Air conditioner heat pump system and engineering machinery

Abstract

The invention relates to an air-conditioning heat pump system for engineering machinery, which comprises a main circulation loop in which a working medium circulates, and a compressor assembly, an outdoor heat exchanger, an internal heat exchanger assembly, a main expansion valve and a switching valve component for switching the system between a heating mode and a cooling mode are arranged in the main circulation loop, the internal heat exchanger assembly comprises a first branch and a second branch which are connected in parallel, the first branch is provided with a first internal heat exchanger serving as an evaporator in a refrigeration mode, and the second branch is provided with a second internal heat exchanger serving as a condenser in a heat pump heating mode. A first one-way valve is connected to the downstream of the first internal heat exchanger on the first branch, and a second one-way valve is connected to the downstream of the second internal heat exchanger on the second branch. The invention further relates to engineering machinery with the air conditioner heat pump system.

Description

Technical Field

[0001] This invention relates to the field of engineering machinery technology, and more specifically to an air conditioning heat pump system for engineering machinery and engineering machinery having the air conditioning heat pump system. Background Technology

[0002] During the use of construction machinery, the working environment is often harsh, including high temperature, high humidity, dust, and high corrosiveness. This harsh working environment not only affects the work efficiency and health of personnel but also poses a serious threat to the stability, reliability, and lifespan of the machinery. Therefore, equipping construction machinery with an effective and reliable air conditioning heat pump system is essential.

[0003] Existing air conditioning heat pump systems for construction machinery have two modes: heating and cooling. In heating mode, heat absorbed from the outside air is released into the cab via refrigerant to heat the cab. In this mode, the air conditioning heat pump system functions as an air source heat pump, allowing for more energy-efficient cab heating. In cooling mode, heat absorbed from the cab air is released to the outside via refrigerant to cool the cab.

[0004] However, existing air conditioning heat pump systems have drawbacks for use in construction machinery, such as high energy consumption, high operation and maintenance costs, and relatively poor reliability. They need to be optimized to meet the high reliability requirements of construction machinery and its operating conditions and performance requirements.

[0005] Therefore, the present invention aims to overcome one or more of the above-mentioned problems. Summary of the Invention

[0006] To address the aforementioned problems, this invention proposes an improved air conditioning heat pump system that enhances system reliability, reduces system manufacturing, operating, control, and maintenance costs, and ensures its normal operation is not constrained by the working environment of construction machinery, making it suitable for various types of construction machinery and various work scenarios.

[0007] According to one aspect of the present invention, an air conditioning heat pump system for engineering machinery is provided, comprising a main circulation loop in which a working medium circulates, a compressor assembly, an outdoor heat exchanger, an internal heat exchanger assembly, and a main expansion valve located between the outdoor heat exchanger and the internal heat exchanger assembly, wherein a switching valve component configured to switch the air conditioning heat pump system between a heat pump heating mode and a cooling mode is connected between the compressor assembly and the outdoor heat exchanger and the internal heat exchanger assembly, characterized in that the internal heat exchanger assembly comprises a first branch and a second branch connected in parallel, a first internal heat exchanger serving as an evaporator in cooling mode is provided on the first branch, a second internal heat exchanger serving as a condenser in heat pump heating mode is provided on the second branch, a first one-way valve is connected downstream of the first internal heat exchanger on the first branch, wherein the flow direction of the working medium when the first one-way valve is forward-biased is consistent with the flow direction of the working medium when the first branch is activated, and a second one-way valve is connected downstream of the second internal heat exchanger on the second branch, wherein the flow direction of the working medium when the second one-way valve is forward-biased is consistent with the flow direction of the working medium when the second branch is activated.

[0008] The air conditioning heat pump system according to the present invention advantageously utilizes the configuration of a first check valve and a second check valve to switch between using a heat exchanger of appropriate design in different operating modes, thereby improving operational reliability, simplifying control, and reducing manufacturing and control costs.

[0009] Advantageously, the first and second check valves are mechanical check valves. Mechanical check valves are non-software controlled electronic types, avoiding the susceptibility of electronic valve components to corrosion from external dust on construction machinery, and the impact of power supply and control circuit fluctuations on electronic check valves. By employing this type of highly reliable mechanical check valve in the air conditioning heat pump system according to the invention, the use of the first and second check valves simplifies the control of switching between different operating modes and improves the operational reliability of the system.

