JP6075203B2 - Rotating machine with physical quantity measuring device - Google Patents

Description

  The present invention provides, for example, a hub constituting a rolling bearing unit for supporting a wheel of an automobile, a main shaft constituting a machine tool such as a lathe, a milling machine, and a machining center, and a rotating shaft constituting various rotating machines such as a gear shaft constituting a transmission. The present invention relates to an improvement in a rotating machine with a physical quantity measuring device having a function of measuring a physical quantity such as a displacement and an inclination generated in a member, and a load and a moment acting on the rotating member.

  In order to make the control for ensuring the running stability of the car more sophisticated, it is considered to incorporate a physical quantity measuring device into the rolling bearing unit for supporting the wheel of the car and measure the axial load applied to each wheel. (For example, refer to Patent Document 1). 4 to 6 show an example of a conventional structure of a rotating machine with a physical quantity measuring device described in Patent Document 1 and the like and conventionally known. This conventional structure is a hub that is a rotating member that rotates together with the wheel while being supported and fixed to the inner diameter side of the outer ring 1 that is a stationary member and does not rotate even when used while being supported by the suspension device. 2 is rotatably supported via a plurality of rolling elements 3 and 3. A preload is applied to each of the rolling elements 3 and 3 together with contact angles that are opposite to each other (in the illustrated case, a rear combination type).

  The inner end of the hub 2 in the axial direction ("inner" with respect to the axial direction refers to the center in the width direction of the vehicle when assembled to the automobile, and is the right side of Fig. 4. On the other hand, The left side of FIG. 4, which is the outer side in the width direction, is referred to as “outside” in the axial direction. The same applies throughout this specification), and the cylindrical encoder 4 is supported and fixed concentrically with the hub 2. A pair of sensors 6 a and 6 b are supported inside a bottomed cylindrical cover 5 that closes the inner end opening of the outer ring 1, and the detection parts of both the sensors 6 a and 6 b are connected to the encoder 4. The outer peripheral surface, which is the detection surface, is placed close to and facing.

Of these, the encoder 4 is made of a magnetic metal plate such as a steel plate in a cylindrical shape, and has a plurality of through-holes 7 and 7 formed at equal intervals in the circumferential direction in the intermediate portion in the axial direction. Yes. The shape of each of the through holes 7 and 7 is a “<” shape in which both side portions with the intermediate portion as a boundary are inclined in opposite directions with respect to the width direction with respect to the axial direction of the encoder 4. Therefore, on the outer peripheral surface of the encoder 4 which is a detection surface, portions corresponding to the through holes 7 and 7 having different magnetic characteristics (first characteristic portions), and the through holes 7 and 7. The portions (second characteristic portions) sandwiched between them are alternately arranged in the circumferential direction. And the detection part of both said sensors 6a and 6b is each made to oppose and adjoin to the width direction (axial direction) both-sides part which pinched | interposed the said "<"-shaped bending part among this to-be-detected surface. Further, the A phase pulse signal S _A which is the output signal of one sensor 6a and the B phase pulse signal S _B which is the output signal of the other sensor 6b are made equal to each other (T _A = T _B ). ing. At the same time, the outer ring 1 and the hub 2 are not relatively displaced with respect to the phase difference δ between the two pulse signals S _A and S _B (the axial load is not acting on the hub 2). As shown in FIG. 6A, the initial phase difference δ ₀ , which is the phase difference δ in FIG. For this purpose, the configurations and relative positions of the sensors 6a and 6b and the encoder 4 are restricted.

In the case of the conventional structure configured as described above, an axial load acts between the outer ring 1 and the hub 2 when the wheel rotates, so that the outer ring 1 and the hub 2 are relatively displaced in the axial direction. Along with this, when the scanning position of the detected surface of the encoder 4 is changed in the axial direction by the detection units of the sensors 6a and 6b, for example, as shown in the order of (A) → (B) in FIG. The phase difference δ changes. Here, the phase difference ratio (= phase difference δ / pulse period T _A ), which is the ratio between the phase difference δ and the pulse period T _A of the A-phase pulse signal S _A , is not affected by the rotational speed. It is a dimensionless amount and takes a value commensurate with the axial load (relative displacement in the axial direction). Therefore, based on the phase difference ratio [delta] / T _A, it can be calculated the axial load (axial direction of the relative displacement). In the conventional structure described above, the phase difference ratio δ / T _A exceeds the range (0 <δ / T _A <1) sandwiched between 0 and 1 with 0.5 as the center during operation. It is designed not to be. Actually, it is designed to change within a range narrower than this range. In any case, the calculation process as described above is performed by a calculator (not shown). Therefore, this calculator, had been investigated in advance by theoretical calculation and experiment, the relationship between the phase difference ratios [delta] / T _A and the axial load (axial direction of the relative displacement), equation or a map or the like of Incorporate in the form.

