U.S. patent application number 11/648977 was filed with the patent office on 2007-07-12 for operating apparatus for a working industrial vehicle.
This patent application is currently assigned to KABUSHIKI KAISHA TOYOTA JIDOSHOKKI. Invention is credited to Hisashi Ichijo, Norihiko Kato.
Application Number | 20070161456 11/648977 |
Document ID | / |
Family ID | 38233385 |
Filed Date | 2007-07-12 |
United States Patent
Application |
20070161456 |
Kind Code |
A1 |
Kato; Norihiko ; et
al. |
July 12, 2007 |
Operating apparatus for a working industrial vehicle
Abstract
A two-way clutch is provided between an engine and a generator
motor. Further, a battery and a cargo handling pump are provided.
The generator motor is set to either a generator mode or an
electric motor mode. When a cargo handling load (detected by a
sensor) is small, the two-way clutch is set to a first state in
which transmission of driving force from the engine to the
generator motor is allowed and in which transmission of driving
force in reverse is prevented. Further, when the engine is stopped
or idled, the cargo handling pump is driven by the generator motor
in the electric motor mode. When, during the above operation, the
load increases to a level above a predetermined value, an increase
in output of the generator motor and an increase in engine RPM are
started, and when the engine RPM becomes equal to the RPM of the
generator motor, which previously increased, the two-way clutch in
the first state is connected, and the cargo handling pump is driven
by the engine.
Inventors: |
Kato; Norihiko; (Aichi-Ken,
JP) ; Ichijo; Hisashi; (Aichi-Ken, JP) |
Correspondence
Address: |
KNOBLE, YOSHIDA & DUNLEAVY
EIGHT PENN CENTER, SUITE 1350, 1628 JOHN F KENNEDY BLVD
PHILADELPHIA
PA
19103
US
|
Assignee: |
KABUSHIKI KAISHA TOYOTA
JIDOSHOKKI
AICHI-KEN
JP
|
Family ID: |
38233385 |
Appl. No.: |
11/648977 |
Filed: |
January 3, 2007 |
Current U.S.
Class: |
477/3 |
Current CPC
Class: |
Y02P 90/60 20151101;
B60W 10/08 20130101; Y02T 10/62 20130101; B60W 10/30 20130101; Y02T
10/7072 20130101; Y10T 477/23 20150115; B60L 1/003 20130101; B60L
50/61 20190201; B60W 10/02 20130101; Y02T 10/70 20130101; B60K 6/46
20130101; B60W 10/06 20130101; B60K 17/02 20130101; B60W 20/00
20130101; B60W 20/15 20160101; B60Y 2200/15 20130101; Y10S 903/946
20130101; B60K 1/02 20130101; B60W 2510/0208 20130101; B60L 2200/42
20130101; B60L 2270/145 20130101; B60W 2300/121 20130101 |
Class at
Publication: |
477/3 |
International
Class: |
B60K 1/02 20060101
B60K001/02 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 12, 2006 |
JP |
2006-004297 |
Nov 17, 2006 |
JP |
2006-311777 |
Claims
1. An operating apparatus for a working industrial vehicle,
comprising: an engine; a generator motor; a two-way clutch provided
between the engine and the generator motor; an electricity storage
means; a load driven by at least one of the engine and the
generator motor; a working load detecting means for detecting the
magnitude of a resistance load during operation of the load; and a
control means electrically connected to the engine, the generator
motor, the two-way clutch, the electricity storage means, and the
working load detecting means, wherein the control means switches
the generator motor between a generator mode in which driving force
of the engine is transmitted to the generator motor through the
two-way clutch to generate power to be stored in the electricity
storage means, and an electric motor mode in which the generator
motor is supplied with driving power from the electricity storage
means to function as an electric motor, wherein the two-way clutch
can be switched between a first state in which transmission of
driving force from the engine to the generator motor is allowed and
in which transmission of driving force from the generator motor to
the engine is prevented, and a second state in which the
transmission of the driving force from the generator motor to the
engine is allowed and in which the transmission of the driving
force from the engine to the generator motor is prevented, wherein
when the resistance load detected by the working load detecting
means is small, the control means sets the two-way clutch to the
first state, sets the engine in one of a stopped state and an
idling state, and sets the generator motor to the electric motor
mode so that the load is driven to conduct operation, wherein when,
during the operation, the working load detecting means detects an
increase in the resistance load in excess of a predetermined level,
the control means starts an increase in RPM of the engine while
increasing an output of the generator motor in the electric motor
mode, and wherein when the RPM of the engine becomes equal to the
RPM of the generator motor, the two-way clutch in the first state
is automatically connected, and the driving force of the engine is
transmitted to the load through the two-way clutch.
2. An operating apparatus for a working industrial vehicle
according to claim 1, wherein the engine can be started by setting
the two-way clutch to the second state by the control means and by
driving a crankshaft of the engine by the generator motor in the
electric motor mode.