[0010] In an advantageous embodiment, a third check valve is provided on the second branch upstream of the second internal heat exchanger. When the third check valve is forward-biased, the flow direction of the working medium is the same as the flow direction of the working medium when the second branch is activated. Advantageously, this third check valve is a mechanical check valve.

[0011] In an advantageous embodiment, a branch expansion valve is provided on the first branch upstream of the first internal heat exchanger. A bypass branch is connected in parallel at both ends of the main expansion valve. A fourth check valve is provided on the bypass branch. When the fourth check valve is in the forward direction, the upstream end of the bypass branch is fluidly connected to the outdoor heat exchanger, and the downstream end of the bypass branch is fluidly connected to the inlet of the branch expansion valve. Advantageously, the fourth check valve is a mechanical check valve. This makes the operation and control of the system in cooling mode more reliable.

[0012] In an advantageous embodiment, the air conditioning heat pump system includes a PTC auxiliary heating system configured for PTC heating, the PTC auxiliary heating system including an auxiliary circulation loop in which a liquid circulates, a PTC heater for heating the liquid and a radiator located downstream of the PTC heater, the radiator being configured to heat the airflow to be supplied to the interior of the passenger compartment by exchanging heat with the liquid heated by the PTC heater.

[0013] In an advantageous embodiment, the compressor assembly includes a compressor and a gas-liquid separator disposed on the inlet side of the compressor. Temperature and pressure sensors are installed at the inlet and outlet of the compressor to detect the compressor's suction and discharge temperatures, as well as suction and discharge pressures. By monitoring the pressure and temperature at the compressor's inlet and outlet, and the operating conditions of the main circulation loop, it is ensured that the suction superheat, discharge temperature, suction pressure, and discharge pressure are within the expected range. If the compressor's pressure or temperature exceeds the compressor's allowable operating pressure and temperature range, it will reduce speed or shut down, thereby better protecting the compressor and extending its service life.

[0014] In an advantageous embodiment, the air conditioning heat pump system includes a controller configured to activate only PTC heating in response to heating demand when the ambient temperature is below a preset value, and to activate a heat pump heating mode or a combined heating mode including both heat pump heating and PTC heating in response to heating demand when the ambient temperature is greater than or equal to the preset value. This eliminates the constraints of the operating environment of construction machinery, expanding the application scenarios of the air conditioning heat pump system.

[0015] In an advantageous embodiment, the controller is configured to control the compressor speed based on the difference between the set temperature and the actual temperature inside the cab. This allows for flexible adjustment to meet the heating or cooling needs of the cab.

[0016] In an advantageous embodiment, temperature and pressure sensors are located immediately upstream of the main expansion valve and the branch expansion valve. This allows for precise control of the operating conditions of the main circulation loop and the opening degree of the expansion valves, which helps ensure the reliable operation of the first and second internal heat exchangers.

[0017] In an advantageous embodiment, the preset value is -10°C. At this temperature, the system's main circulation loop cannot start due to the excessively low ambient temperature. The system controller can then activate the PTC heating mode to supply warm air to the cab.

[0018] According to another aspect of the present invention, an engineering machine is provided, which includes the above-described air conditioning heat pump system.

[0019] The air conditioning heat pump system according to the present invention is better suited to the operating environment of construction machinery and can better meet the cooling or heating needs of the cab, and its operation is more reliable (this is crucial for construction machinery, because once the air conditioning heat pump system fails, it may lead to personal injury or death, and in severe cases, it may cause work stoppage, project delays, and significant losses). In addition, the manufacturing cost, operating cost, control cost, and maintenance cost of the air conditioning heat pump system according to the present invention are greatly reduced. Attached Figure Description

[0020] The features and advantages of an example of the present invention will become apparent from the following detailed description and accompanying drawings, wherein:

[0021] Figure 1 A general schematic diagram of the main circulation loop of the air conditioning heat pump system according to the present invention in cooling mode is shown;

[0022] Figure 2 A general schematic diagram of the main circulation loop of the air conditioning heat pump system according to the present invention in heat pump heating mode is shown.

[0023] Figure 3 A schematic diagram of an air conditioning heat pump system according to the present invention in combined heating mode is shown, wherein the main circulation loop is in heat pump heating mode and the auxiliary circulation loop is in PTC heating mode; and

[0024] Figure 4 A three-dimensional structural schematic diagram and end view of the mechanical one-way valve used in the air conditioning heat pump system according to the present invention are shown.

