BACKGROUND OF THE INVENTION
Field of the Invention
[0001] The present invention relates to an engine driven heat pump.
Related Art
[0002] Conventionally, there is well known an engine driven heat pump having a construction
for driving a compressor by an engine. In the engine driven heat pump, the compressor
is connected to the engine via a clutch. In other words, the compressor transmits
or releases a driving power of the engine by an ON/OFF operation of the clutch.
[0003] There is also well known a technology of a compressor lock detection means. Compressor
lock means an abnormal state where compression mechanism of the compressor is not
movable due to liquid compression, rising of oil or incorporation of foreign material.
When the compressor lock is caused, it is necessary that all devices of the engine
driven heat pump are stopped, so as to repair and replace the compressor. In other
words, the compressor lock is the abnormal state (urgent abnormality) having a great
need for maintenance and repair, unlike another abnormal states (such as engine accident
fire).
[0004] JP1994-213171 discloses a control technology that detects whether the compressor lock is caused
under pressure condition after the elapse of a certain period of time after starting.
However, in a high-capacity engine driven heat pump, a plurality of compressors are
connected to one engine. The control technology disclosed in
JP 1994-213171, when applied to an engine driven heat pump having a plurality of compressors, is
disadvantageous in that there is a possibility of being unable to detect whether the
compressors are locked or not during starting of an air conditioning operation, as
it normally becomes a given pressure unless the compressor firstly driven during the
engine driven heat pump start-up is locked.
Briefly, in the engine driven heat pump, one compressor is continuously operated on
condition that it remains locked. As a result, when engaging the clutch so as to transmit
the driving power to the compressor on a locked condition, spark is sometimes generated
due to clutch slippage.
[0005] In the engine driven heat pump having the plurality of compressors, the construction
that transmits the driving power to one or plurality of compressors less than the
volume on board at the starting has a possibility of being unable to assuredly avoid
the starting of the air conditioning operation with the compressor on the locked condition,
at the starting of the air conditioning operation.
Disclosure of Invention
Problems to Be Solved By the Invention
[0006] It's an object of the present invention to provide an engine driven heat pump having
a plurality of compressors, capable of avoiding the starting of the air conditioning
operation with the compressor on the locked condition.
SUMMARY OF THE INVENTION
Means for Solving the Problem
[0007] In an engine driven heat pump of the present invention, which is an engine driven
heat pump having a plurality of compressors via clutches for the compressors, a slippage
generating torque of the clutches for the compressors is set up to be starting torque
of the engine or higher, and all of the clutches for the compressors are engaged,
at the time of starting the engine driven heat pump.
[0008] In the engine driven heat pump of the present invention, it is preferable to disengage
at least one of the clutches for the compressors after finishing a starting of the
engine.
Effect of the Invention
[0009] According to the engine driven heat pump of the present invention, in the engine
driven heat pump having a plurality of compressors, it can be assuredly detected whether
the compressor on the locked condition at the starting of the air conditioning operation
is present or not. More specifically, although the construction that transmits the
driving power to all of the compressors at the starting also transmits the driving
power to the compressor on the locked condition, the operation is locked without causing
the clutch slippage since the starting torque is the slippage generating torque of
the clutch or lower, whereby the engine driven heat pump is not driven with the compressor
on the locked condition. As the causes why the operation is locked are limited to
(1) the compressor lock, (2) abnormality of a starter and so on, an operator can easily
specify the compressor lock when it is generated.
[0010] According to the engine driven heat pump of the present invention, driving for controlling
compressor capacity corresponding to air-conditioning load can be performed, by disengaging
at least one of the clutches for the compressors.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011]
Fig. 1 is a diagram of a lateral construction illustrating driving construction of
a compressor according to an embodiment of the present invention.
Fig. 2 is a diagram of a cross section structure along the line AA' in Fig. 1 according
to an embodiment of the present invention.
Fig. 3 is a flow diagram illustrating a flow of a compressor lock detection control.
Fig. 4 is a graph chart illustrating a sequence when determined that the compressor
is locked according to an embodiment of the present invention.
Fig. 5 is a graph chart illustrating a sequence when determined that the compressor
is normal according to an embodiment of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0012] Next, embodiments of the present invention will be described.
Fig. 1 is a diagram of a lateral construction illustrating driving construction of
a compressor according to an embodiment of the present invention. Fig. 2 is a diagram
of a cross section structure along the line AA' in Fig. 1 according to an embodiment
of the present invention. Fig. 3 is a flow diagram illustrating a flow of a compressor
lock detection control. Fig. 4 is a graph chart illustrating a sequence when determined
that the compressor is locked according to an embodiment of the present invention.
