JPS6350952B2 - - Google Patents

Abstract

PURPOSE:To obtain a constant torque without any complicated control by using an iron steel material which contains carbon and silicon contents in the prescribed values or lower for a material of an outer rotor. CONSTITUTION:A load device of an ergometer has an outer rotor 5, an inner stator 7, a plurality of exciting coils 8 provided in the inner stator, and a current source for energizing the coils 8. The rotor 5 is formed of an iron steel material which contains 0.12% or lower of carbon content and 0.35% or lower of silicon content. Further, a current command signal is generated in response to the output of instructing means in a circuit 9, and a current supplied to the exciting coils is controlled in response to the output of the current command signal. Thus, excellent constant torque property can be obtained.

Description

[Detailed description of the invention]

The present invention relates to a loading device for an ergometer. One of the ergometers available on the market is the Monarch ergometer. This device consists of a flywheel that is driven by the bending and stretching movements of the legs, and a belt that applies a load to the flywheel using frictional force.The amount of load is adjusted by a weight attached to the tip of the belt. . This device can directly measure the amount of load by applying weight as long as the flywheel has a constant rotation speed, so it can obtain accurate data when measuring physical strength, but it is time consuming, the device is large, and adjustment is complicated. . Also, ergometers equipped with electrical load means have recently been offered on the market. One of these is equipped with a flywheel manufactured from gray cast iron, a rotation sensor for detecting the number of revolutions of the flywheel, and a strain gauge for detecting torque.The output of the strain gauge and the rotation of the flywheel are There is a device that obtains a constant torque by controlling the current supplied to an electromagnetic brake device based on the correlation with several outputs. In another configuration, the relationship among the flywheel rotational speed, torque, and control current value described above is calculated and determined in advance by a computer, etc., and stored in a storage device, and the flywheel is There is a device that obtains a constant torque by determining the current to be passed through the braking coil based on the rotational speed of the brake and the target braking force. Of these two devices, since the former is equipped with a mechanical torque detection means, it is complicated to make adjustments before starting use or as the device changes over time. Furthermore, the latter requires complicated calculations to be performed in advance, and requires a separate storage device to store the results of these calculations as data. These devices obtain constant torque by complex electrical control of the load means. Furthermore, since both of them are configured with an inner rotor and an outer stator, the outer rotor in which the excitation coil is disposed becomes large, which in turn increases the size of the entire load device, and the inner rotor becomes hot. Therefore, the present invention was made in view of the above-mentioned drawbacks, and focuses on the mechanical structure of the eddy current brake of the load means, and it is an object of the present invention to obtain a nearly constant torque in the practical rotational speed range of the load device. It is an object of the present invention to provide a load device for an ergometer that can obtain a constant load value using a simple control method. The above-mentioned object is a load device for an ergometer that includes an outer rotor, an inner stator, a plurality of excitation coils provided in the inner stator, and a current source for energizing the excitation coil. The rotor is made of steel material with a carbon content of 0.12% or less and a silicon content of 0.35% or less, and further includes an indicating means for indicating a desired load value, and a means for indicating a desired load value in response to the output of the indicating means. a square root characteristic signal generation circuit that generates a command signal corresponding to the current; and a constant current drive circuit provided between the excitation coil and the current source to control the current supplied to the coil in response to the output of the generation circuit. This can be achieved by configuring an ergometer loading device equipped with. In addition, in the above configuration, the outer rotor has a concentric structure made of two types of steel materials, and the rotor material for the circumferential portion is structural carbon steel pipe (STK or STKM).
It is preferable to use a steel pipe that satisfies the above-mentioned content selected from the above and insert it into the outer peripheral rotor made of cast iron material. Further, when the outer circumferential portion is merely intended to provide a flywheel effect to the inner circumferential portion, the outer circumferential portion may be made of a non-ferrous metal member such as cement. With the above configuration, the eddy current brake is controlled by supplying current to the excitation coil in response to the signal from the signal generation circuit having square-law characteristics, thereby eliminating the need for any complicated control. It is possible to provide a load device that can obtain constant torque. Furthermore, since the load device of the present invention can significantly reduce the excitation current value of the load device at the same load value compared to conventional load devices, the device can be miniaturized with less heat generation. The present invention will be explained in detail below using the accompanying drawings. The present inventors conducted intensive research on the characteristics of eddy current brakes and found that among various parameters, specific resistance and magnetic permeability are greatly involved in material characteristics. The present inventors focused on the above-mentioned specific resistance (Ω・cm) and magnetic permeability (H/m), created flywheels from various materials, and measured the relationship between the braking force and the excitation current of the excitation coil. . This result is the first
Shown as a diagram. In the figure, brake force-excitation current characteristic curves of flywheels made of pure iron, cast steel, and conventional gray cast iron are shown. The pedal rotation speed of the load device at this time was 50 rpm. In this case, the gear ratio is set to 15, so the flywheel is at 750 rpm. As can be easily understood from the figure, flywheels made of pure iron can obtain high loads with low current values, followed by flywheels made of cast steel, and flywheels whose performance is incomparably worse than these two. This is a conventionally used flywheel made of gray cast iron. Therefore, it can be concluded that pure iron or cast steel is preferable for the flywheel material. Furthermore, the inventors investigated the relationship between the components of the iron materials used and braking characteristics, and found that Si
(Silicon) content is related to specific resistance,
It was found that the smaller the amount, the smaller the specific resistance, and that the carbon content is related to magnetic permeability, and that the smaller the amount, the higher the magnetic permeability.
Table 1 shows the results of analyzing the components of each flywheel.