[0025] List of reference numerals

[0026] 1-Air conditioning heat pump system; 10-Compressor assembly; 101-Compressor; 102-Gas-liquid separator; 101TP-First temperature and pressure sensor; 20-Outdoor heat exchanger; 20F-Fan; 30-Main expansion valve; 30L-Bypass branch; 30V4-Fourth check valve; 40-Internal heat exchanger assembly; 401-First branch; 402-Second branch; 40E-First internal heat exchanger; 40C-Second internal heat exchanger; 40F-Blower; 40V1-First check valve; 40V2-Second check valve; 40V3-Third check valve; 40TP-Second temperature and pressure sensor; 30TP-Third temperature and pressure sensor; 50-Switching valve assembly; 60-PTC auxiliary heating system; 601-PTC heater; 602-Radiator; 603-Pump; 604-Water supply tank; V-Mechanical check valve; VC-Cylinder. Detailed Implementation

[0027] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0028] It should be noted that the terms "comprising" and "having" and any variations thereof in the specification, claims and accompanying drawings of this invention are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are explicitly listed, but may include other steps or units that are not explicitly listed or that are inherent to such processes, methods, products or devices.

[0029] The terms "first," "second," etc., introduced in the description of this invention are for descriptive purposes only and should not be construed as indicating or implying relative importance. The directional terms "upstream" and "downstream," etc., indicate the upstream and downstream orientations relative to the direction of fluid flow in the branch or section of road when it is in use.

[0030] See Figure 1 As shown, the air conditioning heat pump system 1 for construction machinery according to the present invention includes a compressor assembly 10, an outdoor heat exchanger 20, a main expansion valve 30, and an internal heat exchanger assembly 40 fluidly connected by pipes, forming a main circulation loop in which a working medium (e.g., refrigerant R134a) circulates. In the illustrated embodiment, the compressor assembly 10 includes a compressor 101 and a gas-liquid separator 102 disposed on the inlet side of the compressor. The gas-liquid separator 102 is configured to separate the gaseous and liquid portions of the refrigerant, preventing the liquid portion from entering the compressor and causing impact, thus providing effective protection for the compressor. First temperature and pressure sensors 101TP are provided at the compressor inlet and outlet. Advantageously, the compressor is also provided with a speed sensor (not shown) for detecting its rotational speed.

[0031] A switching valve component 50 is connected between the compressor assembly 10 and the outdoor heat exchanger 20 and the internal heat exchanger assembly 40. The switching valve component 50 selectively changes the flow order of the working medium in the main circulation loop through the outdoor and internal heat exchanger assemblies, thereby enabling the air conditioning heat pump system to switch between cooling mode and heat pump heating mode (described in detail later). In the illustrated embodiment, the switching valve component 50 is a four-way reversing valve.

[0032] The main expansion valve 30 is located between the outdoor heat exchanger 20 and the internal heat exchanger assembly 40. It is used to throttle the high-temperature and high-pressure refrigerant discharged from the heat exchanger, which is used as a condenser, so that it becomes a low-pressure and low-temperature refrigerant.

[0033] like Figure 1 or Figure 2 As shown, the internal heat exchanger assembly 40 includes a first branch 401 and a second branch 402 connected in parallel. A first internal heat exchanger 40E is installed on the first branch 401, and a second internal heat exchanger 40C is installed on the second branch. The first branch and the second branch are connected to the main circulation loop at their confluence points via a T-junction.

[0034] The first branch / first internal heat exchanger is activated in response to the cooling demand of the air conditioning heat pump system. For example... Figure 1 As shown, when the first branch 401 is activated, the working medium flows through the first branch 401 in the direction of arrow A. A first check valve 40V1 is connected downstream of the first internal heat exchanger 40E on the first branch. When the first check valve 40V1 is forward-biased, the fluid flow direction is the same as that of arrow A. A branch expansion valve 40EV is installed on the first branch 401 upstream of the first internal heat exchanger 40E. A second temperature and pressure sensor 40TP is installed immediately upstream of the branch expansion valve.

[0035] The second branch / second internal heat exchanger is activated in response to the heat pump heating demand of the air conditioning heat pump system. For example... Figure 2 As shown, when the second branch 402 is activated, the working medium flows through the second branch 402 in the direction of arrow B. A second check valve 40V2 is connected downstream of the second internal heat exchanger 40C on the second branch. When the second check valve 40V2 is forward-biased, the fluid flow direction is the same as that of arrow B. In the illustrated embodiment, the first check valve 40V1 and the second check valve 40V2 are mechanical check valves. A third check valve 40V3 is provided upstream of the second internal heat exchanger 40C on the second branch 402. Advantageously, this third check valve is a mechanical check valve. When the third check valve 40V3 is forward-biased, the liquid flow direction is the same as that of arrow B.

