Patent Application
20100147165
The present application claims priority from Japanese patent application serial No. P2007-159776, filed on Jun. 18, 2007, the content of which is hereby incorporated by reference into this application.
1. Technical Field of the Invention
The present invention relates to an industrial machine, such as a press machine, particularly a configuration for transmitting energy of a flywheel to a load part for driving.
2. Description of the Related Art
A press machine can be exemplified as an industrial machine requiring large amount of driving torque in a short time. In press machines, it has been considered to control velocity of a slider that performs a press process in order to freely perform press.
Further, technologies have been disclosed in Patent Documents, such as, JP-A-H6(1994)-190598, JP-A-H11(1999)-33797, or JP-A-2004-344946.
Technologies illustrated in
Further, a press machine that drives a slider using only driving force of a motor, as shown in
According to the technologies disclosed in JP-A-H6(1994)-190598 and JP-A-H11(1999)-33797 shown in
An object of the present invention is to provide an industrial machine, such as a press machine, in consideration of the problems in the related art, which prevents the increase in capacity or size of a driving motor or a controller of the driving motor while freely controlling the velocity of a driving load, such as a slider.
In order to overcome the problems, it is an object of the invention to provide a small-sized industrial machine having high performance.
The present invention is a technology that is capable of removing the problems and achieving the object.
That is, the present invention provides an industrial machine, such as a press machine that rotates a load driving shaft using energy stored in a flywheel, in which an output shaft of a reduction gear set is connected to the load driving shaft, an input-shaft-sided gear of the reduction gear set is driven by a first motor, a differential mechanism is connected to the flywheel, the differential mechanism is configured such that a planetary gear is connected to a carrier, the output shaft of the reduction gear set is connected to the carrier, such that rotational force inputted from a sun gear is transmitted to the flywheel and stored as energy while the stored energy is supplied to the sun gear and the carrier through the planetary gear. Further, the sun gear of the differential mechanism is driven by a second motor and the operational condition of the first and second motors is controlled by a motor control/drive circuit on the basis of information about rotational angle of the load driving shaft. Therefore, energy is stored in the flywheel by increasing rotation of the second motor according to the rotational angle position of the load drive shaft, the stored energy is outputted to the second motor and the load driving shaft, and the load driving shaft is driven by the total torque of the torque by the first motor and the torque by the energy stored in the flywheel while energy is regenerated from the second motor.
Further, the input-shaft-sided gear of the reduction gear set of which the output shaft is connected to the load driving shaft is disposed above a rotary body that is connected to first and second differential mechanisms, a planetary gear of each of the first and second differential mechanism is connected to the flywheel, and sun gears are driven by separate motors, respectively.
Embodiments are described hereafter with reference to the accompanying drawings.
Referring to
Referring to
Referring to
In a motor S velocity control unit 102, the velocity command ωCR of the crankshaft 4 is inputted, control calculation is performed by feed-backing information about velocity and location of the motor S 22, and a motor S torque command τSR is outputted to a motor S torque control unit 103. In the motor S torque control unit 103, the inverter S 202 is controlled for a motor S torque command τSR, and the velocity ωS of the motor S 22, that is, the velocity ωC of the crankshaft 4 is controlled. Accordingly, the velocity of the slider 6 which is determined by the rotational angle θC of the crankshaft 4 is controlled. Further, instead of controlling the velocity ωS of the motor S 22, current of the motor S 22 may be controlled.
In the press process, necessary torque may not be sufficiently provided only by the torque τS of the motor S 22. Therefore, required torque τR, which is the insufficient torque, is outputted from the motor velocity control unit 102 to a flywheel velocity control unit 104.
In the flywheel velocity control unit 104, a motor G torque command τGR is preferentially made by the required torque τR. However, when there is no required torque τR, in the flywheel velocity control unit 104, the flywheel velocity command ωFR is generated and the following control is performed.
That is, information about the velocity ωG of the motor G 21 and velocity ωS of the motor S 22 is inputted and the velocity ωF of the flywheel 23 is calculated by the following equation,
ωF=(kGωG−kSωS)/kF (Eq. 1)
where kG and kF are a gear ratio of the differential mechanism 24, and kS is a gear ratio of the reduction gear set 12. Further, Eq. 1 is obtained by the following.
That is, in the differential mechanism 24, the following equation is satisfied for the velocity ωC of the crankshaft 4.
ωC=kGωG−kFωF (Eq. 2)
Further, relationship between the velocity ωS of the motor S 22 and the velocity ωC of the crankshaft 4 is obtained by the following equation.
ωC=kSωS (Eq. 3)
Therefore, the velocity of ωF of the flywheel 23 is obtained from Eq. 1, by satisfying Eq. 2 and Eq. 3.