[Table] Therefore, the present inventors have found that when configuring an eddy current brake for a load device, by specifying the composition of the flywheel material, it is possible to obtain a large load with excellent characteristics and a small current. I came to the conclusion that it is possible. According to this conclusion, if the flywheel is constructed using pure iron, which has the lowest carbon and silicon content among iron materials, it is possible to obtain the best characteristics and the maximum load value with a small current. However, since pure iron is difficult to obtain on the market and is expensive, the inventors manufactured a flywheel using cast steel, which has properties similar to those of pure iron, and found that the properties were almost satisfactory. I was able to get In this case, considering the rotational torque of the flywheel and the ease of availability in the market, we will use structural carbon steel pipes that are easily available in the market (STK or STK in JIS).
STKM (specified as STKM) is the inner part facing the excitation coil, and in order to create a flywheel effect on the outer part, even if the outer part is made of gray cast iron, the whole part is made of cast steel. It was found that almost the same results were obtained. However, in this case, JIS only sets an upper limit for the composition of structural carbon steel pipes called STK or STKM, so if the above structural carbon steel pipes are used, they must be manufactured as standard products. A steel pipe that satisfies or matches the desired carbon and silicon content conditions must be selected from among the steel pipes. As an example, a flywheel made of conventional gray cast iron is assumed to be type A, and the circumferential side facing the excitation coil is selected from STK-50, and its content is (C = 0.12% or less, Si = 0.35% or less). A concentric double structure whose outer periphery was made of the above-mentioned gray cast iron was designated as B, and the characteristics of each are shown in FIGS. 3 to 9. FIGS. 3 and 4 show the W-I _s characteristics of the eddy current brakes according to the prior art and the present invention. As shown in Fig. 1, when using the flywheel according to the present invention, a larger load force can be obtained at the same applied current value, and there is a difference between the load values at each rotation speed. is small, and the curve can be approximated by a squared curve.
In particular, in Figure 3, the curve at 40 rpm deviates considerably from the other curves. FIGS. 5 and 6 show the torque-rotational speed characteristics of the eddy current brakes according to the prior art and the present invention. Table 2 shows a comparison of the current value and torque variation ranges, assuming that the practical rotation speed range of the pedal of a load device using an eddy current brake is 40 to 60 rpm.