[0036] A fan 20F is located near the outdoor heat exchanger 20 to circulate ambient air through the outdoor heat exchanger for heat exchange with the working medium flowing within it. A blower 40F is located near the internal heat exchanger assembly 40. The blower 40F forces airflow through either the first internal heat exchanger 40E or the second heat exchanger 40C. The heated or cooled airflow is supplied to the cab (not shown) to meet heating and cooling requirements.

[0037] In the illustrated embodiment, a bypass branch 30L is connected in parallel across the two ends of the main expansion valve 30, and a fourth check valve 30V4 is installed on this bypass branch. Advantageously, the fourth check valve 30V4 is a mechanical check valve. In cooling mode, the bypass branch 30L is activated, and the fourth check valve 30V4 is forward-biased. When the fourth check valve is forward-biased, the liquid flow direction is consistent with the direction of arrow C. The upstream end of the bypass branch 30L is fluidly connected to the outdoor heat exchanger 20, and the downstream end of the bypass branch 30L is fluidly connected to the inlet of the branch expansion valve 40EV. In heat pump heating mode, the main expansion valve 30 is activated, wherein the working medium flows through the main expansion valve in the direction of arrow D. A third temperature and pressure sensor 30TP is installed immediately upstream of the main expansion valve (or near the inlet of the main expansion valve).

[0038] The air conditioning heat pump system according to the present invention includes a controller (not shown). The controller is connected to all sensor elements, the main expansion valve, and branch expansion valves, etc.

[0039] like Figure 1As shown, in response to cooling demand, the switching valve component 50 is in the first valve position, in which the compressor outlet is fluidly connected to the outdoor heat exchanger 20, and the internal heat exchanger assembly 40 (essentially the first internal heat exchanger 40E) is fluidly connected to the inlet of the gas separator 102. Under the action of the compressor 101, a high-temperature, high-pressure refrigerant flow is formed, which then enters the outdoor heat exchanger 20, releasing heat to the outdoor airflow. At this time, the outdoor heat exchanger acts as a condenser. The controller controls the main expansion valve to be closed and controls the branch expansion valve 40EV to be open. The refrigerant flowing out of the outdoor heat exchanger 20 enters the bypass branch 30L, opens the fourth one-way valve 30V4, and flows into the internal heat exchanger assembly. Due to the flow obstruction effect of the second one-way valve 40V2, the refrigerant flow is not allowed to flow into the second internal heat exchanger. The refrigerant flow into the first branch 401 is throttled, cooled, and depressurized by the branch expansion valve 40EV, and then enters the first internal heat exchanger 40E. In the first internal heat exchanger 40E, the refrigerant evaporates and absorbs heat, thus cooling the airflow generated by the blower. The cooled airflow is then supplied to the cab to meet its cooling requirements. The refrigerant flow out of the first internal heat exchanger pushes open the first one-way valve 40V1 and enters the switching valve assembly 50. Because the pressure in the pipeline between the third one-way valve 40V3 and the second internal heat exchanger 40C on the second branch 402 is higher than the refrigerant pressure flowing out of the first internal heat exchanger 40E on the first branch, the refrigerant flow from the first one-way valve 40V1 in the first branch 401 cannot push open the third one-way valve 40V3 to enter the second internal heat exchanger 40C. Therefore, the second internal heat exchanger in the second branch is not activated at this time. With the switching valve component 50 in the first valve position, the refrigerant entering the switching valve component flows into the gas-liquid separator 102 through the corresponding connecting passage, and then flows into the compressor 101 after gas-liquid separation. After compression, it forms a high-temperature, high-pressure refrigerant flow, which is then discharged from the compressor. This cycle repeats continuously. As a result, cold air is continuously supplied to the cab, cooling the interior of the cab.

[0040] In an optional embodiment, the third check valve can be omitted. In this case, even if some refrigerant flows into the second branch, the pressure of this refrigerant decreases after passing through the second internal heat exchanger, significantly less than the back pressure of the second check valve 40V2. Therefore, combined with the bias pressure of the second check valve itself, the second check valve cannot switch to the open state. To completely prevent refrigerant from flowing into the second internal heat exchanger in this cooling mode, the third check valve is preferably provided. This configuration also prevents lubricating oil from depositing in the second branch or the second internal heat exchanger.

