (left side) by an intake fan, and exhausted out by an exhaust fan on the other half of the upper chamber (right side). This divider 145 allowed the module 100 to keep the cool air in the chamber longer.
The air flow in the upper chamber 140 is channeled so that it flows over the heat sink fins in line with the fins 160, and the air is not allowed to flow above or around the heat sink fins. As such, the air in the upper chamber 140 is drawn from the cabin space 30 and returned back into the conditioned space 30. Using the same example depicted in FIG. 1, to cool the space 30, the TEC module 100 intakes the warm air flow 32 from the cabin space 30 via the intake duct/fan assembly 400 into the upper chamber 140 to pass the back of the upper chamber 140 and then exhaust out of the upper chamber 140 back to the space 30 via the return duct/fan assembly 450 as the cooled air flow 34. For example, the duct has a diameter of four inches, and the fans have a diameter of 120 mm and produce 175 CFM air.
FIG. 5B is a side view of the TEC module 100 showing only the right side of the upper chamber 140 in conjunction with the lower chamber 150. The air flow in the lower chamber 150 is similarly channeled across the heat sink fins from the external environment. For example, the TEC module 100 intakes the external air flow 36 via an external side intake duct/fan assembly 500 (FIG. 6B) into the lower chamber 150 and then exhausts the warm air flow 38 via an external side exhaust duct/fan assembly 550 outside the tractor 10.
FIGS. 5C-D show the air flows inside another embodiment of the thermoelectric cooling and heating module 100 of the thermoelectric heat transferring unit. In this embodiment, there is still a divider 145, but the air flows in and out via two opposite sides of the upper chamber 140, rather the same side as the embodiment depicted in FIG. 5A. The TEC module 100 intakes the warm air flow 32 from the cabin space 30 from one side of the upper chamber 140 and then exhaust out of the upper chamber 140 back to the space 30 via the return duct/fan assembly 450 at the other side of the chamber 140 as the cooled air flow 34.
FIGS. 6A-B are perspective views of the thermoelectric heat transferring unit shown in FIG. 1. FIG. 6A shows the intake duct/fan assembly 400, the return duct/fan assembly 450, the power plug 700, the main power circuit breaker 750, an outer casting 900, and the hand held controller 950. The outer casting 900 may be made of aluminum or steel with dimensions approximately 36 inches long by 36 inches wide and 10 inches deep, for example. The TEC module 100 has dimensions of 18.25 inches long by 6.0 inches wide and 5 inches deep. FIG. 6B shows the bottom of the outer casting 900 with a pair of the external side intake duct/fan assemblies 500 and a pair of the external side exhaust duct/fan assemblies 550.
FIG. 7 is an operation flow chart of the thermoelectric heat transferring unit shown in FIG. 1. The user turns on the TEC Unit 1000 (Step 701), so the unit 1000 can start in the same mode/setting as at shutdown last time: cooling/heating intensity (intense-mild) and fan (hi or low) (Step 702). Thereafter or alternatively, the user is invited to change settings using the hand held control 950 (Step 703). Once the unit is switched on, the user can set operation Mode, Intensity, and Fan Speed.
For example, the operation Mode can be Cooling or Heating. A control switch on the hand held controller 950 determines which direction the unit is transferring heat. In the Cooling Mode, the chips 110 transfer heat from the top heat sink 150 to the bottom heat sink 120, thus removing heat from the cabin side air flow and making the space 30 cooler. In the Heating Mode, the chips 110 transfer heat from the bottom heat sink 120 to the top heat sink 150, thus adding heat to the cabin space 30 and making it warmer.
For example, the operation Intensity can be set at least as Mild or Intense. A variable intensity control on the hand held controller 950 determines how much electrical current is applied through the thermoelectric chips 110, thus determining how intensely the chips 110 transfer heat from one side to the other. In the Mild setting, the current is reduced (low duty cycle). In the Intense setting, the current is transferred continuously (100% duty cycle).
For example, the Fan Speed can be Low or High. A control switch on the hand held controller 950 determines the speed of the cabin side fans. The switch can be incremental. At the Low end, the current to fans is reduced using a lower duty cycle. At the High end, the current to fans is increased using a higher duty cycle (up to 100%).
The unit 1000 then checks a battery voltage to ensure there is enough power to run the last-time or designated mode of operation (Step 704). The unit 1000 turns on the external side fans and applies power to the thermoelectric module 100, and turns on the cabin side fans (Step 705). The Unit 1000 regulates temperature until shutdown by the user or until the battery voltage reaches a low voltage set-point (Step 706).
The electronic control and power module 200 is built on a PCB board. This is a multiple-layer PCB. The minimal traces in the internal two layers are power and ground. The line widths may vary following the industry practice to keep the lines the same width for all forks of the same line.
FIG. 8 is a simplified diagram of the TEC module 100 and an electronic control and power module 200 of the thermoelectric heat transferring unit 1000. As shown in FIG. 8, the electronic control and power module 200 uses an CPU 210 and an H-bridge circuit (including 4 transistors) to control (1) the direction of current flow through each of the TEC chips 110 based on an operating mode, and (2) a pulse-width duty cycle controls the current level based on intensity setting. The higher the output of the TEC chips 110, the higher the cooling capability of the TEC unit 1000. The output of the TEC chips 110 can be increased by increasing the driving voltage. Therefore, additional boost power supply may be provided to supply a higher drive voltage.