When the conventional structure as described above is implemented, a microcomputer or the like can be used as the arithmetic unit. In this case, a reference clock signal is used for measuring the phase difference δ and the pulse period T _A. That is, when the phase difference δ is measured, for example, the rising edge of the A-phase pulse signal S _A is detected, and simultaneously, the counter starts counting the number of pulses of the reference clock signal, and the B-phase pulse simultaneously stops counting and detection of the rising edge of the signal S _B. Then, the phase difference δ is measured by reading the count value at this time. Even for the pulse period T _A , the measurement is performed in the same manner using another counter. In any case, if the count value of the counter is cleared at the same time as the count value is read (reset to 0), the measured quantity (phase difference δ, pulse period T _A ) related to the target pulse signal Can be measured sequentially.

However, each counter normally has a finite bit width (counter length), and therefore overflows when the count value reaches the upper limit of the bit width. As a countermeasure in this case, a method of detecting the occurrence of overflow and correcting the count value is conceivable. However, when this method is adopted, the processing becomes complicated, and depending on the timing of interrupt processing, a large measurement error may occur. May occur. Therefore, in order to avoid such inconvenience, the frequency of the reference clock signal (reference clock frequency) is set to a value that does not cause the overflow within the time corresponding to the measured quantity (δ, T _A ). Must be set to
On the other hand, from the viewpoint of increasing the resolution of the phase difference δ, it is desirable that the reference clock frequency be as high as possible in order to sufficiently ensure the resolution of the physical quantity to be measured (axial load, relative displacement in the axial direction). .

  In this regard, in the case of the wheel-supporting rolling bearing unit described above, the rotational speed range in which the physical quantity is to be measured is, for example, 5 km / h or more and the maximum speed (for example, 200 km / h) in terms of the traveling speed of the automobile. As said below, it is a fairly wide range. For this reason, when the reference clock frequency is set to be lower (lower) than a value at which the overflow does not occur at the lowest rotation speed (speed at which the time width corresponding to the phase difference δ is longest) in the rotation speed range. When the rotational speed becomes high (when the time width corresponding to the phase difference δ becomes short), the count value indicating the amount of change in the phase difference δ becomes small, and the resolution of the phase difference δ is sufficient. It will be difficult to secure.

This point will be described in more detail as follows. Now, it is considered that the phase difference δ has changed by 10 degrees from the initial phase difference δ ₀ (| δ−δ ₀ | = 10 degrees) with a change in the physical quantity to be measured. In this case, assuming that the count value of the counter corresponding to 10 degrees is 100 at a certain low rotational speed, the resolution of the phase difference δ at the rotational speed is 10 degrees / 100. = 0.1 degrees. On the other hand, in the same case, the time width corresponding to 10 degrees is shorter at a high rotational speed than at the low speed described above. The count value also decreases. For example, assuming that the count value at this time is 20, the resolution of the phase difference δ at the rotation speed is 10 degrees / 20 = 0.5 degrees. In this way, even when the same phase difference δ changes, if the rotational speed is different, the time width corresponding to the change in the phase difference δ changes (the higher the rotational speed, the shorter the time width). The resolution of the phase difference δ changes (the resolution decreases as the rotational speed increases). Therefore, when the rotation speed range in which the physical quantity is to be measured is wide, such as the wheel support rolling bearing unit described above, the overflow is caused by setting the reference clock frequency to the lowest rotation speed in the rotation speed range. If it is set to a value that does not occur, the count value representing the amount of change in the phase difference δ becomes small when the rotational speed is high, and it is difficult to ensure sufficient resolution of the phase difference δ.

  Such a problem is not limited to the conventional structure described above, but a method for measuring physical quantities based on the same principle as the conventional structure, that is, a pulse included in the output signal of a pair of sensors opposed to the detection surface of the encoder. This can also occur in other structures that employ a method of measuring physical quantities using the time width of As an example of such another structure, Patent Document 2 includes an example in which the measurement method is employed in a spindle device of a machine tool, and Patent Document 3 includes an example in which the measurement method is employed in an automobile transmission. Each is listed. These spindle devices and transmissions are also required to perform the physical quantity measurement as described above over a wide rotational speed range. For this reason, inconveniences such as those described above occur.