[0041] In heat pump heating mode, such as Figure 2As shown, the switching valve component 50 is in the second valve position. In this second valve position, the compressor's discharge port is connected to the internal heat exchanger assembly 40, and the outdoor heat exchanger 20 is connected to the inlet of the gas-liquid separator 102. At this time, the controller controls the main expansion valve 30 to be in the open state and controls the branch expansion valve 40EV to be in the closed state. The high-temperature, high-pressure refrigerant discharged from the compressor flows into the second branch 402, pushes open the third one-way valve 40V3, and flows into the second internal heat exchanger 40C. Due to the flow obstruction effect of the first one-way valve 40V1, the high-temperature, high-pressure refrigerant is not allowed to enter the first internal heat exchanger. The refrigerant flow through the second internal heat exchanger 40C releases heat, causing the airflow flowing through the second internal heat exchanger to heat up. The heated airflow can be supplied to the driver's cab for heating. The refrigerant flow from the second internal heat exchanger pushes open the second one-way valve 40V2, flows out of the internal heat exchanger assembly, and enters the main expansion valve 30. Because the branch expansion valve 40EV is closed, the refrigerant flowing from the second internal heat exchanger 40C cannot flow into the first internal heat exchanger. The refrigerant flow entering the main expansion valve 30 is cooled and depressurized by the throttling effect of the main expansion valve and enters the outdoor heat exchanger 20. During its flow through the outdoor heat exchanger 20, it absorbs heat from the airflow flowing through it, and the refrigerant flow that has absorbed heat and evaporated enters the switching valve component 50 in the second valve position. It then enters the gas-liquid separator 102 through the corresponding connecting passage in the switching valve component, where the gaseous and liquid refrigerants are separated. The gaseous refrigerant is supplied to the compressor 101 for compression, forming a high-temperature, high-pressure refrigerant, which is then discharged from the compressor. This cycle repeats continuously. As a result, warm air is continuously supplied to the driver's cabin to meet the heating needs.

[0042] The aforementioned heat pump heating mode can only be activated when the outdoor ambient temperature is within a suitable range, such as when the outdoor temperature is greater than or equal to a preset value (e.g., -10°C). At excessively low outdoor temperatures, using ambient air as a heat source makes selecting the operating conditions for the main circulation loop extremely difficult and inefficient. In this case, the controller can activate only the PTC (Positive Temperature Coefficient) auxiliary heating system of the air conditioning heat pump system for PTC heating, disabling the operation of the main circulation loop.

[0043] See Figure 3As shown, the PTC auxiliary heating system 60 includes an auxiliary circulation loop in which liquid circulates. Here, the liquid may be, for example, antifreeze. A PTC heater 601 for heating the liquid and a radiator 602 located downstream of the PTC heater are provided in the auxiliary circulation loop. A pump 603 is used to pump the liquid to circulate in the auxiliary circulation loop. An expansion tank / makeup tank 604 is provided at the pump inlet to accommodate the expansion of the liquid in the auxiliary circulation loop, and also serves to maintain pressure and make up for system water. When the PTC heater 601 is activated, the liquid heated by the PTC heater flows through the radiator 602, where it exchanges heat with the airflow driven by the blower 40F, causing the airflow to heat up. This heated airflow can be delivered to the driver's cab for heating.

[0044] When the outdoor ambient temperature is above, for example, -10°C but still below, and heating is required, the controller sends an activation command to the system, activating the heat pump heating mode in the main circulation loop. However, if the warm air obtained solely through the heat pump heating mode in the main circulation loop is insufficient to meet the heating needs of the driver's cabin, both PTC heating and heat pump heating can be activated simultaneously (i.e., a combined heating mode including both heat pump and PTC heating is activated). See also Figure 3 As shown, the main circulation loop is in heat pump heating mode, and the PTC heater 601 in the PTC auxiliary heating system is energized. At this time, the blower 40F forces the airflow through the second internal heat exchanger 40C and radiator 602 and heats it up. The heated airflow is then supplied to the cab for heating.

[0045] Although the diagram shows airflow passing sequentially through the first internal heat exchanger, the second internal heat exchanger, and the radiator arranged in a row, it can be understood that, in order to reduce airflow resistance, the airflow can be selectively directed through the corresponding heat exchangers in different operating modes by means of damper design.