Next, the difference between the flywheel velocity command ωFR and the calculated velocity ωF of the flywheel 23 is calculated, and the motor G torque command τGR is calculated by feed-back control on the basis of the calculated result. Further, the required torque τR, which is the motor G torque command τGR as described above, is preferentially made, but it may be determined by the rotational angle θC of the crankshaft 4 whether to use the motor G torque command τGR that can be obtained by the feed-back control or the required torque τR. The motor G torque command τGR obtained as described above is outputted to the motor G torque control unit 105. In the motor G torque control unit 105, torque control calculation of the motor G 21 is performed, and the inverter G 201 is controlled by outputting a signal based on the calculated result to the inverter G 201.
Next, the operation of the press machine shown in
The acceleration section is a section where the slider 6 starts to be lifted from a bottom dead center. In the acceleration section, the velocity ωC of the crankshaft 4 is increased. Therefore, mainly the motor S 22 applies acceleration torque to the crankshaft 4.
The high-velocity section is a section where the slider is positioned near a top dead center. The crankshaft 4 rotates at a high velocity in the high-velocity section. Because acceleration torque is not needed in the high-velocity section, torque of the crankshaft 4 is small. The velocity of the crankshaft is controlled by the motor S 22 while the motor G 21 is controlled to store energy to the flywheel 23 and the velocity ωF of the flywheel 23 is increased. Further, in the acceleration section, control for accelerating the motor S 22 and gradually increasing the velocity ωF of the flywheel 23 may also be performed when the electric capacity of the commercial power source 19 is sufficient.
The deceleration section is a section where the crankshaft 4 is positioned near the bottom dead center across the top dead center. In the deceleration section, energy is further stored to the flywheel 23 by regeneration of the motor S 22.
The press section is a section where the slider 6 is positioned closer to the bottom dead center and the press process is performed at a low velocity. Therefore, the crankshaft 4 needs large torque, such that the motor S 22 is driven while the motor G 21 is decelerated. As the motor G 21 is decelerated, energy is supplied from the flywheel 23 to the motor G 21 by the principle of the differential mechanism 24, which is described below, while the energy of the flywheel 23 is also supplied to the carrier 28. Accordingly, the torque τS of the motor S 22 and the torque generated at the carrier 28 are increased in the crankshaft 4, such that large torque can be generated.
In the press machine show in
The operational principle of the press machine of
Assuming that torque of the motor G 21, the motor S 22, the flywheel 23, the carrier 28, and the crankshaft 4 is τG, τS, τF, τCA, and τC, respectively, and there is no loss in the differential mechanism 24, the following equations are obtained.
τCA=τG/kG=τF/kF (Eq. 4)
τC=τCA+τS/kS (Eq. 5)
Power PG inputted from the motor G 21 to the differential mechanism 24, power PF outputted from the differential mechanism 24 to the flywheel 23, and power PCA outputted from the carrier 28 to the crankshaft 4 are respectively PG=τGωG, PF=τFωF, and PCA=τCAωC, and
P
CA
=P
G
−P
F (Eq. 6)
At the start of the press section, the flywheel 23 rotates at a high velocity in the negative direction at a high velocity ωF. The velocity ωC of the crankshaft 4 is decreased to a predetermined small positive value. Therefore, the velocity ωG of the motor G 21 is a negative value by Eq. 2. In this condition, when the torque τG of the motor G 21 is positive, from Eq. 4, the τCA and τF become positive, and the power PF, PG become negative. Further, the power PCA becomes positive. As can be clearly seen from Eq. 5, the positive value of the τCA means the torque τC of the crankshaft 4 is larger than the torque τC/kS by the motor S 22, such that pressing force by the slider 6 is large. Further, the negative values of the Power PF, PG means that power is outputted from the flywheel 23 to the differential mechanism 24 and the power is transmitted from the differential mechanism 24 to the motor G 21. Further, since the power PCA is positive, power is outputted from the carrier 28 to the crankshaft 4. That is, a portion of the energy of the flywheel 23 is regenerated by the motor G 21 and is converted into electric energy, the crankshaft 4 is driven by the motor S 22 through the reduction gear set 12. Further, the crankshaft 4 is directly driven by the carrier 28.
Therefore, the energy stored to the flywheel 23 from the acceleration section to the deceleration section can be used for the press process in the press section, such that it is possible to reduce the power capacity of the commercial power source 19, which is determined by a desired momentary power. In particular, when the capacity of the electric storage device 29 is large, the power from the commercial power source can be equalized, and it is possible to provide a press machine that can be used at a small factory, to reduce the maximum power of a desired commercial power source. Because the force for driving the slider 6 is determined by the amount of change of the driving torque of the motor S 22 and the energy of the flywheel 23, which is controlled by the motor G 21, that is, input/output power of the flywheel 23, power for the two motors is decreased. Accordingly, it is possible to reduce the rating capacity of the two motors and the power amplifier 20. Further, it is possible to reduce the capacity of the electric storage device 29 that stores electric energy, by collaboratively controlling the two motors, and reduce the size of the electric storage device 29, in addition to the motor and power amplifier 20. Further, because the amount of needed energy depends on the type of press process, energy that is stored in the flywheel 23 or the electric storage device 29 may reach a rating value or a predetermined level between the acceleration section and the deceleration section. In this case, energy is not stored from the above section to the press section and only sliding is performed with the stored energy kept.