3. An operating apparatus for a working industrial vehicle
according to claim 1, wherein when a charging amount of the
electricity storage means is larger than a predetermined charging
amount, the control means sets the two-way clutch to the second
state, and the generator motor in the electric motor mode drives a
crankshaft of the engine.
4. An operating apparatus for a working industrial vehicle
according to claim 1, wherein when the resistance load detected by
the working load detecting means is large, the control means sets
the two-way clutch to the second state, and the driving force of
the generator motor in the electric motor mode and of the engine is
transmitted to the load.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a so-called hybrid type
operating apparatus provided in a working industrial vehicle.
[0003] 2. Description of the Related Art
[0004] An example of a operating apparatus for an industrial
vehicle of this type is disclosed in JP 2005-298163 A. According to
the first embodiment of JP 2005-298163A (see FIG. 1), there is
disclosed a cargo handling apparatus for a cargo handling
industrial vehicle having an engine, a generator motor, a clutch
for connecting and disconnecting power between the engine and the
generator motor, an electricity storage means, a cargo handling
means (load to be driven), and a cargo handling load detecting
means for detecting resistance load. The generator motor is set to
either a generator mode in which a driving force of the engine is
transmitted to the generator motor through the clutch to generate
power and store the power in the electricity storage means, or an
electric motor mode in which the generator motor is supplied with
driving power from the electricity storage means to function as an
electric motor.
[0005] In the above construction, when the load detected by the
cargo handling load detecting means is small, the clutch is set to
a disconnected state to stop or idle the engine, and the cargo
handling means is driven by the generator motor in the electric
motor mode to perform cargo handling operations. When, during the
cargo handling operation, the cargo handling load detecting means
detects an increase in load in excess of a predetermined value, an
increase in engine RPM is started while increasing an output of the
generator motor in the electric motor mode. When the engine RPM
becomes equal to the RPM of the generator motor, the clutch is set
to a connected state, and the driving force of the engine is
transmitted to the cargo handling means to perform cargo handling
operations.
[0006] Further, according to the first embodiment of JP 2005-298163
A, the engine is started through cranking by the generator motor in
the electric motor mode with the clutch in the connected state.
[0007] According to the third embodiment of JP 2005-298163 A (see
FIG. 3), there is disclosed a construction in which the engine and
the generator motor are connected to each other through the
intermediation of a one-way clutch instead of the above-mentioned
clutch. With this construction, when, during cargo handling
operations, the cargo handling load detecting means detects an
increase in load in excess of a predetermined value, an increase in
the engine RPM is started while increasing the output of the
generator motor in the electric motor mode. When the engine RPM
becomes equal to the RPM of the generator motor, the one-way clutch
is automatically connected, and the driving force of the engine is
transmitted to the cargo handling means.
[0008] With this construction, there is no need to perform the
clutch connection/disconnection control (inclusive of control for
monitoring to check whether the engine RPM has become equal to the
Rpm of the generator motor) required in the first embodiment
described above, thereby achieving a simplification in electrical
construction.
[0009] However, with the construction of the third embodiment of JP
2005-298163 A, it is impossible to drive the engine by the
generator motor because the one-way clutch is then set to the
disconnected state. Thus, to start the engine, it is necessary to
provide a dedicated starter motor, which means there is some room
left for improvement (see the second and third sentences of
paragraph [0063] of JP 2005-298163 A).
SUMMARY OF THE INVENTION
[0010] The present invention has been made in view of the above
problem in the prior art. It is an object of the present invention
to make further use of a generator motor as a drive source while
maintaining the simplicity in electrical construction of the clutch
connection/disconnection control as in the third embodiment of JP
2005-298163 A.
[0011] According to the present invention, there is provided an
operating apparatus for a working industrial vehicle, including: an
engine; a generator motor; a two-way clutch provided between the
engine and the generator motor; an electricity storage means, a
load driven by at least one of the engine and the generator motor,
and a working load detecting means for detecting the magnitude of a
resistance load during operation.
[0012] The generator motor is set to either a generator mode in
which the driving force of the engine is transmitted to the
generator motor through the two-way clutch to generate power and
store the power in the electricity storage means, or an electric
motor mode in which the generator motor is supplied with driving
power from the electricity storage means to function as an electric
motor. The two-way clutch allows switching between a first state in
which the transmission of driving force from the engine to the
generator motor is allowed and in which the transmission of driving
force from the generator motor to the engine is prevented, and a
second state in which the transmission of the driving force from
the generator motor to the engine is allowed and in which the
transmission of the driving force from the engine to the generator
motor is prevented.
[0013] The "increase in resistance load to a level above a
predetermined value" includes a case in which the degree of
rapidity in the increase in resistance load is higher than a
predetermined degree of rapidity, and a case in which the
resistance load itself is not less than a predetermined value. This
applies to the following description.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] In the accompanying drawings:
[0015] FIG. 1 is a block diagram showing a forklift equipped with a
cargo handling apparatus according to an embodiment of the present
invention;
[0016] FIG. 2A is a partial sectional view showing a two-way clutch
in a first state;
[0017] FIG. 2B is a partial sectional view showing the two-way
clutch in a second state; and
[0018] FIG. 3 is a block diagram showing a forklift according to a
modification.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0019] Next, an embodiment of the present invention will be
described. FIG. 1 is a block diagram showing a forklift equipped
with a cargo handling apparatus according to an embodiment of the
present invention, FIG. 2A is a partial sectional view showing a
two-way clutch in a first state, and FIG. 2B is a partial sectional
view showing a the two-way clutch in a second state.
