Compensation converter and transformer

Abstract

To perform temperature compensation for temperature changes of a transformer without using an external power supply, and to enable accurate measurement and indication of speed with a simple circuit configuration.SOLUTION: A compensation converter 10 includes: a transformer TR in which a speed generator SMG is connected to a primary-side winding, and a speedometer SM is connected to a secondary-side winding via a fixed resistor R1-1 and a fixed resistor R1-2 connected closer to the speedometer SM than the fixed resistor R1-1, the fixed resistors R1-1 and R1-2 being connected in series; and a temperature compensation resistor Rt which has linear positive characteristics and connected in parallel with the fixed resistor R1-2 and the speedometer SM.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a compensated converter and a transformer. [Background technology]

[0002] Non-Patent Document 1 describes an inductor-type speedometer device that uses a transformer as one type of speedometer device that measures the speed of a vehicle. [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] Yoichi Kawai et al., "Recent Advances in Vehicle Speedometers," Hitachi Review, May 1964 Summary of the Invention [Problem to be solved by the invention]

[0004] FIG. 5 is a diagram showing an example of the configuration of a speedometer device 1a that uses a transformer.

[0005] As shown in FIG. 5, the speedometer device 1a includes a speed generator SMG, a compensation converter 10a, and a speedometer SM.

[0006] The tachometer generator SMG is connected to the vehicle wheels and outputs a signal (AC voltage) with a frequency corresponding to the rotational speed of the wheels. The compensation converter 10a converts the output signal of the tachometer generator SMG into a signal corresponding to that frequency and outputs it to the speedometer SM. Specifically, the compensation converter 10a outputs a number of pulses proportional to the frequency of the output signal of the tachometer generator SMG. The speedometer SM measures and indicates the wheel speed based on the output signal of the compensation converter 10a.

[0007] As shown in FIG. 5, the compensation converter 10a includes a primary-side limiting resistor R, a transformer TR, a fixed resistor R1, an adjusting resistor VR1, a wheel diameter compensation resistor VR2, and rectifiers Dd1 and Dd2.

[0008] The transformer TR is a saturable transformer. A saturable core with nearly rectangular magnetic characteristics (BH curve) is used as the core around which the windings are wound. A saturable core has the characteristic that the magnetic flux density reaches nearly the saturation magnetic flux density Bm with a slight magnetizing force, and thereafter, even if the magnetizing force increases, the magnetic flux density hardly changes at all. Therefore, when the magnitude of the primary input voltage is in the range sufficient to saturate the core, the average value of the half-cycle of the secondary output voltage is proportional only to the frequency of the primary input, and is unrelated to the magnitude of the voltage. Therefore, a signal proportional to the frequency of the input signal from the primary side is output from the secondary side of the transformer TR.

[0009] The primary winding of the transformer TR is connected in series with the speed generator SMG and the primary limiting resistor R. The primary limiting resistor R is a fixed resistor that limits the current to the primary winding of the transformer TR after the magnetic flux of the saturable transformer becomes saturated.

[0010] A speedometer SM is connected to the secondary winding of the transformer TR. Specifically, a fixed resistor R1, an adjustment resistor VR1, a wheel diameter compensation resistor VR2, and the speedometer SM are connected in series to the secondary winding of the transformer TR. The adjustment resistor VR1 is a variable resistor that compensates for individual differences in output that occur during the manufacturing process of the transformer TR. The wheel diameter compensation resistor VR2 is a variable resistor that compensates for fluctuations in the output of the transformer TR due to changes in wheel diameter caused by wear, etc. The connection order of the fixed resistor R1, the adjustment resistor VR1, and the wheel diameter compensation resistor VR2 is not limited to this, as long as the fixed resistor R1, the adjustment resistor VR1, the wheel diameter compensation resistor VR2, and the speedometer SM are connected in series to the secondary winding of the transformer TR. Rectifiers Dd1 and Dd2 are provided at both ends of the secondary winding of the transformer TR. The rectifiers Dd1 and Dd2 rectify both positive and negative half-waves of the AC voltage output from the transformer TR and output them to the speedometer SM. It should be noted that, for example, only one of the rectifiers Dd1 and Dd2 may be provided to rectify either the positive or negative half wave and output it to the speedometer SM.