[Table] As can be easily understood from the above comparison, the flywheel configuration of the load device according to the present invention is different from the conventional one in the practical rotational speed range of the flywheel pedal when the current value of the excitation coil is constant. The fluctuation is much smaller than in the example, and a high output load can be obtained. FIGS. 7 and 8 show torque-excitation current characteristics based on each rotation speed. The shaded area in the figure shows the fluctuation range of the rotational speed and torque within the practical rotational speed, and is a portion that must be compensated for by further controlling the current value to maintain an accurate constant load. be. Assuming that the torque is within the practical range of 38.8 Kg-cm, which is the point of 300 W at 50 rpm, the shaded area shown in FIG. 8 is almost negligible compared to the shaded area shown in FIG. 7. This means that the eddy current brake using the flywheel of the present invention can obtain constant torque characteristics in a practical range with approximately square characteristics of the excitation current without correction by a special compensation circuit from the outside. FIG. 9 is a diagram showing an ergometer 10 using the loading device of the present invention, in which a user rides on the saddle 1, places his feet on the pedals 2, and performs bending and stretching exercises while gripping the handlebars 3. According to
The driving force of the pedal is transmitted from the gear on the pedal shaft to the transmission 4 via a chain, etc., and after being suitably shifted here, it is transferred to the outer rotor 5.6 via a belt etc.
has been communicated to. The flywheel of the eddy current brake of the load device has a concentric double structure, with the outer rotor 5 made of conventional gray cast iron and the inner rotor 6 made of structural carbon steel pipe (STK-50). Carbon content 0.12% or less, silicon content 0.35%
The following selected steel pipes are internally fitted, and a stator 7 is disposed on a concentric circle inside the inner rotor 6. Inside the stator 7, as shown,
Six excitation coils 8 are provided radially.
These plural excitation coils are connected in series with each other, and both ends of the feeder line for supplying current are connected to a constant current drive circuit 9. The circuit 9 is a D-A circuit that converts the digital value indicated by the user's load value using the numeric keypad of the input/output box 11 into an analog value.
a converter, a square root function generator that generates the square root as a supply current command value based on the output of the D-A converter, and a constant current that controls the supply current from the power supply to the exciting coil in response to the output of the generator. It consists of a drive circuit. Furthermore, a current source for energizing the excitation coil is connected to the current drive circuit. As described above, the ergometer load device according to the present invention is significantly superior to conventional ones by keeping the carbon and silicon content of the material of the flywheel of the eddy current brake below a certain value. It is possible to obtain a constant torque characteristic, and the control current characteristic can be approximated by approximately the square, so there is no need to use a complicated control method as in the past, and it is possible to simply use the control method based on the square root of the command value from the input means. With only a signal, within the practical rotation speed range of the pedal,
Load devices can be controlled. In addition, the eddy current brake of the load device of the present invention has the following features compared to the conventional one:
Since high loads can be obtained with the same control current,
Generates little heat, so there is no need to consider heat radiation.
This allows the device to be made smaller. In addition, since the outer rotor of gray cast iron and the inner rotor of structural carbon steel pipe are used as flywheel materials, they are easily available on the market and are inexpensive. In particular, in the present invention, by using an inner stator and an outer rotor, the heating element rotates, so that heat is radiated by convection due to the rotation of the rotor. In the above configuration, the outer rotor may be made of a non-ferrous metal material, such as concrete, for the purpose of simply imparting a flywheel effect to the inner rotor. Furthermore, although not described in detail in the present invention, the present invention is further provided with a torque detecting means such as a strain gauge, and the output thereof is input to a microcomputer for calculation correction. We can provide a suitable ergometer. Furthermore, when expanding the practical rotational speed range, it is advisable to perform rotational speed correction.

[Brief explanation of drawings]

Fig. 1 is a diagram showing the braking force-exciting current characteristics depending on the material of the flywheel, Fig. 2 is a diagram showing the braking force-exciting current characteristic of pure iron, and Fig. 3 is a diagram showing the braking force-exciting current characteristics of pure iron.
4 and 4 are diagrams showing the W-Is characteristics of the conventional and the present invention, FIGS. 5 and 6 are diagrams showing the torque-rotational speed characteristics of the conventional and the present invention, and FIG. 7 and FIG. FIG. 8 is a diagram showing the torque-excitation current characteristics of the conventional and the present invention, and FIG. 9 is an example of an ergometer equipped with a load device according to the present invention. (Symbols in the figure), 1: Saddle, 2: Pedal, 3:
Handle, 4: Transmission, 5: Outer rotor, 6:
Inner circumferential rotor, 7: Stator, 8: Excitation coil,
9: constant current drive circuit, 10: bicycle ergometer, 11: input/output box.

Claims (1)

[Claims] 1. A load device for an ergometer comprising an outer rotor, an inner stator, a plurality of excitation coils provided in the inner stator, and a current source for energizing the excitation coils. , the outer rotor is made of a steel material with a carbon content of 0.12% or less and a silicon content of 0.35% or less, and further includes an indicating means for indicating a desired load value, and a desired load value in response to the output of the indicating means. a square root characteristic signal generation circuit that generates a current command signal corresponding to a load value; and a constant current provided between an excitation coil and a current source to control the current supplied to the coil in response to the output of the generation circuit. An ergometer load device comprising a drive circuit. 2 The outer rotor has a concentric structure made of two types of steel materials, and the inner rotor material is a steel pipe that satisfies the above content selected from structural carbon steel pipes (STK or STKM), and is made from cast iron material. The load device for an ergometer according to claim 1, wherein the load device is inserted into an outer peripheral rotor. 3. The outer rotor having the concentric structure has an outer circumferential portion made of any non-ferrous material (concrete), and a flywheel effect is imparted to the inner circumferential portion. Ergometer loading device. 4. According to any one of the above claims, further comprising a torque detection means such as a strain meter, and the output of the characteristic signal generation circuit is corrected and inputted to the current control circuit. ergometer loading device.