[0046] In an optional embodiment, the branch expansion valve on the first branch can be moved to a position downstream of the fourth check valve on the bypass branch. In this configuration, when switching to cooling mode, the refrigerant flows through the bypass branch 30L, is throttled by the branch expansion valve, and enters the first internal heat exchanger on the first branch 401, thereby enabling the first internal heat exchanger to function as an evaporator. When switching to heat pump heating mode, the branch expansion valve closes. The high-temperature, high-pressure refrigerant discharged from the compressor enters the second branch 402, flows through the second internal heat exchanger, releases heat, and then flows into the main expansion valve. At this time, due to the pressure loss in the pipeline and the high back pressure, the refrigerant flow cannot push open the first check valve to open the first branch.

[0047] In other words, the branch expansion valve can optionally be located on the bypass branch. To improve control accuracy, the branch expansion valve is preferably located very close to the inlet of the evaporator. That is, the branch bypass valve 40EV is preferably located immediately upstream of the first internal heat exchanger 40E, which serves as the evaporator.

[0048] As shown in the figure, temperature and pressure sensors are installed at the main expansion valve 30 and the branch expansion valve 40EV. These temperature and pressure sensors are connected to the controller to monitor the opening degree of the expansion valves and thus control the operating pressure of the system.

[0049] Although the diagram shows a bypass branch 30L, a fourth one-way valve 30V4, and a branch expansion valve 40EV that are activated in cooling mode, it is understandable that these components could be omitted, and only the main expansion valve 30 could be used to achieve refrigerant throttling (cooling and pressure reduction) in both cooling and heat pump heating modes. However, doing so would result in a decrease in the system's control accuracy and operational reliability.

[0050] exist Figure 1-3 In the illustrated embodiment, the first check valve 40V1, the second check valve 40V2, the third check valve 40V3, and the fourth check valve 30V4 are all configured as mechanical check valves. Figure 4 As shown, the mechanical check valve V has a simple cylinder VC and a ball (valve disc) located inside the cylinder, pressed against the through-hole area by a bias spring. This type of check valve belongs to the automatic valve category, has a simple structure, reliable operation, and does not require electronic or electrical control or software programming for on / off control. The opening pressure threshold of the mechanical check valve is preset solely by the biasing force of the bias spring.

[0051] While electronic check valves offer flexible control, integrating them requires software-controlled switching. If the program malfunctions, necessary switching actions may not be executed. Furthermore, the working environment of construction machinery is corrosive, subject to large temperature differences, high mechanical shock, and high vibration. The increased number of electronic control components raises the probability of failure. Mechanical check valves, installed in the main circulation loop, are unaffected by the working environment of construction machinery and do not require integration into control software, significantly improving system reliability. This completely avoids the drawbacks of electronic check valves, such as high electrical failure rates, high control costs, control malfunctions, and poor reliability.

[0052] The air conditioning heat pump system according to the present invention employs a mechanical check valve to activate or deactivate the first and second branches, effectively ensuring the normal operation of the heat pump in heating and cooling modes, as well as the switching between these modes. The highly reliable mechanical check valve contributes to the high reliability of the entire system.

[0053] To further improve system reliability, first temperature and pressure sensors 101TP are installed at the inlet and outlet of compressor 101 to detect the compressor's suction and discharge temperatures, as well as suction and discharge pressures, and monitor the compressor's operating status. If the compressor's pressure or temperature exceeds the allowable operating pressure and temperature range, control commands, such as speed reduction or shutdown commands, can be sent to the compressor to better protect it and extend its service life.

[0054] This ensures that the compressor operates under suitable conditions (e.g., compressor discharge temperature ≤ 120°C, compressor suction pressure ≥ 0.16 MPa in cooling mode, compressor suction pressure ≥ 0.06 MPa in heat pump heating mode, and compressor suction superheat ≥ 5 K ≤ 15 K). Furthermore, it ensures that the maximum pressure of the air conditioning heat pump system does not exceed the limit (e.g., 3 MPa). This protects the entire system and the compressor, and also improves the system's operational reliability.

[0055] Furthermore, the controller is configured to control the compressor speed based on the difference between the set temperature and the actual temperature inside the cab, for example, using a PID (Proportional-Integral-Derivative) algorithm. This allows for real-time temperature control within the cab. The actual temperature inside the cab can be measured by a temperature sensor. The set temperature inside the cab is set by the driver using a control device according to their needs.