JP 2006-317420 A JP 2011-75346 A JP 2012-98268 A

  In view of the circumstances as described above, the present invention increases the bit width of a counter for measuring a measured quantity related to a pulse signal necessary for calculating a physical quantity under the condition that the counter does not overflow during operation. The invention was invented to realize a structure capable of improving the resolution of the measured quantity (resolution of the physical quantity) in the entire rotational speed range in which the physical quantity should be measured, including a high rotational speed. is there.

  The rotating machine with a physical quantity measuring device of the present invention is fixed to the rotating member, a stationary member that does not rotate during use, a rotating member that is rotatably supported by the stationary member by a plurality of rolling bearings, An encoder having a detection surface concentric with the rotating member, the characteristics of the detection surface being alternately changed in the circumferential direction, and the stationary member in a state where the respective detection portions are opposed to the detection surface. The pulse signal corresponding to the characteristic change of the supported part where both the detection parts face each other [the binary signal {"H" ("1") and "L" ("0")) A pair of sensors generated as output signals, and using the output signals of both sensors, the displacement of the rotating member relative to the stationary member, and between the stationary member and the rotating member With the load acting on Chino and a computing unit for obtaining at least one physical quantity.

In particular, in the case of the rotating machine with a physical quantity measuring device of the present invention, the initial phase difference between the output signals of the two sensors is 180 degrees in a neutral state where the stationary member and the rotating member are not relatively displaced. Is set. The computing unit calculates an exclusive OR between the output signals of both the sensors, and a ratio between the pulse width of the signal representing the exclusive OR and the pulse period of the output signals of both the sensors. The physical quantity is calculated based on the pulse width ratio.
That is, in the case of the present invention, the pulse width is employed as the measured amount related to the pulse signal necessary for calculating the physical quantity, instead of the phase difference employed in the above-described conventional structure.
In the case of the present invention, the computing unit sets the pulse width and the pulse period in a state where the reference clock frequency for measuring the pulse width is higher than the reference clock frequency for measuring the pulse period. measure.

When carrying out the physical quantity measuring device with a rotary machine of the above such present invention, preferably, the pulse width used for obtaining the prior SL pulse width ratio, of the signal representing the XOR of the signal The pulse width indicates the time when the value is L.

Further, when practicing the present invention, more preferably, a pre-Symbol calculator, based on the neutral state, the relative one of the output signals of the sensors of both sensor, the other sensor output signal phase It has a function of obtaining the direction of relative displacement of the rotating member with respect to the stationary member based on whether the movement is delayed or advanced.
In this case, specifically, For example, in the pulse edge at the same time the output signal of the one sensor, based on the value of the output signal of the other sensor as a reference to the neutral state, the It is determined whether the phase of the output signal of the other sensor is delayed or advanced with respect to the output signal of one sensor.

  According to the rotating machine with a physical quantity measuring device of the present invention configured as described above, the counter for measuring the measured quantity related to the pulse signal necessary for calculating the physical quantity is set so that the counter does not overflow during operation. In the case of the conventional structure described above, the resolution of the measured quantity (the resolution of the physical quantity) in the entire rotational speed range in which the physical quantity is to be measured, including a high rotational speed, without increasing the bit width of It can be improved compared to Hereinafter, this reason will be described.