An H-bridge is an electronic circuit which enables a voltage to be applied across a load in either direction. The CPU 210 is a free scale semiconductor microcontroller with on-chip peripherals including two serial interfaces, an I2C interface, a keyboard interface, a 10 bit AID converter, two timers which can be configured to provide PWM signals, and 32 k EEPROM. This device also includes a BDM for debugging software.
On the right side of FIG. 8, four high-current power transistors, constituting the H-bridge, are operated in pairs depending on mode (cooling or heating). The transistors A1, A2 turn “ON” (while B1, B2 “OFF”) to make current flow from (+) connection to (−) connection of the TEC chips (cooling mode). The transistors B1, B2 turn “ON” (while A1, A2 “OFF”) to make current flow in the opposite direction through the TEC chips (heating mode). Besides controlling the mode of heating or cooling, the H-bridge is used to perform pulse width modulation so as to control intensity. The amount of current is determined by how long the transistors are switched on. FIGS. 9A-B are voltage supply diagrams from the electronic control and power module 200 to the TEC module 100. When set at “low intensity”, the transistors are “off” for most of the duty cycle (FIG. 9A). When set at “high/full intensity”, the transistors are switched on nearly 100% (FIG. 9B). The transistor has an internal Schottky diode to handle inductive loads (although the Peltier device is effectively a resistive load).
A firmware/software was developed to drive the printed circuit board which utilized H Bridges and sensors to provide cooling and heating by utilizing fans and heat sinks, via hardware monitoring, real-time clock, etc, thereby implementing the flow chart depicted in FIG. 7.
The firmware source code may be provided as assembly language with minimal comments (over 60 pages of assembly code with numerous entry points in the code to support branch operations and subroutines). The critical timing loops were to identify and extract timing such that a good assessment of the H bridge turn-on and turn-off timing margins could be made. The firm source code includes two files. The first file is HCSO8 assembly code and includes the main routine and numerous subroutines. The second file is an included file sourced by the first file at compilation, and it includes general-purpose register definitions (register addresses and configuration settings).
The first file contains memory map equates, variable definitions, text strings (message headers), interrupt vector table, the main routine and numerous subroutines. The main routine initializes the port registers (sets ports to be inputs or outputs), initializes the CPU configuration registers, and configures the serial communications interface (SCI). The file contains routines to configure and use Timer 1 Channel 0 (T1 CO), the internal analog-to-digital converter (ADC), serial port (SCI) and various I/O ports. The code uses the Computer Operating Properly (COP) timer. The COP timer ensures that the CPU will reset itself if the routine gets hung in infinite loop or unknown state.
The code defines a number of “heat” and “cool” subroutines that setup the timer (T1 CO) and set the I/O pins associated with LEDs on the hand held controller 950. There are routines identified as “heat_loop” and “cool_loop” that implement heating and cooling functions by applying current pulses to the Peltier device. Heating or cooling is determined by the direction of the current flow through the Peltier device, which is determined by the configuration of the H-Bridge. There are also routines associated with turning fans on and off and adjusting the speed of the fans.
The advantages of the TEC unit 1000 over conventional refrigeration cycle units at least include that (1) such a solid state system has no liquids that can leak, like Freon (which can be a suffocation hazard in a confined space), (2) very few moving parts—the only moving parts are the fans required to circulate air through the heat transfer module, (3) self contained (because the unit is one piece it can be easily installed in a standard sleeper cab), and (4) providing both cooling and heating without using additional connections or fuel sources.
The components of the present invention may be conveniently implemented using a conventional general purpose or a specialized component according to the teachings of the present disclosure, as will be apparent to those skilled in the art. Appropriate software coding can readily be prepared by skilled programmers based on the teachings of the present disclosure, as will be apparent to those skilled in the software art. The invention may also be implemented by the preparation of application specific integrated circuits or by interconnecting conventional component circuits, as will be readily apparent to those skilled in the art.
The principles, preferred embodiments, and modes of operation of the present invention have been described in the foregoing specification. However, the invention which is intended to be protected is not limited to the particular embodiments disclosed. The embodiments described herein are illustrative rather than restrictive. Variations and changes may be made by others, and equivalents employed, without departing from the spirit of the present invention. Accordingly, it is expressly intended that all such variations, changes and equivalents which fall within the spirit and scope of the present invention as defined in the claims, be embraced thereby.