[0011] As described above, compensation converter 10a converts the output signal of tachometer generator SMG (a pseudo-sine wave with a frequency corresponding to the wheel speed) into pulses whose number is proportional to the frequency of the signal, and outputs the converted pulses to speedometer SM. Because the response speed of speedometer SM to the output of compensation converter 10a is typically long, on the order of several milliseconds, speedometer SM indicates a value proportional to the average value of the output current of compensation converter 10a as the wheel speed. Therefore, the secondary side of transformer TR can be represented by an equivalent circuit, as shown in FIG. 6, in which the secondary-side output of transformer TR is replaced with a DC voltage source.

[0012] In the equivalent circuit shown in FIG. 6, the secondary output E of the transformer TR, which is equivalent to a DC voltage source, is expressed by the following equation (1). E=2kμSNBmfψ Equation (1)

[0013] In equation (1), k is the coupling coefficient that indicates the degree of coupling between the primary winding and the secondary winding, μ is the effective cross-sectional area ratio of the transformer TR core, S is the cross-sectional area of ​​the core, N is the number of turns of the secondary winding, Bm is the magnetic flux saturation density, f is the frequency of the input signal, and ψ is a correction coefficient that corresponds to the hysteresis curve of the saturable core. Ideally, ψ is 1.

[0014] Consider the case where the saturation magnetic flux density Bm changes due to a change in the temperature of the saturable core of the transformer TR in the equivalent circuit shown in Figure 6. When the temperature of the saturable core of the transformer TR rises, the saturation magnetic flux density Bm decreases, and as a result, according to equation (1), the secondary output E of the transformer TR decreases. Conversely, when the temperature of the saturable core of the transformer TR drops, the saturation magnetic flux density Bm increases, and as a result, according to equation (1), the secondary output E of the transformer TR increases.

[0015] On the other hand, because the resistance value of the entire circuit remains almost unchanged, changes in the secondary output E of the transformer TR directly result in changes in the value indicated by the speedometer SM. For this reason, temperature compensation is required to maintain the circuit current and correct the value indicated by the speedometer SM by changing the resistance value of the entire circuit in response to fluctuations in the secondary output E of the transformer TR due to temperature changes in the saturable core of the transformer TR.

[0016] One possible method for temperature compensation is to replace the fixed resistor R1 in FIG. 6 with a temperature-compensating resistor (e.g., a temperature sensor) whose resistance changes with temperature (see Non-Patent Document 1). This method requires the use of an element with a negative characteristic, i.e., a temperature-compensating resistor whose resistance decreases as the temperature increases and increases as the temperature decreases. An example of an element with a negative characteristic is a circuit using a thermistor and an operational amplifier. However, a circuit using an operational amplifier has a complex configuration and is therefore expensive. Furthermore, since an external power supply is required, this does not allow for the simple, low-cost configuration that does not require an external power supply, which is the greatest advantage of the present invention. Furthermore, a thermistor, which can be configured as a circuit without an external power supply, has a negative characteristic, but this characteristic is exponential. Therefore, even if a thermistor is used as a temperature-compensating resistor, it is difficult to achieve appropriate temperature compensation.

[0017] In view of the above problems, an object of the present invention is to provide a compensation converter and a transformer that can perform temperature compensation for temperature changes in the transformer without using an external power source and can accurately measure and indicate speed with a simple circuit configuration. [Means for solving the problem]

[0018] In order to solve the above problem, the compensation converter of the present invention is a compensation converter that converts the output signal of a tachograph, which outputs a signal of a frequency proportional to the rotational speed of a wheel, into a signal corresponding to the frequency and outputs the signal to a speedometer that indicates the wheel speed, and is equipped with: a transformer having the tachograph connected to its primary winding; and a secondary winding having the speedometer connected via a first fixed resistor connected in series with the secondary winding and a second fixed resistor connected on the speedometer side of the first fixed resistor; and a temperature compensation resistor with a linear positive characteristic connected in parallel with the second fixed resistor and the speedometer.

[0019] In the compensation converter according to the present invention, the temperature compensation resistor is embedded in the transformer.

[0020] In addition, in the compensation converter according to the present invention, a wheel diameter compensation resistor, which is a variable resistor for compensating for fluctuations in the output of the transformer in accordance with changes in the diameter of the wheel, and an adjustment resistor, which is a variable resistor for adjusting the output of the transformer, are further connected in series to the secondary winding of the transformer.