[0020] FIG. 1 shows the general construction of a cargo handling
apparatus (working device) 201 of a forklift 101 as a working
industrial vehicle. The cargo handling apparatus 201 is mainly
composed of an engine 111, a generator motor 113, a battery
(electricity storage means) 115, a cargo handling pump 117, a cargo
handling valve 119, a fork 118, a traveling motor 121, a traveling
unit 123, an inverter assembly 131, and an ECU (control means) 135.
The cargo handling pump 117, the fork 118, and the cargo handling
valve 119 form a cargo handling means (working means). In this
embodiment, the cargo handling pump 117 corresponds to a load
driven by the engine 111 and the generator motor 113.
[0021] The driving of the engine 111 is controlled based on a
rotation control signal imparted to a throttle actuator 151 from
the ECU 135 described below. A crankshaft (not shown) of the engine
is coaxially connected with a drive shaft (not shown) of the
generator motor 113 through the intermediation of a two-way clutch
112 for connection/disconnection of power.
[0022] The generator motor 113 can be switched as appropriate
between a generator mode in which the generator motor 113 is driven
by the engine 111 to generate power and store the power in the
battery 115, and an electric motor mode in which the generator
motor 113 is supplied with driving power from the battery 115 to
function as an electric motor. The switching control is effected
based on a control command supplied from the ECU 135 through the
inverter assembly 131.
[0023] The forklift 101 is equipped with sensors, etc., which
include a shift position sensor 141, an accelerator switch 142, an
accelerator position sensor 143, a cargo handling lever switch 144,
a cargo handling lever position sensor (cargo handling load
detecting means) 145, and an ignition switch 146. Each of these
sensors, etc. is electrically connected to the ECU 135.
[0024] When the generator motor 113 is in the generator mode, the
engine 111 serves as the drive source for the generator motor 113
and the cargo handling pump 117 arranged coaxially therewith. On
the other hand, when the generator motor 113 is in the electric
motor mode, both the engine 111 and the generator motor 113, or the
generator motor 113 alone serves as the drive source for the cargo
handling pump 117.
[0025] FIG. 2A is a schematic partial sectional view of a
construction example of the two-way clutch 112, which is equipped
with a cam shaft 51 fixed to the crankshaft of the engine 111, an
annular outer ring 52 arranged in the outer periphery of the cam
shaft 51 and fixed to the drive shaft of the generator motor 113, a
plurality of rollers 53 arranged circumferentially between the cam
shaft 51 and the outer ring 52, and a retainer 54 supporting the
rollers 53. The two-way clutch 112 is further equipped with an
electromagnet (not shown). By switching between energization and
non-energization of the electromagnet, the phase of the retainer 54
with respect to the cam shaft 51 is changed, whereby it is possible
to change the positions of the rollers 53 in what may be termed
wedge-shaped spaces 56 described below.
[0026] The outer peripheral surface of the cam shaft 51 is
partially cut into flat surfaces to form cam surfaces 55. The
portions corresponding to the cam surfaces 55 form the wedge-shaped
spaces 56 between the cam shaft 51 and the outer ring 52. Each
wedge-shaped space 56 is configured such that its width is maximum
at the center in the circumferential direction while its width
gradually diminishes toward both circumferential ends. In the
wedge-shaped spaces 56, there are arranged the rollers 53 supported
by the retainer 54.
[0027] The width of the central portion in the circumferential
direction of each wedge-shaped space 56 is set somewhat larger than
the outer diameter of the rollers 53, so when the rollers 53 are
respectively situated at the circumferential centers of the
wedge-shaped spaces 56, the cam shaft 51 and the outer ring 52 slip
with respect to each other. When the retainer 54 is displaced to
move each roller 53 to either end of each wedge-shaped space 56, it
is possible to jam the rollers 53 in the wedge-shaped spaces 56. In
this state, it is possible to transmit to the outer ring 52 the
rotation of the cam shaft 51 in the direction in which the jamming
is intensified (or to transmit to the cam shaft 51 the rotation of
the outer ring 52 in the direction in which the jamming is
intensified).
[0028] While FIG. 2A and 2B only shows the cam surface 55, the
wedge-shaped space 56, and one roller 53, a plurality of similar
structures are circumferentially arranged around the cam shaft 51,
thereby forming the two-way clutch 112.
