JPH045907B2 - - Google Patents

Description

[Detailed Description of the Invention] <Technical Field> The present invention relates to a control device for an engine-driven heat pump, and more specifically, it determines a target engine speed based on the deviation between a set temperature and a detected indoor temperature, and determines the engine speed. The present invention is configured to control an engine speed regulating mechanism so that the engine speed approaches the target rotation speed, and particularly relates to an antifreeze control in a heat exchanger of an indoor unit in a cooling operation mode.

<Prior art> Conventional control devices of this type include (i) those without anti-freeze means, (b) those that stop the operation of the entire system using an anti-freeze thermoswitch, and (c) those that do not have engine speed control for anti-freezing. There are various types: one that takes priority over indoor temperature control, one that performs engine speed control for anti-freezing but gives priority to indoor temperature control, etc.

By the way, each of the above conventional types has the following drawbacks.

(b) Condensed water on the surface of the indoor unit heat exchanger freezes, reducing the cooling capacity of the heat pump.

(b) The number of times the system starts and stops increases, leading to a decrease in efficiency, and the starter motor and battery for starting the engine tend to wear out prematurely.

(c) When the freezing state is approaching, the room temperature control may work to increase the output (increase the target rotational speed), and in that case, the freezing state will become closer.

(d)...Room temperature control is on the output lower side (target rotation speed lower side)
Even when the heat pump is working hard, there are cases where the antifreeze control lowers the target rotational speed by only a small specified amount, making it impossible to properly and quickly control the room temperature, and reducing the efficiency of the heat pump system.

<Object of the Invention> In view of the drawbacks of the conventional type, the present invention prevents freezing in the indoor unit heat exchanger to prevent a decrease in heat pump capacity due to freezing, and also provides appropriate room temperature control. The purpose is to make it possible.

<Configuration of the Invention> In order to achieve the above object, the present invention has the following features:
As clearly shown in the functional block diagram of the figure, there is a means b for detecting the temperature of the indoor unit heat exchanger a, and an engine c.
a rotation speed determination means d for determining whether or not the target rotation speed of the rotation speed exceeds the set rotation speed at that time; and a heat detected by the temperature detection means b in response to the excess determination output of the rotation speed determination means d. A frozen state determining means e that determines the frozen state of the heat exchanger a by comparing the exchanger temperature and a preset set temperature; The rotation speed setting means f lowers the rotation speed by a prescribed amount from the set rotation speed at that time and outputs the setting signal to the quick mechanism g.

<Function> According to the above configuration, basically priority is given to antifreeze control, and when the target rotation speed of engine c exceeds the set rotation speed and the temperature of heat exchanger a of the indoor unit exceeds the set temperature. If the target rotation speed of engine c does not exceed the set rotation speed, that is, when the indoor temperature control works to decelerate the engine, the rotation speed of engine c is lowered. Control operations are prohibited and priority is given to indoor temperature control.

<Example> Hereinafter, the present invention will be described in detail based on an example shown in the drawings.

FIG. 2 shows a schematic block diagram of the engine-driven heat pump and control device, and FIGS. 3 and 4 show control flowcharts.

The engine heat pump consists of an outdoor unit 1 and an indoor heat exchanger 2 as an indoor unit.The outdoor unit 1 includes an engine 3, a refrigerant compressor 4 driven by the engine 3, a condenser, Refrigerant circuit components such as expansion valves and evaporators; when water is used as a heat medium fluid, a group of heat exchangers for obtaining hot water or cold water as a heat medium fluid; a heat radiation fan;
A water pump for circulating hot and cold water to the indoor unit 2, a heat exchanger for recovering engine exhaust heat, and the like are incorporated.

In addition, a remote control switch 5 equipped with an air conditioning/heating switch, a temperature setting device, etc. is connected to the indoor unit, and an indoor temperature sensor 6 is connected to the indoor unit.
A temperature sensor 7 is provided in the heat exchanger of the indoor unit 2 as a temperature detection means. The engine 3 is equipped with an electronic governor 8 as a speed regulating mechanism. When the engine 3 is a gasoline engine or a gas engine, the electronic governor 8 is configured to adjust the opening of the throttle bar using an actuator such as a solenoid, and when the engine 3 is a diesel engine, the electronic governor 8 is configured to adjust the opening of the throttle bar using an actuator such as a solenoid. is operated by an actuator.

This heat pump controls the engine speed according to the required heat load, and this control is performed using a microcomputer 9. The microcomputer 9 is equipped with a CPU 10, a ROM 11, a RAM 12, and an input/output O port 13. It is connected via an A converter 14 and an A/D converter 15.

Next, the entire room temperature control operation using the microcomputer 9 will be explained chronologically with reference to the flowchart of FIG. Note that the same reference numerals are written in FIG. 3 corresponding to the respective step codes shown below.

() Indoor temperature Tm detected by temperature sensor 6
(°C) is sampled at fixed time intervals (1 minute in this example), and
The set temperature Tr (°C) set in is also read.

Note that the indoor temperature Tr can be replaced by the detected temperature of hot and cold water, which is the heat medium of the indoor unit 2.