In the case of the present invention, as in the conventional structure described above, the phase difference ratio (phase difference) is the ratio between the phase difference between the output signals of a pair of sensors and the pulse period of the output signals of both sensors. Instead of calculating the physical quantity based on the pulse period), an exclusive OR between the output signals of the pair of sensors is calculated, the pulse width of the signal representing the exclusive OR, A physical quantity is calculated based on a pulse width ratio (pulse width / pulse period) which is a ratio with the pulse period of the output signal.
Here, when the rotation speed of the rotating member is the same, the pulse periods that are the denominators of the pulse width ratio and the phase difference ratio are the same (same time width), but the physical quantity is The maximum value of the pulse width, which is a numerator of the pulse width ratio, which changes in response, is smaller than the maximum value of the phase difference, which is the numerator of the phase difference ratio (the time width is shortened). In particular, as a pre-Symbol pulse width is a molecule of the pulse width ratio, of the signal representing the XOR, the use of the pulse width value of this signal indicates the time which is L, the maximum value of the pulse width , Less than half of the maximum value of the phase difference. Therefore, if the bit width of the counter for measuring the pulse width and the bit width of the counter for measuring the phase difference are the same as each other, under the condition that these counters do not overflow during operation. the reference clock frequency for measuring the pulse width, it is Ru can be higher than the reference clock frequency for measuring the phase difference. On the other hand, the change amount of the pulse width (time width) and the change amount of the phase difference (time width) accompanying the change of the physical quantity are equal to each other. Therefore, the count value corresponding to the change amount of the pulse width can be made larger than the count value corresponding to the change amount of the phase difference.
As a result, in the case of the present invention, the measured quantity (the pulse width in the case of the present invention and the phase difference in the case of the above-described conventional structure) related to the pulse signal necessary for calculating the physical quantity is measured. The resolution of the measured quantity in the entire rotational speed range in which the physical quantity is to be measured, including a high rotational speed, without increasing the bit width of the counter, under the condition that the counter does not overflow during operation. (Resolution of the physical quantity) can be improved as compared to the conventional structure described above.

  Note that the accuracy of the pulse edges of the output signals of both sensors changes due to the edge error of these sensors. For example, when each of these sensors is a magnetic sensor, it is known that even if the same magnetic field change is given, a variation in normal distribution occurs in the timing of the generated pulse edge. If the count value of the counter corresponding to the change amount of the measured amount is small with respect to this variation, the measurement error of the change amount of the measured amount (the measurement error of the physical quantity) increases accordingly. In this regard, in the case of the present invention, as can be seen from the above description, the count value corresponding to the amount of change in the measured amount can be made larger than in the case of the conventional structure described above. For this reason, it is possible to improve the measurement accuracy of the change amount of the measurement target (measurement accuracy of the physical quantity) as compared with the conventional structure described above.

Further, according to the present invention, for example, the above-described configuration is adopted in which the bit width of the counter for measuring the pulse width and the bit width of the counter for measuring the pulse period are made equal to each other. The effects of the present invention can be exhibited.

Further , when the configuration as described in the above paragraph [0016] is adopted , the relative displacement direction (the direction of the physical quantity to be measured) of the rotating member with respect to the stationary member during operation is 2 in the normal direction and the reverse direction. When the present invention is applied to a structure that changes in a direction, it is determined whether the direction of the relative displacement is a forward direction or a reverse direction.

The block diagram for demonstrating the calculation process of the physical quantity by a computing unit which shows an example of embodiment of this invention. The diagram which shows the output signal of a pair of sensor, and the signal showing the exclusive OR of these both output signals. FIG. 3 is a diagram similar to FIG. 2 for explaining a method of determining whether the phase of the output signal of the other sensor is delayed or advanced with respect to the output signal of one sensor with reference to the neutral state. Sectional drawing which shows an example of a conventional structure. FIG. 3 is a development view of a part of a detected surface of the encoder. The diagram which shows the output signal of a pair of sensor with a neutral state (A) and a non-neutral state (B).

  An example of an embodiment of the present invention will be described with reference to FIGS. The feature of this example is mainly in the configuration of an arithmetic unit that performs a physical quantity calculation process. Since the structure and operation of other parts are the same as those of the conventional structure shown in FIGS. 4 to 6 described above, overlapping illustrations and explanations are omitted or simplified except for important parts. The description will focus on the features of