According to the first embodiment, by collaboratively controlling plural motors, it is possible to drive the slider 6 to have high performance and various functions, using the power from the commercial power source and the energy stored in the flywheel 23, and achieve a small-sized press machine having high performance.
Further, in the embodiment shown in
In general, in the differential mechanism, the sun gear has a smaller diameter than the ring gear, such that the number of teeth is small and the number of revolutions is large. Therefore, as shown in
According to the second embodiment, by collaboratively controlling plural motors, it is possible to drive the slider to have high performance and various functions, using power from the commercial power source and the energy stored in the flywheel, and achieve a small-sized press machine having high performance.
Connection of a motor A 39 that is a first motor, a motor B 40 that is a second motor, a flywheel 41, and a differential mechanism is described hereafter. One differential mechanism that is a first differential mechanism includes a sun gear 43 connected to the motor A 39, a planetary gear 44, and a ring gear 45, and the other differential mechanism that is a second differential mechanism includes a sun gear 46 connected to the motor B 40, a planetary gear 47, and a ring gear 48. Both of the ring gears 45, 48 are integrally rotated with a rotary body 42. As the ring gears 45, 48 rotate, a slider 6 is reciprocated up/down by a reduction gear set 12. Further, the flywheel 41 is also a carrier of the planetary gears 44, 47. That is, the flywheel 41 functions as a carrier of the differential mechanism, in addition to storing energy.
Assuming that the velocities of the motor A 39, the motor B 40, the flywheel 41, and the rotary body 42 are ωA, ωB, ωF, and ωR,
ωF=kAωA−kR1ωR (Eq. 7)
ωF=kBωB−kR2ωR (Eq. 8)
ωC=kRωR (Eq. 9)
where kA, kB, kR1, and kR2 are constants determined by the gear ratio of the differential mechanism, and kR is a constant determined by the gear ratio of the reduction gear set 12.
Further, as for the torque, the relationship among torque τA from the motor A 39 to the sun gear 43, torque τB from the motor B 40 to the sun gear 46, torque τF1 from the planetary gear 44 to the flywheel 41, torque τF2 from the planetary gear 47 to the flywheel 41, torque kR1 driving the ring gear 45, torque kR2 driving the ring gear 48, and torque τC of the crankshaft is as follows.
τF1=τA/kA=τR1/kR1 (Eq. 10)
τF2=τB/kB=τR2/kR2 (Eq. 11)
τC=(τR1+τR2)/kR (Eq. 12)
As can be clearly seen from the above equations, the velocities of the motors A 39 and the motors B 40 are controlled on the basis of information about rotational angle of the crankshaft 4 corresponding to the location of the slider 6 by a control circuit (not shown in the drawings), such that the velocity ωC of the crankshaft and the velocity ωF of the flywheel can be independently controlled. Further, as in the first embodiment shown in
In the third embodiment, since the two motors are respectively connected to the sun gears of the separate differential mechanisms, it is possible to reduce the size of the motors and rotate the motors at a high velocity. Further, it is possible to further reduce the size of the motor and the power amplifier by optimizing the gear ratios of the two differential mechanisms.
Further, in the third embodiment, it is also possible to drive the slider to have high performance and various functions, using the power from the commercial power source and the energy stored in the flywheel, by collaboratively driving plural motors, and achieve a small-sized press machine having high performance.
In
According to the fourth embodiment, it is possible to drive the load part, using the power from the commercial power source and the energy stored in the flywheel, by collaboratively driving plural motors having small capacities and provides a small-sized injection molding machine having high performance.
Although press machines and an injection molding machine are described in the above embodiment, the present invention is not limited thereto and may be applied to industrial machines requiring large torque. Further, even though the differential mechanism uses a planetary gear set in the above embodiments, other differential mechanisms may be used. Furthermore, an electric double layer capacitor or a chargeable battery, other than the condenser, may be used as the electric storage device. In addition, although two motors are used in the above embodiments, the present invention is not limited thereto.
The present invention may be modified different from the above embodiments without departing from the spirit and main characteristics. Therefore, the embodiments are nothing but simple embodiments and should not be limitedly construed. The scope of the present invention is described in the claims. Further, it should be understood that modifications and changes within the scope of the present invention are included in the present invention.