() After the cooling/heating operation mode identification process, the deviation dT (°C) between the set temperature Tr and the sampled room temperature Tm is calculated.

() Based on this deviation dT, the target rotation speed Nt (rpm) of the engine is calculated from map data stored in the ROM 11 in advance.

() Anti-freeze control (described later) () After a certain period of time (10 seconds in this example) has elapsed after the target rotation speed Nt has been determined, if this target rotation speed Nt is not 0, the heat pump operation will continue and the target rotation speed will be reached. If the rotational speed Nt is 0, the process moves to the heat pump stop step. Note that stopping the heat pump means stopping the engine.

() Once it is decided to continue the heat pump operation,
The target rotation speed Nt and the current set rotation speed Nr (rpm) are compared.

() When the target rotation speed Nt is larger than the set rotation speed Nr, that is, when performing amplification control,
The new set rotation speed is set by adding the predetermined rotation speed (50 rpm in this example) to the current set rotation speed Nr.
Set to Nr.

Also, when the target rotation speed Nt is smaller than the set rotation speed Nr, that is, when performing deceleration control, the new set rotation speed is calculated by subtracting the predetermined rotation speed (50 rpm in this example) from the current set rotation speed Nr. Let it be Nr.

The operation of increasing or decreasing the set rotation speed by a predetermined rotation speed is repeated every 10 seconds until the set rotation speed matches the target rotation speed.

When the target rotation speed Nt becomes equal to the set rotation speed Nr, the set rotation speed Nr is directly set as the new set rotation speed Nr.

() In this way, the set rotation speed
Nr is compared with pre-stored map data to determine the electronic governor set voltage Vr (v).

() This electronic governor setting voltage Vr is output, and speed regulation is performed according to this voltage Vr.

FIG. 4 shows a flowchart of the anti-freeze control, and the operation thereof will be described below over time. Note that the same reference numerals are written in FIG. 4 corresponding to the respective step codes shown below.

() The target rotational speed Nt determined in step of the main routine is compared with the current set rotational speed Nr, and if the target rotational speed Nt is smaller than the set rotational speed Nr, this entire routine is passed. In other words, when the room temperature control is in the engine deceleration control state, this antifreeze control is prohibited.

() When the target rotation speed Nr is equal to or higher than the current set rotation speed Nt, the temperature Tcin (° C.) of the indoor heat exchanger detected by the temperature sensor 7 is read.

() The heat exchanger temperature Tcin read in this way is compared with the preset freezing warning setting temperature Tcinr (°C), and if the detected heat exchanger temperature Tcin is equal to or higher than the setting temperature Tcinr, no freezing occurs. When there is no danger, the system directly shifts to room temperature control.

() The detected heat exchanger temperature Tcin is the set temperature
If it is determined that the rotation speed is smaller than Tcinr and there is a risk of freezing, the target rotation speed Nt is set by a preset amount (in this example,
200rpm).

() Target rotation speed corrected in this way
Nt is the preset low rotation speed (in this example
900 rpm) or more, the room temperature control is performed based on this target rotation speed Nt.

() If the corrected target rotation speed Nt is smaller than the set rotation speed (900 rpm) Nr, the target rotation speed Nt is set to 0, the main routine is entered, and the engine is stopped.

<Effects of the Invention> As described above, according to the present invention, antifreeze control basically takes priority over room temperature control, so freezing in the indoor unit heat exchanger is reliably prevented, and freezing of the heat exchanger is prevented. In addition, when room temperature control is in engine deceleration control, antifreeze control is prohibited, so the reduction in target rotation speed for antifreeze control is suppressed. Problems such as a drop in the response of room temperature control have been eliminated, and room temperature control can now be performed through efficient heat pump operation.

[Brief explanation of drawings]

Fig. 1 is a functional block diagram showing the configuration of the present invention, Fig. 2 is a block diagram of one embodiment thereof, Fig. 3 is a flowchart showing the main routine of room temperature control, and Fig. 4 is a flowchart of the antifreeze control routine. It is a flowchart. 2... Indoor unit, 3... Engine, 7... Temperature sensor (heat exchanger temperature detection means), 8... Electronic governor (speed regulating mechanism), 9... Microcomputer.

Claims (1)

[Claims] 1. A target engine speed is determined according to the deviation between a set temperature and a detected indoor temperature, and an engine speed regulating mechanism is controlled so that the engine speed approaches the target speed. A control device for an engine-driven heat pump configured as follows: means for detecting the temperature of a heat exchanger of an indoor unit; and rotation speed determining means for determining whether a target rotation speed of the engine exceeds a set rotation speed at that time. and a freezing state in which a frozen state of the heat exchanger is determined by comparing the heat exchanger temperature detected by the temperature detecting means with a preset temperature in response to the excess determination output of the rotation speed determining means. A control device for an engine-driven heat pump, comprising: a determination means; and a rotation speed setting means for lowering the target rotation speed by a specified amount from the currently set rotation speed in response to a freeze determination output from the freeze state determination means.