[0021] Furthermore, the transformer according to the present invention comprises a core, a coil member having a primary winding and a secondary winding wound around the core, a sealing member that seals the coil member with a molding material and has input / output terminals on one surface, a temperature sensor that is provided inside the sealing member, near the coil member, on the input / output terminal side as viewed from the coil member, and parallel to the coil member, and an insulating member that insulates the temperature sensor from the coil member. [Effects of the Invention]

[0022] The compensation converter and transformer according to the present invention perform temperature compensation for temperature changes in the transformer, enabling more accurate speed measurement. [Brief explanation of the drawings]

[0023] [Figure 1] FIG. 1 illustrates an example of a configuration of a compensation converter according to an embodiment of the present disclosure. [Figure 2] 2 is an equivalent circuit of the secondary side of the compensation converter shown in FIG. 1. [Figure 3] This is an equivalent circuit in which the end seen from A in the equivalent circuit shown in Figure 2 is replaced using the Thévenin-Hono theorem. [Figure 4A] 2 is a cross-sectional view showing an example of the configuration of the transformer shown in FIG. [Figure 4B] FIG. 2 is a view of the transformer shown in FIG. 1 as seen from one side on which input and output terminals are provided. [Figure 5] FIG. 10 is a diagram illustrating an example of the configuration of a compensation converter. [Figure 6] 6 is an equivalent circuit of the secondary side of the compensation converter shown in FIG. 5. DETAILED DESCRIPTION OF THE INVENTION

[0024] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0025] Fig. 1 is a diagram showing an example of the configuration of a speedometer device 1 according to an embodiment of the present disclosure. In Fig. 1, the same components as those in Fig. 5 are denoted by the same reference numerals, and description thereof will be omitted.

[0026] As shown in Fig. 1, the speedometer device 1 according to this embodiment includes a speedometer generator SMG, a compensation converter 10, and a speedometer SM. The speedometer device 1 according to this embodiment differs from the speedometer device 1a shown in Fig. 5 in that the compensation converter 10a has been replaced with a compensation converter 10. The compensation converter 10 converts the output signal of the speedometer generator SMG, which outputs a signal with a frequency proportional to the rotational speed of the wheels, into a signal according to the frequency, and outputs the signal to the speedometer SM, which indicates the wheel speed.

[0027] 1, the compensation converter 10 includes a primary-side limiting resistor R, a transformer TR, fixed resistors R1-1 and R1-2, an adjustment resistor VR1, a wheel diameter compensation resistor VR2, a temperature compensation resistor Rt, and rectifiers Dd1 and Dd2. The compensation converter 10 according to this embodiment differs from the compensation converter 10 shown in FIG. 5 in that the fixed resistor R1 is replaced with fixed resistors R1-1 and R1-2, and that a temperature compensation resistor Rt is added.

[0028] A speedometer generator SMG is connected to the primary side of the transformer TR via a primary-side limiting resistor R. A speedometer SM is connected to the secondary winding of the transformer TR via a fixed resistor R1-1 as a first fixed resistor, a fixed resistor R1-2 as a second fixed resistor, an adjustment resistor VR1, and a wheel diameter compensation resistor VR2. That is, in the compensation converter 10 according to this embodiment, the fixed resistor R1 shown in FIG. 5 is replaced with two fixed resistors, fixed resistors R1-1 and R1-2. The connection order of the fixed resistors R1-1, R1-2, adjustment resistor VR1, and wheel diameter compensation resistor VR2 is not limited to the order shown in FIG. 1. However, it is assumed that the fixed resistor R1-2 is connected closer to the speedometer SM than the fixed resistor R1-1.

[0029] As shown in Fig. 1, the temperature compensation resistor Rt is connected in parallel with the fixed resistor R1-2, the adjustment resistor VR1, the wheel diameter compensation resistor VR2, and the speedometer SM. As described above, the connection order of the fixed resistor R1-1, the fixed resistor R1-2, the adjustment resistor VR1, and the wheel diameter compensation resistor VR2 is not limited to the order shown in Fig. 1. In this embodiment, it is sufficient that the temperature compensation resistor Rt is connected in parallel with the fixed resistor R1-2, which serves as a second fixed resistor, and the speedometer SM.

[0030] The temperature compensation resistor Rt has a linear positive characteristic, and is, for example, a linear positive temperature coefficient resistor or a resistance temperature detector.