Claims

1. A thermoelectric heat transferring unit for transferring heat between an enclosed space and outside of the enclosed space, comprising:

an outer casting;

a power supply;

a thermoelectric cooling and heating module;

an electronic control and power module;

fans;

an air intake duct facing towards an external side; and

an air return duct facing towards the external side,

wherein the thermoelectric cooling and heating module includes an upper air flow chamber arranged on the enclosed-space side, a lower air flow chamber arranged on the external side, and at least one array of thermoelectric chips sandwiched directly between the upper air flow chamber and the lower air flow chamber,

said upper air flow chamber has an air inlet and an air outlet communicating with the enclosed space, and said lower air flow chamber is connected with the air intake duct and the air return duct,

each of the chambers has a heat sink with heat sink fins and is connected to the array of thermoelectric chips, and

the electronic control and power module controls the heat to be transferred from said upper air flow chamber via the array of thermoelectric chips to said lower air flow chamber in a cooling mode, and controls the heat to be transferred from said lower air flow chamber via the array of thermoelectric chips to said upper air flow chamber in a heating mode.

2. The thermoelectric heat transferring unit according to claim 1, further comprising a power circuit breaker for the power supply.

3. The thermoelectric heat transferring unit according to claim 1, further comprising a thermal insulation material filled, in void spaces around the thermoelectric cooling and heating module.

4. The thermoelectric heat transferring unit according to claim 1, further comprising a user controller.

5. The thermoelectric heat transferring unit according to claim 1, wherein the power supply consists of batteries.

6. The thermoelectric heat transferring unit according to claim 5, further comprising an alternator that recharges the batteries.

7. The thermoelectric heat transferring unit according to claim 1, wherein the enclosed space is inside a sleeping area of a tractor.

8. The thermoelectric heat transferring unit according to claim 1, wherein the upper air flow chamber includes a divider which divides the upper air flow chamber into right and left sides.

9. The thermoelectric heat transferring unit according to claim 8, wherein the divider is a center ridge ¾ a length of the upper air flow chamber.

10. The thermoelectric heat transferring unit according to claim 1, wherein the air inlet and the air outlet of the upper air flow chamber are arranged on the same side surface of the upper air flow chamber.

11. The thermoelectric heat transferring unit according to claim 1, wherein the air inlet and the air outlet of the upper air flow chamber are arranged on two opposite side surfaces of the upper air flow chamber.

12. The thermoelectric heat transferring unit according to claim 1, further comprising a thermal insulation material filled in spaces in and around the thermoelectric cooling and heating module.

13. The thermoelectric heat transferring unit according to claim 1, wherein the electronic control and power module includes a microprocessor and an H-bridge circuit.

14. The thermoelectric heat transferring unit according to claim 13, wherein an H-bridge circuit includes four transistors, and the H-bridge circuit is configured to control selection of the heating mode or the cooling mode and to perform pulse width modulation for adjusting heating or cooling intensity.

15. The thermoelectric heat transferring unit according to claim 1, wherein one of the fans is provided on each of the air inlet and the air outlet of the upper air flow chamber, and

one of the fans is provided at where said lower air flow chamber is connected with the air intake duct and at where said lower air flow chamber is connected with the air return duct.

16. The thermoelectric heat transferring unit according to claim 15, wherein the electronic control and power module controls speeds of the fans.

17. A thermoelectric heat transferring unit for transferring heat between an enclosed space and outside of the enclosed space, comprising:

a thermoelectric cooling and heating module;

an electronic control and power module;

an air intake duct facing towards an external side; and

an air return duct facing towards the external side,

18. A method for transferring heat between an enclosed space and outside of the enclosed space, comprising:

providing a thermoelectric heat transferring unit including a thermoelectric cooling and heating module, an electronic control and power module, an air intake duct facing towards an external side, and an air return duct facing towards the external side, the thermoelectric cooling and heating module having an upper air flow chamber arranged on the enclosed-space side, a lower air flow chamber arranged on the external side, and at least one array of thermoelectric chips sandwiched directly between the upper air flow chamber and the lower air flow chamber, said upper air flow chamber having an air inlet and an air outlet communicating with the enclosed space, and said lower air flow chamber being connected with the air intake duct and the air return duct, each of the chambers having a heat sink with heat sink fins and is connected to the array of thermoelectric chips;

transferring the heat from said upper air flow chamber via the array of thermoelectric chips to said lower air flow chamber in a cooling mode; and

transferring the heat from said lower air flow chamber via the array of thermoelectric chips to said upper air flow chamber in a heating mode.