Before describing the specific configuration and operation of the computing unit, first, the method of obtaining physical quantities (axial load, relative displacement in the axial direction) according to this example will be described. In this example, the physical quantity is obtained by dividing it into a size (absolute value) and a direction (direction, sign). First, the method for obtaining the physical quantity will be described.
In the case of this example, the A-phase pulse signal S _A that is the output signal of one sensor 6a of the pair of sensors 6a and 6b (see FIG. 4), each of which is a digitized binary signal, and the other The phase with respect to the B-phase pulse signal S _B which is the output signal of the sensor 6b is set so as to be opposite to each other as shown in FIG. 6A in the neutral state. In other words, these two pulse signals S _A, initial phase difference ratio initial phase difference [delta] ₀ is the phase difference [delta] is the phase difference ratio [delta] / T _A of 180 degrees (neutral state in the neutral state of the S _B [delta] ₀ / T _a is set to 0.5). When the physical quantity changes from this state (when an axial load is applied and a relative displacement in the axial direction occurs), for example, as shown in FIG. 2, the phase difference δ between the two pulse signals S _A and S _B changes. Here, when the exclusive OR of these two pulse signals S _A and S _B is obtained, the signal (XOR signal) S _XOR representing this exclusive OR becomes as shown in the lowermost stage of FIG. As is apparent from FIG. 2, the pulse width T _XOR indicating the time during which the value of the XOR signal S _XOR is L is the magnitude of the change amount of the phase difference δ with respect to the initial phase difference δ ₀ ( = | Δ−δ ₀ |). Then, the such pulse width T _XOR, the ratio of the pulse period T _A of the A-phase pulse signals S _A, the pulse width ratio T _XOR / T _A is a dimensionless quantity that is not affected by the rotational speed Therefore, a value corresponding to the size of the physical quantity to be measured is taken. That is, the pulse width ratio T _XOR / T _A changes according to the magnitude of the physical quantity. Therefore, the relationship between the magnitude of these pulse width ratio T _XOR / T _A and the physical quantity, previously examined in advance by theoretical calculation and experimental, if incorporated in the form of equation or a map or the like on the operation unit, the pulse width It determined the magnitude of the physical quantity based on a ratio T _XOR / T _a.

Next, how to determine the direction (direction) of the physical quantity will be described.
In the case of the rotary machine with a physical quantity measuring device shown in FIG. 4 described above, an inward axial load is applied to the hub 2, so that the hub 2 is relatively displaced axially inward with respect to the outer ring 1. Accordingly, when the scanning position of the detection surface of the encoder 4 by the detectors of the sensors 6a and 6b deviates from the neutral position to the outside in the axial direction, as shown in FIG. With the state as a reference, the phase of the B-phase pulse signal S _B is delayed with respect to the A-phase pulse signal S _A. On the other hand, when an outward axial load acts on the hub 2, the hub 2 is relatively displaced axially outward with respect to the outer ring 1, and accordingly, the scanning position is in a neutral state. As shown in FIG. 3B, the phase of the B-phase pulse signal S _B advances with respect to the A-phase pulse signal S _A with reference to the neutral state. Therefore, if it can be determined whether the phase of the B-phase pulse signal S _B is delayed or advanced with respect to the A-phase pulse signal S _A on the basis of the neutral state, the direction of relative displacement of the hub 2 with respect to the outer ring 1 ( Direction), that is, the direction (direction) of the physical quantity. To perform the judgment, in the case of this example, the out of the pulse edges included in the A-phase pulse signals S _A, the pulse period T _A pair of pulse edges to be used to measure (shown In the example, the value of the B-phase pulse signal S _{B at} the same time as the intermediate pulse edge (falling edge in the illustrated example) sandwiched between a pair of rising edges) ( Use the value of the part with. That is, when this value is L as shown in (A), it is determined that the phase of the B-phase pulse signal S _B is delayed, and when it is H as shown in (B), this It is determined that the phase is advanced.

In the case of the physical quantity measuring device with a rotary machine of the present embodiment, during operation, the range sandwiched between around the phase difference ratio [delta] / T _A 0.5 0 and 1 (0 <[delta] / T _a <1) the are designed so as not to exceed, Stated differently, the range where the phase difference [delta] is sandwiched between 0 ° and 360 ° around the 180 degrees (0 degrees <[delta] It is designed not to exceed <360 degrees). Actually, it is designed not to exceed a narrower range. Therefore, in any case, the maximum value of the pulse width T _XOR during operation is less than half of the pulse period T _A and less than half of the maximum value of the phase difference δ.

Therefore, if the structure of this embodiment, the bit width of the first counter to be used to measure the pulse period T _A, and the bit width of the second counter to be used to measure the pulse width T _XOR is, If the same as one another, under conditions that do not overflow both of these counters during operation, the pulse period T _a than for the clock frequency to be measured (frequency of the first reference clock signal), for measuring the pulse width T _XOR The clock frequency (frequency of the second reference clock signal) can be increased. Specifically, the frequency of the second reference clock signal can be made twice or more the frequency of the first reference clock signal.