[0031] Figure 2 is an equivalent circuit on the secondary side of the transformer TR shown in Figure 1. In Figure 2, the current flowing through the fixed resistor R1-2 is defined as current I1, and the current flowing through the temperature compensation resistor Rt is defined as current I2.

[0032] When the temperature of the transformer TR rises and the secondary output E of the transformer TR drops, the output current (= I1 + I2) of the transformer TR decreases, but the temperature rise of the transformer TR also increases the temperature of the temperature compensation resistor Rt, and the resistance value of the temperature compensation resistor Rt also increases. The increase in the resistance value of the temperature compensation resistor Rt decreases the current I2, and as a result, the current I1 can be kept unchanged from before the temperature change of the transformer TR.

[0033] Also, when the temperature of the transformer TR decreases and the secondary output E of the transformer TR increases, the output current (= I1 + I2) of the transformer TR increases. However, due to the decrease in the temperature of the transformer TR, the temperature of the temperature compensation resistor Rt also decreases, and the resistance value of the temperature compensation resistor Rt also decreases. Due to the decrease in the resistance value of the temperature compensation resistor Rt, the current I2 increases. As a result, the current I1 can be made unchanged before and after the temperature change of the transformer TR.

[0034] Figure 3 is a diagram in which the equivalent circuit shown in Figure 2 is replaced with an equivalent circuit of the part seen from A using Thevenin's theorem.

[0035] When the temperature of the transformer TR rises, the secondary output E of the transformer TR decreases. However, due to the increase in the resistance value of the temperature compensation resistor Rt, the term A shown in Figure 3 increases. As a result, the current I flowing through the circuit increases. On the other hand, the term B shown in Figure 3 increases with the increase in the resistance value of the temperature compensation resistor Rt, and the current I decreases. Here, by setting the resistance values of each resistor so that (term B)·R1 - 1 << R1 - 2 + VR1 + VR2 + RL (resistance value of the speedometer SM), the amount of temperature compensation can be made to depend as little as possible on the resistance value of the adjustment resistor VR1 and the resistance value of the wheel diameter compensation resistor VR2.

[0036] In order to accurately perform temperature compensation following the temperature change of the saturable core of the transformer TR, the temperature sensor as the temperature compensation resistor Rt is preferably embedded in the transformer TR.

[0037] Figure 4A is a cross-sectional view of the transformer TR according to the present embodiment, and Figure 4B is a view of the transformer TR seen from one side.

[0038] As shown in Fig. 4A, the transformer TR includes a coil member 23 having a saturable core 21 and a winding 22 (primary winding and secondary winding) wound around the saturable core 21. The transformer TR further includes a sealing member 24. The sealing member 24 seals the coil member 23 with a molding material. The sealing member 24 is made of, for example, a molding material using an acid anhydride as the resin and a filler as the hardener. A plurality of input / output terminals 25 for the transformer TR are provided on one surface 24A of the sealing member 24.

[0039] As shown in FIG. 4B, six input / output terminals 25 (terminals 25-1 to 25-6) are provided on one surface 24A of the sealing member 24. Terminals 25-1 and 25-2 are connected, for example, to one end and the other end of the primary winding. Terminals 25-3 and 25-4 are connected, for example, to one end and the other end of the secondary winding. Terminals 25-5 and 25-6 are connected, for example, to one end and the other end of a temperature sensor 26 (one end (on the fixed resistors R1-1 to R1-2 side) and the other end (on the GND side) of a temperature compensation resistor Rt shown in FIG. 1) which will be described later.

[0040] 1, and has a linear positive characteristic. As shown in FIG. 4A, the temperature sensor 26 is provided inside the sealing member 24. Furthermore, the temperature sensor 26 is provided in the vicinity of the coil member 23, on the input / output terminal 25 side as viewed from the coil member 23, and in parallel to the coil member 23.

[0041] In the speedometer device 1 shown in Fig. 1, the energy generated by the tachometer generator SMG is significantly greater than the energy consumed by the speedometer SM. Therefore, most of the energy generated by the tachometer generator SMG is consumed by the primary-side limiting resistor R. Due to the energy consumption by the primary-side limiting resistor R, the primary-side limiting resistor R generates heat, and this heat is transferred to the transformer TR by convection through the space and the sealing member 24, and conduction through the input / output terminals 25 connected to the primary winding, thereby contributing to a rise in temperature of the saturable core 21 of the transformer TR.