[0029] In the above-described two-way clutch 112, in the state
shown, for example, in FIG. 2A, the rollers 53 are moved to the
left through the intermediation of the retainer 54 to be jammed
between the cam shaft 51 and the outer ring 52. When, in this
state, the engine 111 is driven to rotate the cam shaft 51 in the
direction of an arrow A, the rollers 53 make a relative movement to
the left-hand side in FIG. 2A, that is, in the direction in which
the wedge-engagement, in which they are jammed between the cam
shaft 51 and the outer ring 52, is further intensified. Thus, the
above-mentioned rotation of the cam shaft 51 is transmitted to the
outer ring 52 through the rollers 53, thereby making it possible to
drive the drive shaft of the generator motor 113 fixed to the outer
ring 52 in the direction of an arrow B.
[0030] When, in the state of FIG. 2A, the generator motor 113 is
driven to rotate the outer ring 52 in the direction of the arrow B,
the rollers 53 are dragged by the outer ring 52 to move to the
right (to the respective circumferential centers of the
wedge-shaped spaces 56), so the engagement between the cam shaft 51
and the outer ring 52 through the intermediation of the rollers 53
is canceled. Thus, the outer ring 52 slips relative to the cam
shaft 51, and it is impossible to drive the cam shaft 51 (that is,
crankshaft of the engine 111) in the direction of the arrow A.
[0031] On the other hand, in a case where the two-way clutch 112 is
switched to the state of FIG. 2B, when the generator motor 113
drives the outer ring 52 in the direction of the arrow B relative
to the engine 111 in a non-driving state or a low rotational state
such as an idling state (when the engine 111 is in the low
rotational state such as the idling state, the generator motor 113
drives the outer ring 52 at an RPM substantially higher than the
RPM of the engine 111), the rollers 53 make a relative movement to
the left in FIG. 2B to respectively move to the circumferential
centers of the wedge-shaped spaces 56, so the engagement between
the cam shaft 51 and the outer ring 52 through the intermediation
of the rollers 53 is canceled. In this state, the outer ring 52
slips relative to the cam shaft 51. Thus, the outer ring 52 (that
is, the drive shaft of the generator motor 113) can rotate in the
direction of the arrow B without receiving the load of the engine
in the non-driving state.
[0032] On the other hand, when the generator motor 113 further
drives the outer ring 52 in the direction of the arrow B relative
to the engine 111 in the non-driving state or the low rotational
state such as the idling state, the rollers 53 are dragged by the
outer ring 52 to move to the right in FIG. 2B to be jammed between
the cam shaft 51 and the outer ring 52, so the above-mentioned
rotation of the outer ring 52 is transmitted to the cam shaft 51,
making it possible to generate a force for driving the cam shaft 51
(that is, the crankshaft of the engine 111) in the same direction
as that of the arrow B.
[0033] As described above, in this embodiment, the two-way clutch
112 can be switched between the state of FIG. 2A, in which the
transmission of driving force from the engine 111 to the generator
motor 113 is allowed and in which the transmission of driving force
from the generator motor 113 to the engine 111 is prevented, and
the state of FIG. 2B, in which the transmission of the driving
force from the generator motor 113 to the engine 111 is allowed and
in which the transmission of the driving force from the engine 111
to the generator motor 113 is prevented.
[0034] In other words, in the state of FIG. 2A, when the RPM of the
engine 111 is higher than the RPM of the generator motor 113, the
two-way clutch 112 is in the connected state and transmits the
driving force, whereas, when the RPM of the generator motor 113 is
higher than the RPM of the engine 111, the two-way clutch 112 is in
the disconnected state and transmits no driving force. Similarly,
in the state of FIG. 2B, when the RPM of the generator motor 113 is
higher than the RPM of the engine 111, the two-way clutch 112 is in
the connected state and transmits driving force acting in the same
direction as that of the arrow B. In the following, the state of
FIG. 2A will be referred to as "first state", and the state of FIG.
2B will be referred to as "second state". The switching between the
first state and the second state is effected through switching
between energization and non-energization of the above-mentioned
electromagnet based on a switching signal from the ECU 135.
[0035] The battery 115 stores the electricity generated by the
generator motor 113 in the generator mode (and the traveling motor
121), and supplies, as needed, driving power for the traveling
operation and cargo handling operation of the forklift 101 as
appropriate. The storage and discharge of electricity in and from
the battery 115 is controlled through the inverter assembly 131
connected to the ECU 135.
[0036] The traveling operation of the forklift 101 is effected
through the traveling motor 121 and the traveling unit 123 driven
by the traveling motor 121. The traveling motor 121 is driven by
driving power supplied from the battery 115 through the inverter
assembly 131. The cargo handling operation of the forklift 101 is
effected through the cargo handling pump 117, the fork 118, and the
cargo handling valve 119 for distributing, as appropriate, working
fluid from the cargo handling pump 117 to the fork 118 side (more
specifically, to a mast raising/lowering cylinder).
[0037] The ECU 135 performs system control on the forklift 101 as a
whole, and the system control includes storage/discharge control
for the battery 115. Input as appropriate to the ECU 135 are shift
position information detected by the shift position sensor 141,
accelerator ON/OFF information detected by the accelerator switch
142, accelerator opening information detected by the accelerator
position sensor 143, cargo handling lever ON/OFF information
detected by the cargo handling lever switch 144, cargo handling
lever opening information detected by the cargo handling lever
position sensor 145, ON/OFF information detected by the ignition
switch 146, information on the engine 111 such as RPM (which can be
detected by an RPM detecting sensor 152) and temperature,
voltage/temperature information on the battery 115, information on
the generator motor 113 such as RPM (which can be detected by an
RPM detecting sensor 153), output, temperature, etc.