Next, the configuration and operation (calculation process of the physical quantity) of the arithmetic unit will be specifically described.
In the case of this example, this computing unit includes a transmitter (not shown), a pair of frequency dividers 8a and 8b, first and second counters 9 and 10, an XOR circuit unit 11, a determination circuit unit 12, And a calculation circuit unit 13.
First, the arithmetic unit, generated by the oscillator, the high frequency original reference clock signal, to generate a by dividing by the frequency divider 8a with dividing ratio N ₁ first reference clock signal, dividing A second reference clock signal is generated by frequency division by a frequency division ratio N ₂ (≠ N ₁ ) by the device 8b.
In the case of this example, both the frequency division ratios N ₁ and N ₂ do not change during operation. Accordingly, the frequencies of the first and second reference clock signals do not change.
Such frequency division ratios N ₁ and N ₂ are regulated to appropriate values in advance. Specifically, the counters 9 and 10 (a pair of counters having the same bit width) do not overflow even at the lowest rotational speed in the rotational speed range in which the physical quantity is to be measured. The frequency division ratios N ₁ and N ₂ are regulated so that the frequencies of the first and second reference clock signals can be made as large as possible. In particular, in the case of this example, in consideration of the above-described circumstances, the frequency of the second reference clock signal is set to be twice or more the frequency of the first reference clock signal.

The arithmetic unit inputs the A-phase pulse signal S _A and the B-phase pulse signal S _B to the XOR circuit unit 11, and is an exclusive OR between these signals S _A and S _B. , XOR signal S _XOR is output.

The computing unit measures the pulse period T _A of the A-phase pulse signal S _A with a measuring unit including the first counter 9. Specifically, simultaneously with detecting the rising edge of the A-phase pulse signal S _A , the first counter 9 starts counting the number of pulses of the first reference clock signal, and the A-phase pulse signal S _A At the same time as the next rising edge is detected, the counting is finished. The pulse period T _A is measured by reading the count value at this time. At the same time reads the count value, by clearing the count value of the first counter 9, sequentially measures the pulse period T _A.

In addition, the measuring section including the second counter 10 measures the pulse width T _XOR of the XOR signal S _XOR . Specifically, simultaneously with the detection of the falling edge of the XOR signal S _XOR , the second counter 10 starts counting the number of pulses of the second reference clock signal, and detects the rising edge of the XOR signal S _XOR. At the same time, the count ends. The pulse width T _XOR is measured by reading the count value at this time. Then, simultaneously with reading this count value, the pulse width T _XOR is sequentially measured by clearing the count value of the second counter 10.

In addition, the computing unit determines whether the phase of the B-phase pulse signal S _B is delayed or advanced with respect to the A-phase pulse signal S _{A by the} determination circuit unit 12. This determination is performed based on the principle described above (described with reference to FIG. 3). That is, based on whether the value of the B-phase pulse signal S _B is L or H at the same time as the intermediate pulse edge (falling edge) of the A-phase pulse signal S _A , the phase is Judge whether it is late or advanced.

The computing unit calculates the physical quantity to be measured by the calculation circuit unit 13. Specifically, performs a calculation for obtaining a pulse width ratio T _XOR / T _A which is the ratio of the pulse width T _XOR and the pulse period T _A measured as described above, the pulse width ratio T _XOR obtained in this manner / T with determining the magnitude of the physical quantity based on _a, performs computation for obtaining the direction of the physical quantity (direction) based on a determination result of the determination circuit 12.

  According to the rotating machine with a physical quantity measuring device of the present example configured as described above, the counter for measuring the measured quantity related to the pulse signal necessary for calculating the physical quantity is set so that the counter does not overflow during operation. In the case of the conventional structure described above, the resolution of the measured quantity (the resolution of the physical quantity) in the entire rotational speed range in which the physical quantity is to be measured, including a high rotational speed, without increasing the bit width of It can be improved compared to Hereinafter, this reason will be described.