[0056] This invention also relates to construction machinery, such as loaders or excavators, equipped with the aforementioned air conditioning heat pump system. An outdoor heat exchanger is installed on the machine away from the cab. An internal heat exchanger assembly is installed in an air duct near the cab. These construction machines operate in extremely harsh environments, such as above 40°C or below -10°C. Operators in the cab utilize the air conditioning heat pump system to adjust the temperature inside the cab as needed to achieve a comfortable operating environment. The increased reliability of the air conditioning heat pump system can also increase the operating time of construction machinery operators, thereby accelerating project progress.

[0057] Industrial applicability

[0058] To facilitate understanding of the present invention, the working principle of the air conditioning heat pump system illustrated in the present invention will be explained below:

[0059] The air conditioning heat pump system according to the present invention switches in response to the cooling or heating needs of the personnel working in the driver's cab.

[0060] In response to cooling demand, the controller sends a switching command to the switching valve component, switching it to the first valve position (e.g., Figure 1(As shown). Simultaneously, the controller controls the main bypass valve to be closed and the branch bypass valve to be open. Refrigerant discharged from the compressor outlet flows into the outdoor heat exchanger, dissipates heat to the outdoor air, then flows into the bypass branch, passes through the fourth one-way valve, and enters the first branch. Throttled by the branch expansion valve, it enters the first internal heat exchanger, where it evaporates and absorbs heat, lowering the temperature of the airflow to be supplied to the driver's compartment. Next, the refrigerant flow pushes open the first one-way valve, enters the switching valve assembly, and flows into the gas-liquid separator. After gas-liquid separation, the gaseous refrigerant flows into the compressor inlet for compression. Thus, the entire air conditioning heat pump system, through the activation of the bypass branch and the first branch, forms a closed refrigeration cycle, continuously supplying low-temperature airflow to the driver's compartment.

[0061] When the ambient temperature is detected to be below, for example, -10°C, in response to heating demand, the controller sends an activation command to the PTC auxiliary heating system, actuating the pump to power the PTC heater. The antifreeze circulating in the PTC auxiliary heating system, heated by the PTC heater, flows into the radiator, transferring heat to the airflow to be supplied to the cab, thereby heating the cab.

[0062] When the ambient temperature is above, for example, -10°C but below, for example, 10°C, the controller determines whether to activate heat pump heating and / or PTC heating based on specific heating needs or the amount of electricity stored in the energy storage device. The air conditioning heat pump system according to the present invention can be switched to heat pump heating mode to function as an air source heat pump for heating the passenger compartment. Specifically, the switching valve component is switched to the second valve position (e.g., Figure 2 (As shown). The high-temperature, high-pressure refrigerant discharged from the compressor flows into the second branch, pushes open the third one-way valve, and enters the second internal heat exchanger. In the second internal heat exchanger, the refrigerant transfers heat to the airflow to be supplied to the cab, thereby providing warm air to the cab. The refrigerant flow through the second internal heat exchanger and the second one-way valve enters the main expansion valve, where it is throttled to form a low-temperature, low-pressure refrigerant flow. This refrigerant flow enters the outdoor heat exchanger, evaporates and absorbs heat, then enters the switching valve component and flows into the gas-liquid separator. After gas-liquid separation, the gaseous refrigerant enters the compressor for compression, forming a high-temperature, high-pressure refrigerant. This cycle continues, continuously supplying warm air to the cab. When the PTC auxiliary heating system is activated, the heat transferred via the radiator is also carried into the cab by the airflow, providing additional heating to the cab.

[0063] Therefore, the first check valve reliably ensures that no refrigerant flows into the first internal heat exchanger during heat pump heating mode. The second check valve reliably ensures that no refrigerant flows into the second internal heat exchanger during cooling mode.

[0064] For construction machinery, the first internal heat exchanger is primarily designed for applicable refrigeration conditions. Typically, the refrigerant pipes in the first internal heat exchanger are designed to be vertically positioned to facilitate the discharge of condensate outside the pipes. The second internal heat exchanger is primarily designed for applicable heating conditions. Typically, the refrigerant pipes in the second internal heat exchanger are designed to be horizontally positioned to improve heat exchange efficiency. Therefore, in this invention, by means of a first one-way valve and a second one-way valve, it is advantageous to switch the internal heat exchanger assembly to the appropriate operating mode in response to refrigeration or heating demands, thereby improving the utilization rate of both the first and second internal heat exchangers and ensuring that their pre-designed optimal heat exchange capacity is achieved.