[0038] Based on the input information as mentioned above, a control
signal for the engine 111 is output from the ECU 135 to the
throttle actuator 151. Further, various control signals, such as a
mode switching signal for the generator motor 113, an electricity
storage control signal for the battery 115, and a control signal
for the traveling motor 121, are output from the ECU 135 to the
inverter assembly 131 to perform system control on the forklift
101. Further, the ECU 135 outputs a switching signal to the two-way
clutch 112 to perform control for switching the two-way clutch 112
between the first state and the second state.
[0039] Next, the operation of the operating apparatus of this
embodiment will be described. In particular, when no high output is
needed for the cargo handling operation, the two-way clutch 112 is
set to a state (that is, the first state shown in FIG. 2A) in which
it is possible to drive the generator motor 113 from the engine 111
side but in which it is impossible to drive the engine 111 from the
generator 113 side. The generator motor 113 is set to the generator
mode.
[0040] In this state, the engine 111 serves as a drive source for
both the generator motor 113 in the generator mode and the cargo
handling pump 117. In the following, this state will be referred to
as a "first mode". In this embodiment, the judgment as to whether
high output is needed for the cargo handling operation or not is
made by the ECU 135, which checks as appropriate whether there is a
high demand for cargo handling drive or not based on information
from the cargo handling lever position sensor 145.
[0041] In the first mode, the driving force of the engine 111 is
transmitted to the generator motor 113 in the generator mode, and
the electricity generated by the generator motor 113 is
successively stored in the battery 115. The cargo handling pump 117
is constantly driven as the crankshaft of the engine 111 rotates,
supplying working fluid (pressure oil in this embodiment) to the
cargo handling valve 119. When no cargo handling operation is to be
conducted, the working fluid passes through the cargo handling
valve 119 to be fed back to a tank (not shown).
[0042] In the first mode, when the cargo handling load (resistance
load) is small, the ECU 135 performs control, for example, to
increase the amount of generated electricity to be stored in the
battery 115, effecting control such that the load on the engine 111
is of a magnitude suitable for operating the engine 111 under a
predetermined optimum condition. The optimum condition is a
condition (in terms of RPM, fuel injection amount, etc.) allowing
operation of the engine at optimum fuel efficiency, and is
previously determined by experiment or the like. In a case, for
example, in which the cargo handling load is small with the battery
115 almost fully charged, control may be conducted by the ECU 135
so as to prevent power generation by the generator motor 113.
[0043] When the forklift 101 is to be moved, the ECU 135 causes the
battery 115 to discharge through the inverter assembly 131,
supplying driving power to the traveling motor 121. By driving the
traveling motor 121, the traveling unit 123 connected to the
traveling motor 121 performs the moving operation.
[0044] When high output is needed for the cargo handling operation,
that is, when it is judged by the ECU 135 that there is a high
demand for cargo handling drive based on information from the cargo
handling lever position sensor 145, the ECU 135 transmits a control
signal to switch the generator motor 113 to the electric motor
mode. The ECU 135 outputs a switching signal to switch the two-way
clutch 112 to the state in which it is possible to drive the engine
111 from the generator motor 113 side but in which it is impossible
to drive the generator motor 113 from the engine 111 side (that is,
the second state shown in FIG. 2B). In the following, this state
will be referred to as a "second mode".
[0045] In the second mode, the cargo handling pump 117 is driven by
both the engine 111 and the generator motor 113 in the electric
motor mode. Thus, the driving of the cargo handling pump 117 by the
engine 111 is assisted by the generator motor 113 in the electric
motor mode, thereby making it possible to execute a high-output
cargo handling operation to a sufficient degree even if the engine
111 is of a low output type.
[0046] When the cargo handling drive demand is relatively low, and
it is determined by the ECU 135 that there is no need for such an
output as would require cooperation of the engine 111 and the
generator motor 113 in the electric motor mode, the ECU 135 outputs
a control signal to set the generator motor 113 to the electric
motor mode. The two-way clutch 112 is set to the first state
mentioned above. In this case, while the generator motor 113 in the
electric motor mode drives the cargo handling pump 117, the engine
111 does not contribute to the driving of the cargo handling pump
117. In the following, this state will be referred to as a "third
mode".
[0047] In the third mode, the engine 111 is idled or stopped,
thereby improving the energy efficiency at the time of driving the
cargo handling pump 117. Further, since the two-way clutch 112 is
in the first state, there is no fear of a large load (engine
braking) being applied from the engine 111 side when the generator
motor 113 drives the cargo handling pump 117.