In the case of the rotating machine with a physical quantity measuring device of this example, instead of calculating the physical quantity based on the phase difference ratio (phase difference δ / pulse period T _A ) as in the conventional structure described above, the pulse width ratio ( The physical quantity is calculated based on the pulse width T _XOR / pulse period T _A ). Here, when the same rotational speed of the hub 2, with the pulse width ratio T _XOR / T _A and the phase difference ratio [delta] / T _A, the pulse period T _A is each denominator, mutually identical Although the (same duration), varying in accordance with said physical quantity, the maximum value of the pulse width T _XOR is a molecule of the pulse width ratio T _XOR / T _a is a molecule of the phase difference ratio [delta] / T _a It becomes less than half of the maximum value of a certain phase difference δ (time width is shortened). Therefore, if the bit width of the second counter 10 for measuring the pulse width T _XOR and the bit width of the counter for measuring the phase difference δ are the same, both of these values are required during operation. The reference clock frequency (frequency of the second reference clock signal) for measuring the pulse width T _XOR is more than twice as high as the reference clock frequency for measuring the phase difference δ under the condition that the counter does not overflow. I can do it. On the other hand, the amount of change in the pulse width T _XOR (time width) and the amount of change in the phase difference δ (time width) accompanying the change in the physical quantity are equal to each other. Therefore, the count value corresponding to the change amount of the pulse width T _XOR can be made larger than the count value corresponding to the change amount of the phase difference δ.
As a result, in the case of this example, the measured amount related to the pulse signal necessary for calculating the physical quantity (in the case of the present example, the pulse width T _XOR , in the case of the conventional structure described above, the phase difference δ ) For measuring the total rotation including a high rotational speed without increasing the bit width of the counter on the condition that the counter (in this case, the second counter 10 in this example) does not overflow during operation. In the speed range, the resolution of the measured quantity (resolution of the physical quantity) can be improved as compared with the conventional structure described above.

In the case of this example, the count value corresponding to the amount of change in the measured amount can be made larger than in the case of the conventional structure described above. For this reason, a measurement error (measurement error of the physical quantity) of the change amount of the measured quantity due to variations in the generation timing of the pulse edges included in both the A-phase and B-phase pulse signals S _A and S _B is suppressed. Therefore, the measurement accuracy of the change amount of the measurement target (the measurement accuracy of the physical quantity) can be improved as compared with the above-described conventional structure.

In the embodiment described above, the present invention is applied to the conventional structure shown in FIGS. However, the present invention is not limited to this, and can be applied to various rotating machines with physical quantity measuring devices that satisfy the requirements described in the claims. For example, the present invention can be applied not only to a structure that uses a rolling bearing unit for supporting a wheel of an automobile as a rotating machine, but also to a structure that uses a spindle device of a machine tool or a transmission of an automobile. Further, the present invention is not limited to a structure that measures displacement or load in the axial direction, but can be applied to a structure that measures displacement or load in the radial direction.
Further, in the embodiment described above, and the denominator of the pulse width ratio T _XOR / T _A, the pulse period T _A, and the time interval between the rising edge of the A-phase pulse signal S _A (see FIGS. 2-3) . However, when the present invention is implemented, the pulse period T _A can be replaced with the time width between the falling edges of the A-phase pulse signal S _A instead.
When the present invention is implemented, the computing unit may be installed in a state of being attached to a part of the rotating machine, or a place away from the rotating machine (for example, the rotating machine is a rolling bearing unit for supporting the wheel. In this case, it may be installed on a part of the vehicle body.

DESCRIPTION OF SYMBOLS 1 Outer ring 2 Hub 3 Rolling element 4 Encoder 5 Cover 6a, 6b Sensor 7 Through-hole 8a, 8b Frequency divider 9 First counter 10 Second counter 11 XOR circuit part 12 Judgment circuit part 13 Calculation circuit part

Claims (1)

A stationary member that does not rotate when in use, a rotating member that is rotatably supported by the stationary member by a plurality of rolling bearings, and a detection surface that is fixed to the rotating member and concentric with the rotating member An encoder in which the characteristics of the detected surface are alternately changed with respect to the circumferential direction, and supported by the stationary member in a state where the respective detection units are opposed to the detected surface. A pair of sensors that generate as output signals a pulse signal corresponding to a change in characteristics of the part facing the detection unit, and using the output signals of both sensors, the displacement of the rotating member relative to the stationary member; A rotating machine with a physical quantity measuring device comprising an arithmetic unit for obtaining a physical quantity of at least one of a load acting between the stationary member and the rotating member,
In the neutral state where the stationary member and the rotating member are not relatively displaced, the initial phase difference between the output signals of the two sensors is set to 180 degrees,
The computing unit calculates an exclusive OR between the output signals of the two sensors, and is a ratio between the pulse width of the signal representing the exclusive OR and the pulse period of the output signals of both the sensors. The physical quantity is calculated based on a pulse width ratio, and the reference clock frequency for measuring the pulse width is set higher than the reference clock frequency for measuring the pulse period. It is characterized by measuring width and pulse period .
Rotating machine with physical quantity measuring device.

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