[0042] To mitigate the above-mentioned convection-induced temperature rise of the transformer TR, it is preferable that the sealing member 24 has a certain thickness. This has the secondary effect of easing the temperature change of the saturable core 21 of the transformer TR in response to a sudden change in the outside air temperature.

[0043] As in this embodiment, by providing a temperature sensor 26 inside the sealing member 24, near the coil member 23, on the input / output terminal 25 side as viewed from the coil member 23, and parallel to the coil member 23, the temperature sensor 26 is able to improve its ability to follow the temperatures of the coil member 23 and the saturable core 21, enabling highly accurate temperature compensation.

[0044] 4A, an insulating member 27 is provided around the temperature sensor 26 to insulate the temperature sensor 26 from the coil member 23. The insulating member 27 is made of, for example, a silicon glass tube, and is provided so as to cover the periphery of the temperature sensor 26. In this way, the temperature sensor 26 and the coil member 23 can be insulated from each other.

[0045] As described above, the compensation converter 10 according to this embodiment includes a transformer TR having a primary winding connected to a speedometer generator SMG and a secondary winding connected to a speedometer SM via a fixed resistor R1-1 (first fixed resistor) connected in series with the secondary winding and a fixed resistor R1-2 (second fixed resistor) connected on the speedometer SM side of the fixed resistor R1-1, and a temperature compensation resistor Rt having a linear positive characteristic connected in parallel with the fixed resistor R1-2 and the speedometer SM.

[0046] When the output current of the transformer TR increases (decreases) due to an increase (decrease) in the temperature of the transformer TR, the temperature compensating resistor Rt has a linear positive characteristic, so the resistance value of the temperature compensating resistor Rt increases (decreases) due to an increase (decrease) in the temperature of the temperature compensating resistor Rt, and the current flowing through the temperature compensating resistor Rt decreases (increases). As a result, the current flowing through the speedometer SM remains unchanged from before the temperature change in the transformer TR, allowing for temperature compensation for the temperature change in the transformer TR and enabling more accurate speed measurements. In addition, there are many inexpensive, high-precision temperature compensating resistors Rt with linear positive characteristic available commercially, making circuit design easier.

[0047] Although the above-described embodiments have been described as typical examples, it will be apparent to those skilled in the art that many modifications and substitutions are possible within the spirit and scope of the present invention. Therefore, the present invention should not be construed as being limited by the above-described embodiments, and various modifications and changes are possible without departing from the scope of the claims. [Explanation of symbols]

[0048] 1 Speedometer device 10 Compensation Converter 21 Saturable Core 22 windings 23 Coil material 24 Sealing member 25,25-1,25-2,25-3,25-4,25-5,25-6 Input / output terminal 26 Temperature Sensor 27 Insulating materials SMG Speed ​​Generator TR transformer SM speedometer R Primary side limiting resistor R1-1 Fixed resistor (first resistor) R1-2 Fixed resistor (second resistor) VR1 adjustment resistor VR2 Wheel diameter compensation resistance Dd1,Dd2 Rectifier

Claims

1. a compensation converter that converts an output signal of a tachograph that outputs a signal of a frequency proportional to the rotational speed of a wheel into a signal corresponding to said frequency and outputs the signal to a speedometer that indicates the speed of said wheel, a transformer having a primary winding connected to the tachometer generator and a secondary winding connected to the speedometer via a first fixed resistor connected in series with the secondary winding and a second fixed resistor connected closer to the speedometer than the first fixed resistor; a temperature compensation resistor having a linear positive characteristic, connected in parallel with the second fixed resistor and the speedometer;

2. 2. The compensation converter according to claim 1, The temperature compensation resistor is embedded in the transformer.

3. 3. A compensation converter according to claim 1 or 2, a wheel diameter compensation resistor, which is a variable resistor for compensating for fluctuations in the output of the transformer in accordance with changes in the diameter of the wheel, and an adjustment resistor, which is a variable resistor for adjusting the output of the transformer, further connected in series to the secondary winding of the transformer;

4. a coil member including a core and a primary winding and a secondary winding wound around the core; a sealing member that seals the coil member with a molding material and has input / output terminals provided on one surface thereof; a temperature sensor provided inside the sealing member, near the coil member, on the input / output terminal side as viewed from the coil member, and parallel to the coil member; an insulating member that insulates the temperature sensor from the coil member.

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