[0048] During the cargo handling operation in the third mode, there
may arise a case in which the cargo handling load increases as a
result, for example, of an increase in the opening of the cargo
handling lever position sensor 145. Upon detection of the increase
in the cargo handling load, the ECU 135 examines the degree of
increase (rapidity) in the cargo handling load. For example, when
the cargo handling lever is tilted by an angle larger than a
predetermined angle within a predetermined period of time, it is
determined that the degree of increase (rapidity) in the cargo
handling load is large.
[0049] When it is determined by the ECU 135 that the degree of
increase in the cargo handling load is below a predetermined value,
the ECU 135 transmits a control signal to the inverter assembly 131
to simply increase the output of the generator motor 113 in the
electric motor mode, thereby keeping up with the increase in the
cargo handling load. At this time, the engine 111 maintains the
idling state or the stopped state, thereby achieving an improvement
in energy efficiency.
[0050] On the other hand, when the degree of increase in the cargo
handling load is not less than the predetermined value, control is
effected such that the output of the generator motor 113 in the
electric motor mode is increased and that the increase in the RPM
of the engine 111is started immediately (If the engine 111 is
stopped, the engine 111 is started at once, and an increase in the
RPM of the engine is started). As compared with the engine 111, the
generator motor 113 allows quicker transition to a high output
state, so the delay in the cargo handling operation can be
minimized or substantially reduced to zero.
[0051] At the stage where the RPM of the engine 111 has gradually
increased to become equal to the RPM of the generator motor 113,
the two-way clutch 112, which has been in the first state, is
automatically connected, and the driving force of the engine 111 is
transmitted to the cargo handling pump 117.
[0052] As described above, when the cargo handling load is
relatively small, the cargo handling apparatus is set to the third
mode to idle or stop the engine 111 to thereby achieve an
improvement in energy efficiency (fuel efficiency). When, in the
third mode, the cargo handling load (rapidly) increases beyond the
predetermined value, switching is effected to the driving of the
cargo handling pump 117 by the engine 111, whereby it is possible
to conduct the cargo handling operation nimbly by utilizing the
large output provided by the engine 111. To set the engine 111,
which has been idling or stopped, to a high output state to effect
transition to the driving by the engine 111, generation of some
time lag is inevitable. This, however, can be coped with by quickly
increasing the output of the generator motor 113, so there is no
fear of a delay in the cargo handling operation due to a reduction
in operational responsiveness, nor is there any reduction in
operational efficiency involved in the cargo handling
operation.
[0053] Further, when the RPM of the engine 111 becomes equal to the
RPM of the generator motor 113, the two-way clutch 112 in the first
state is automatically connected, so it is possible to avoid a
temporary reduction in the input RPM of the cargo handling pump 117
at the time of transition to the driving by the engine 111. Thus,
during the operation of lifting a cargo, there is no fear of the
speed at which the fork 118 is raised being reduced temporarily to
cause an unpleasant vibration in the machine or a delay in the
cargo handling operation.
[0054] Further, as compared with the construction (construction of
the first embodiment of JP 2005-298163 A) in which the engine RPM
and the RPM of the generator motor 113 are monitored on the ECU 135
side and in which the electromagnetic clutch is connected when the
engine RPM becomes equal to the RPM of the generator motor 113, it
is possible to reduce the load on the ECU 135, and to simplify the
electrical construction thereof. Further, since there is no need to
perform electrical control, it is possible to reduce the frequency
of failure, thereby reducing the frequency of maintenance.
[0055] Next, control at the time of engine start will be described.
When the ignition switch 146 is turned ON while the engine 111 is
stopped, the ECU 135 immediately transmits a switching signal to
the two-way clutch 112 to effect switching to the state (second
state of FIG. 2B) in which transmission of driving force from the
generator motor 113 to the engine 111 is allowed and in which
transmission of driving force from the engine 111 to the generator
motor 113 is prevented. Then, the generator motor 113 is set to the
generator mode, and the crankshaft (not shown) of the engine 111 is
driven through the two-way clutch 112 (cranking). This causes the
engine 111 to be started, and after that, the forklift 101 performs
traveling operation, cargo handling operation, etc. according to
the manipulation performed.
[0056] Due to the above-described construction, it is possible to
omit a special starter motor for starting the engine 111, so it is
possible to reduce the number of components and the production
costs. Further, since it is a general practice for the generator
motor 113 in the electric motor mode to be designed so as to have a
larger torque than a starter motor, it is possible to reduce the
vibration at the time of cranking.
[0057] Next, a regenerative brake in the traveling motor 121 will
be described. In this embodiment, like the generator motor 113, the
traveling motor 121 is set to either a generator mode or an
electric motor mode. In the generator mode, the traveling motor 121
is supplied with driving power from the battery 115 and serves as
an electric motor, thereby driving the traveling unit 123 as
described above to cause the forklift 101 to travel. On the other
hand, at the time, for example, of braking the forklift 101, the
traveling unit 123 is set to the generator mode. The traveling
motor 121 is driven from the traveling unit 123 side to generate
power, and the power generated is stored in the battery 115.