Fig. 5 is a graph chart illustrating a sequence when determined that the compressor
is normal according to an embodiment of the present invention.
[0013] A driving construction of a compressor 10 in an engine driven heat pump 1 will be
briefly described, with reference to Fig. 1.
As shown in Fig. 1, an engine 2 is connected to the compressor 10 via a belt 5.
The engine 2 is disposed on an installation board 3 via an elastic member or the like
aimed at vibration insulation and sound insulation, and is incorporated into a casing
of the engine driven heat pump 1. The engine 2 includes a starter 6 for starting the
engine. The engine 2 includes an engine pulley 4 on an output shaft.
[0014] The compressor 10 includes a compressor pulley 11, an intake pipe 15 and a discharge
pipe 16, and is incorporated into the casing of the engine driven heat pump 1 as with
the engine 2. An input shaft 14 of the compressor 10 is rotatably driven by the driving
transmission of the compressor pulley 11 via the belt 5 due to the engine pulley 4.
The compressor 10 compresses an intake gas refrigerant at low temperature and low
pressure inhaled from the intake pipe 15 into a discharge gas refrigerant at high
temperature and high pressure, by rotating a scroll compression mechanism 13 due to
the input shaft 14, and discharges the gas refrigerant from the discharge pipe 16.
[0015] An electromagnetic clutch 20 is interposed between the input shaft 14 and the compressor
pulley 11 as a clutch for the compressor. The electromagnetic clutch 20 includes a
coil 17 provided integral with (attached and fixed to the inside of, in the present
embodiment,) the compressor pulley 11 and an armature 12 engaged to one end of the
input shaft 14 (that does not relatively rotate with respect to the input shaft 14
and that is slidable in the axial direction of the input shaft 14).
[0016] An Electronic Control Unit (hereinafter, referred to as ECU 7) is connected to the
respective systems and detection means (such as an ignition device, a temperature
detection means and a rotation speed detection means 18) of the engine 2, the respective
devices and detection means (an electronic expansion valve, an electromagnetic valve,
a temperature detection means, a pressure detection means) of the engine drive heat
pump 1 as well as the electromagnetic clutch 20, so as to control the operation of
the engine drive heat pump 1.
[0017] Moreover, the construction of the engine drive heat pump 1 equipped with two compressors
10 in one engine 2 will be briefly described, with reference to Fig. 2.
As shown in Fig, 2, the engine drive heat pump 1 of the present embodiment includes
two compressors 10 of the first compressor 10a and the second compressor 10b. The
belt 5 is provided and pulled so as to form as an approximately triangle with respect
to the pulley 4 and the compressor pulleys 11a, 11b.
[0018] An ON/OFF action of the electromagnetic clutch 20 for driving the compressor 10 having
the above construction will be described.
When the electromagnetic clutch 20 is engaged, the ECU 7 applies the current to the
coil 17 provided inside of the compressor pulley 11 so as to excite it. The armature
12 slides and absorbs to the side of the compressor pulley 11, due to flux generated
in the coil 17 of the compressor pulley 11. The armature 12 and the compressor pulley
11 become unified due to frictional engagement. Briefly, the electromagnetic clutch
20 is engaged, and the input shaft 14 of the compressor 10 is rotatably driven, so
as to put the compressor 10 into operation.
Meanwhile, when the electromagnetic clutch 20 is disengaged, i.e., when the coil 17
is not excited, the armature 12 and the compressor pulley 11 are separated across
a gap, and the compressor pulley 11 only ticks over. Briefly, the electromagnetic
clutch 20 is disengaged, and the driving power of the engine 2 is not transmitted
to the input shaft 14 of the compressor 10, so that the compressor 10 is stopped.
[0019] The compressor lock, and the electromagnetic clutch 20 on condition that the compressor
is locked will be described.
The compressor lock means a state that the scroll compression mechanism 13 of the
compression 10 is immovable, due to the liquid compression, rising of oil, or incorporation
of foreign material. When the driving power of the belt 5 is transmitted to the compressor
pulley 11 and the starting torque is beyond the given torque (the slippage generating
torque), the belt 5 slides to the compressor pulley 11.
[0020] In the present embodiment, the slippage generating torque of the electromagnetic
clutch 20 is set up to be the starting torque of the engine 2 (the starter) or higher.