[0065] The above description is merely of exemplary embodiments according to the present invention. The system according to the present invention is not limited to the specific embodiments described herein. Throughout this specification, references to “an example,” “another example,” “example,” etc., mean that a certain element / component (e.g., feature, structure, and / or characteristic) associated with the example is included in at least one example described herein, and may appear and / or may not appear in other examples. Furthermore, it is understood that multiple elements of any example described may be combined in any suitable manner in multiple different examples unless the context explicitly states otherwise.

[0066] This specification uses examples to disclose the invention, including preferred embodiments, and enables any person skilled in the art to implement the invention. The patentable scope of the invention is defined by the claims, but may include other examples that may be conceived by a person skilled in the art. Such other examples should fall within the scope of the claims if they have structural elements that are not distinct from the literal language of the claims, or if they include equivalent structural elements that are not substantially distinct from the literal language of the claims.

Claims

1. An air conditioning heat pump system for construction machinery, comprising a main circulation loop in which a working medium circulates, a compressor assembly, an outdoor heat exchanger, an internal heat exchanger assembly, and a main expansion valve located between the outdoor heat exchanger and the internal heat exchanger assembly, wherein a switching valve component configured to switch the air conditioning heat pump system between a heat pump heating mode and a cooling mode is connected between the compressor assembly and the outdoor and internal heat exchanger assemblies, characterized in that, The internal heat exchanger assembly includes a first branch and a second branch connected in parallel. A first internal heat exchanger, which functions as an evaporator in cooling mode, is installed on the first branch. A second internal heat exchanger, which functions as a condenser in heat pump heating mode, is installed on the second branch. A first check valve is connected downstream of the first internal heat exchanger on the first branch. When the first check valve is forward-biased, the flow direction of the working medium is the same as when the first branch is activated. A second check valve is connected downstream of the second internal heat exchanger on the second branch. When the second check valve is forward-biased, the flow direction of the working medium is the same as when the second branch is activated.

2. The air conditioning heat pump system according to claim 1, characterized in that, The first check valve and the second check valve are mechanical check valves.

3. The air conditioning heat pump system according to claim 1 or 2, characterized in that, A third check valve is installed upstream of the second internal heat exchanger on the second branch. When the third check valve is in the forward direction, the flow direction of the working medium is the same as the flow direction of the working medium when the second branch is activated.

4. The air conditioning heat pump system according to claim 3, characterized in that, The third check valve is a mechanical check valve.

5. The air conditioning heat pump system according to claim 4, characterized in that, A branch expansion valve is installed upstream of the first internal heat exchanger on the first branch. A bypass branch is installed in parallel at both ends of the main expansion valve. A fourth check valve is installed on the bypass branch. When the fourth check valve is in the forward direction, the upstream end of the bypass branch is fluidly connected to the outdoor heat exchanger and the downstream end of the bypass branch is fluidly connected to the inlet of the branch expansion valve.

6. The air conditioning heat pump system according to claim 5, characterized in that, The fourth check valve is a mechanical check valve.

7. The air conditioning heat pump system according to claim 5 or 6, characterized in that, The air conditioning heat pump system includes a PTC auxiliary heating system configured for PTC heating. The PTC auxiliary heating system includes an auxiliary circulation loop in which a liquid circulates. In the auxiliary circulation loop, a PTC heater for heating the liquid and a radiator located downstream of the PTC heater are provided. The radiator is configured to heat the airflow to be supplied to the interior of the passenger compartment by exchanging heat with the liquid heated by the PTC heater.

8. The air conditioning heat pump system according to claim 7, characterized in that, The compressor assembly includes a compressor and a gas-liquid separator disposed on the inlet side of the compressor. Temperature and pressure sensors are disposed at the inlet and outlet of the compressor to detect the compressor's suction temperature and discharge temperature, as well as suction pressure and discharge pressure.

9. The air conditioning heat pump system according to claim 8, characterized in that, The air conditioning heat pump system includes a controller configured to activate only PTC heating in response to heating demand when the ambient temperature is below a preset value, and to activate heat pump heating mode or a combined heating mode including both heat pump heating and PTC heating in response to heating demand when the ambient temperature is greater than or equal to the preset value.

10. The air conditioning heat pump system according to claim 9, characterized in that, The controller is configured to control the compressor speed based on the difference between the set temperature and the actual temperature inside the cab.

11. The air conditioning heat pump system according to claim 10, characterized in that, Temperature and pressure sensors are installed immediately upstream of the main expansion valve and the branch expansion valve.

12. The air conditioning heat pump system according to claim 9, characterized in that, The preset value is -10℃.

13. An engineering machinery, characterized in that, The air conditioning heat pump system includes any one of claims 1-12.

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