[0058] Here, suppose a large amount of power is supplied to the
battery 115 from the traveling motor 121 in the generator mode as
in a case in which the forklift 101 is going down a long downward
slope, and the battery 115 is almost fully charged. If, in this
state, the power from the traveling motor 121 is continuously
supplied, the battery 115 is overcharged, resulting in a marked
reduction in the service life of the battery 115.
[0059] In view of this, in this embodiment, the ECU 135 detects and
monitors the charging amount of the battery 115 by an appropriate
method, such as voltage detection. When it is determined that the
charging amount of the battery 115 is in excess of a predetermined
charging amount (for example, a predetermined value corresponding
to approximately 80% to 90% of the full charging amount), the ECU
135 switches the two-way clutch 112 to the second state, and stops
(or idles) the engine 111. Further, the generator motor 113 is
driven in the electric motor mode to drive the crankshaft of the
engine 111. As a result, the generator motor 113 is driven while
braking the engine, so any surplus energy that cannot be stored in
the battery 115 can be efficiently consumed (discharged) by the
generator motor 113, thereby making it possible to rationally avoid
overcharging of the battery 115.
[0060] As described above, the cargo handling apparatus 201 of the
forklift 101 of this embodiment is equipped with the engine 111,
the generator motor 113, the two-way clutch 112 provided between
the engine 111 and the generator motor 113, the battery 115, the
cargo handling pump 117 for driving the fork 118, and the cargo
handling lever position sensor 145. The generator motor 113 is set
to either the generator mode, in which the driving force of the
engine 111 is transmitted to the generator motor 113 through the
two-way clutch 112 to generate power to charge the battery 115
with, or the electric motor mode, in which the generator motor 113
is supplied with driving power from the battery 115 to function as
an electric motor. The two-way clutch 112 can be switched between
the first state (FIG. 2A), in which transmission of driving force
from the engine 111 to the generator motor 113 is allowed and in
which transmission of driving force from the generator motor 113 to
the engine 111 is prevented, and the second state (FIG. 2B), in
which transmission of driving force from the generator motor 113 to
the engine 111 is allowed and in which transmission of driving
force from the engine 111 to the generator motor 113 is prevented.
When the cargo handling load detected by the cargo handling lever
position sensor 145 is small, the cargo handling apparatus is set
to the above-mentioned third mode, the two-way clutch 112 is set to
the first state, and the engine 111 is stopped or idled. Further,
the cargo handling pump 117 is driven by the generator motor 113 in
the electric motor mode to perform cargo handling operations. When,
during the operation in the third mode, the cargo handling lever
position sensor 145 detects an increase in cargo handling load
beyond a predetermined level, an increase in the RPM of the engine
111 is started while increasing the output of the generator motor
113. When the engine RPM becomes equal to the RPM of the generator
motor 113, the two-way clutch 112 in the first state is
automatically connected, and the driving force of the engine 111 is
transmitted to the cargo handling pump 117 through the two-way
clutch 112 to perform cargo handling operation using the fork
118.
[0061] Thus, when the cargo handling load is small, the two-way
clutch 112 is set to the first state to drive the cargo handling
pump 117 by the generator motor 113 in the electric motor mode, and
the engine 111 is stopped or idled, thereby achieving an
improvement in terms of energy efficiency. When an increase in
cargo handling load is detected by the cargo handling lever
position sensor 145, control is first effected to increase the
output of the generator motor 113 to thereby secure responsiveness.
When it is in the first state, the two-way clutch 112 transmits
torque from the engine 111 to the generator motor 113, and cuts off
torque transmission in the reverse direction, so it is possible to
reliably prevent a load (engine braking, etc.) from the engine 111
side from being applied to the generator motor 113. When the engine
RPM becomes equal to the RPM of the generator motor 113, the
two-way clutch 112 in the first state is automatically connected,
so there is no need to perform a special clutch
connection/disconnection control, thereby making it possible to
simplify the electrical construction of the ECU 135.
[0062] Further, by setting the two-way clutch to the second state
as appropriate, it is also possible to drive the engine 111 side by
the generator motor 113 in the electric motor mode.
[0063] Further, in this embodiment, when the ignition switch 146 is
turned ON, the crankshaft of the engine 111 is driven by the
generator motor 113 in the electric motor mode while setting the
two-way clutch 112 to the second state (FIG. 2B), thereby starting
the engine.
[0064] Thus, it is possible to effect cranking of the engine 111 by
the generator motor 113 in the electric motor mode, so it is
possible to omit a dedicated starter motor for starting the engine
111, thereby simplifying the construction of the cargo handling
apparatus 201. Further, due to the large torque of the generator
motor 113 in the electric motor mode, it is possible to reduce
vibration at the time of cranking.
[0065] Further, in this embodiment, when the charging amount of the
battery 115 is in excess of a predetermined charging amount, the
two-way clutch 112 is set to the second state (FIG. 2B), and the
crankshaft of the engine 111 is driven by the generator motor 113
in the electric motor mode.