In other words, during the staring on the compression locked condition, the slippage
is not generated in the electromagnetic clutch 20 and the engine 2 and the compressor
10 can not be rotated even when the electromagnetic clutch 20 is engaged, so that
the engine 2 can not be started and the operation is locked.
[0021] An avoidance control for the operation of the engine driven heat pump having the
compressor on the locked condition according to the present invention will be described
in detail, with reference to Fig. 3.
The ECU 7 starts the engine 2 (S, Step 110) by receiving ON command for starting the
engine drive heat pump 1, or ON command for starting a thermostat when beyond the
preset temperature after operating the heat pump (S, Step 100).
The ECU 7 turns s o n two electromagnetic clutches of the electromagnetic clutches
20a, 20b regardless of size of the air-conditioning load. The ECU 7 stops the driving
of the starter 6 by outputting an abnormal code E0, when the starter 6 is driven and
the rotation speed of the input shaft 14 does not reach the preset rotation speed.
When the engine 2 is not continuously stopped at three times or more due to the Eo
(S, Step 130) at the preset time t1, i.e., when the engine 2 is normally started,
each one of the electromagnetic clutches 20a or 20b is turned off (S, Step 140), the
operation for capacity control of the compression 10 is started (S, Step 150).
In this regard, Eo is an abnormal code when at least one compressor 10 is locked,
or when the starter 6 cannot be started due to malfunction or the like.
[0022] Meanwhile, the ECU 7 evaluates that at least one compressor 10 is locked (or the
starter is abnormal), when the engine 2 is continuously stopped at three times or
more due to the Eo (S, Step 130) at the preset time t1. At this time, the ECU 7 evaluates
that the operation gets stacked up and entirely stops the engine drive heat pump 1
(S, Step 210). The ECU 7 issues a warning by a warning device, so as to inform the
operator of the abnormality. In this regard, the starting clog means a state that
the rotating speed of the engine or the compressor does not reach the predetermined
rotating speed at the preset time t1, after starting the starting command by the ECU
7.
[0023] Explanation will be given on each sequence of the engine 2 and the compressors 10a,
10b with respect to the avoidance control for the operation of the engine drive heat
pump having the compressor on the locked condition., with reference to Figs. 4 and
5.
Figs. 4 and 5 shows time series as the axis of abscissas, and shows the ON/OFF operation
of the first compressor (Comp1), the ON/OFF operation of the second compressor (Comp2),
and the engine rotation speed (Nrpm) of the engine (Engine) as axis of ordinate.
[0024] Each of the sequences by the compressor lock detection control when the second compressor
10b is locked (Rock) will be described in detail, with reference to Fig. 4.
As shown in Fig. 4, after the engine 2 receive s the starting command for the engine
driven heat pump 1, the engine 2 (the starter) cannot start and stops by the Eo, because
the second compressor 10b is locked. Since the stop/restart by the E0 is continuously
performed at three times during the preset time t1, the engine driven heat pump 1
is totally stopped.
[0025] Thus, at the time of starting the air conditioning, it can be assuredly avoided that
the engine driven heat pump 1 is driven with the compressor 10b on the locked condition.
Specifically, due to the construction that the driving forces are transmitted to all
of the compressors 10a, 10b at the starting, the driving force is also transmitted
to the compressor 10b on the locked condition so as to generate the starting clog,
thereby stopping the engine driven heat pump 1. Consequently, it can be prevented
that the engine driven heat pump 1 is driven by the compressor 10a, with the compressor
10b on the locked condition. In other words, in the engine driven heat pump 1 equipped
with two compressors 10a, 10b, the starting of the air conditioning operation can
be avoided, if even one compressor is on the locked condition.
[0026] Each of the sequences by the compressor lock detection control when both of the first
compressor 10a and the second compressor 10b are normal (Normal) will be described
in detail, with reference to Fig. 5. As shown in Fig. 5, at this time, after the engine
2 receives the starting command for the engine driven heat pump 1, the engine 2 (the
starter 6) is normally started, as both of the first compressor 10a and the second
compressor 10b are normal. After that, since one electromagnetic clutch 20b is disengaged,
the engine driven heat pump 1 is driven only by the first compressor 10a. The engine
driven heat pump 1 starts the second compressor 10b, corresponding to size of the
air-conditioning load, and can be driven by two compressors.
[0027] Thus, the operation can be started from one of the compressor 10a (10b), by disengaging
the electromagnetic clutch 20b (20a) after the starting of the engine 2 has finished.
Briefly, the capacity control for the compressor corresponding to the air conditioning
load can be performed.
[Industrial applicability]
[0028] The present invention is applicable in the engine driven heat pump.