[0066] Thus, by driving the generator motor 113 in the electric
motor mode during engine braking, it is possible to efficiently
discharge the energy of the battery 115, thereby making it possible
to prevent the battery 115 from being overcharged.
[0067] Further, in this embodiment, when the cargo handling load
detected by the cargo handling lever position sensor 145 is large,
the cargo handling apparatus is set to the second mode, and the
two-way clutch 112 is set to the second state (FIG. 2B) to perform
operation by transmitting the driving force of the generator motor
113 in the electric motor mode and of the engine 111 to the cargo
handling pump 117.
[0068] Thus, the driving of the cargo handling pump 117 by the
engine 111 is assisted by the generator motor 113 in the electric
motor mode, so, even when, for example, the engine 111 is of a low
output type, it is possible to conduct high output operation to a
sufficient degree.
[0069] Apart from the plurality of embodiments and modifications of
the present invention described above, the present invention
further allows the following modification.
[0070] As in a cargo handling apparatus 202 for a forklift 102
shown in FIG. 3, it is possible to arrange a CVT (Continuously
Velocity Transmission) 114 between the two-way clutch 112 and the
generator motor 113. In this case, when the cargo handling load
rapidly increases in the third mode, the transmission ratio of the
CVT 114 is set to an appropriate level, whereby the engine RPM
after the change of transmission ratio by the CVT 114 becomes equal
to the RPM of the generator motor 113 at an early stage to cause
the two-way clutch 112 in the first stage to be automatically
connected, thereby making it possible to transmit the driving force
of the engine 111 to the cargo handling pump 117. Thus, even if the
cargo handling load increases, it is possible to assist the
generator motor 113 by the engine 111 at an early stage, thereby
making it possible to prevent the generator motor 113 from being
overcharged.
[0071] In the construction of FIG. 3, it is also possible to adopt
an arrangement in which, even after the engine RPM after the change
of transmission ratio by the CVT 114 has become equal to the RPM of
the generator motor 113 and the two-way clutch 112 in the first
state has been automatically connected, control is effected to
change the transmission gear ratio of the CVT 114 in response to an
increase in engine RPM. Due to this arrangement, even while the RPM
of the engine 111 increases from a low level until it becomes equal
to the RPM of the generator motor 113, it is possible to transmit
the driving force of the engine 111 to the cargo handling pump 117.
Further, it is also possible for the CVT 114 to be arranged between
the two-way clutch 112 and the engine 111.
[0072] The apparatus layout for the generator motor 113, the engine
111, etc. is not restricted to the one shown. For example, instead
of being arranged coaxially with the engine 111, the generator
motor 113 may also be arranged at a side of the engine 111.
[0073] While in this embodiment the cargo handling lever position
sensor 145 serves as the cargo handling load detecting means, it is
also possible to adopt some other arrangement. For example, it is
possible to adopt an arrangement in which the pressure of the
pressure oil discharged from the cargo handling pump 117 is
detected by a pressure sensor, thereby judging the cargo handling
load (resistance load) to be high when the pressure detected is
high. Further, it is also possible to provide a load sensor at an
appropriate position on the fork 118 to detect the weight of a
cargo when lifting the cargo by the fork 118, thereby judging the
cargo handling load to be high when the weight of the cargo
detected is large. Of course, it is also possible to adopt a
construction in which the detection values of the cargo handling
lever position sensor 145 and the pressure sensor, the load sensor,
etc. are combined with each other to comprehensively judge the
magnitude of the cargo handling load.
[0074] In the above embodiment, the degree of rapidity in an
increase in cargo handling load detected by the cargo handling load
detecting means is calculated to control an increase in the output
of the generator motor 113 described above and an increase in
engine RPM. This, however, should not be construed restrictively.
It is also possible to control an increase in the output of the
generator motor 113 and an increase in engine RPM on condition that
the detected resistance load value itself is not less than a
predetermined value.
[0075] While in the above embodiment the cargo handling pump 117
supplies working fluid (pressure oil) under pressure to the cargo
handling valve 119, it is also possible to provide the forklift 101
with a hydraulic power steering device, a hydraulic brake device,
etc., thereby distributing pressure oil under pressure not only to
the cargo handling valve 119 but also to such devices as mentioned
above. In this case, the single cargo handling pump 117 can serve
as the pressure oil supply source for the power steering device,
the brake device, etc., whereby the number of components is reduced
to achieve a reduction in size, and further, a reduction in
cost.
[0076] The construction of the two-way clutch 112 can be changed
from the one described above with reference to FIGS. 2A and 2B to
some other construction. Further, it is also possible to adopt a
two-way clutch which can assume a third state in which the driving
force from the engine 111 is not transmitted to the generator motor
113 and in which the driving force of the generator motor 113 is
not transmitted to the engine 111, either.
[0077] The load to be driven by the engine 111 and the generator
motor 113 can be changed from the cargo handling pump 117 to some
other load (for example, hydraulic pump for driving a power
steering device) Further, the operating apparatus of the present
invention is not restricted to a forklift, but is applicable to
industrial vehicles in general for conducting cargo handling and
other operations.
* * * * *