JP2023131736A - Channel switch valve - Google Patents

Abstract

To enable calibration of a valve body rotation range in a rotation drive portion, while suppressing increase of cost.SOLUTION: A channel switch valve 10 includes: a valve body 14 that is formed with a valve chamber 12 inside, and is formed with gateways 24, 26, and 28 of fluid on a wall surface forming the valve chamber 12; a valve body 16 that has a valve shaft, is rotatably disposed in the valve chamber 12, and is formed with a channel; a sealing portion 38 that is provided so as to surround a periphery of an opening portion of the channel in the valve body 16, and seals a space between the gateways and the valve body 16 while the opening portion and the gateways oppose to each other; and a rotation drive portion that rotates the valve body 16 via the valve shaft so as to selectively switch a communication state of the plurality of gateways through the channel of the valve body 16, and can detect an angle position of the valve body 16. Stoppers 44 and 46 are provided inside the valve body 14, which regulate further rotations of the valve body 16 on at least one of an upper limit and a lower limit of a valve body rotation range.SELECTED DRAWING: Figure 7

Description

The present invention relates to a flow path switching valve, and more particularly, to a flow path switching valve that switches a flow path by rotating and sliding a valve body within a valve chamber.

2. Description of the Related Art A flow path switching valve is known that switches a flow path by rotating a cylindrical or ball-shaped valve body (for example, see Patent Document 1).

In this type of flow path switching valve, a valve body is rotationally driven using a rotational drive unit consisting of a motor, a drive gear, and the like.

Japanese Patent Application Publication No. 2018-115691

In the flow path switching valve as described above, calibration is appropriately performed to set the upper and lower limits of the valve body rotation range by the motor. It is conceivable to use an absolute angle sensor such as a rotary potentiometer for this calibration. However, if an absolute angle sensor is used, it is thought that the product price will increase due to increased cost.

An object of the present invention is to enable calibration of a valve body rotation range while suppressing an increase in cost.

A flow path switching valve according to a first aspect includes a valve body having a valve chamber formed therein and a fluid inlet and outlet formed in a wall surface forming the valve chamber, and a valve shaft, A valve body is rotatably arranged in a room and has a flow path formed therein, and the valve body is provided so as to surround the opening of the flow path, and the opening and the inlet/outlet are opposed to each other. a sealing portion that seals between the inlet and outlet and the valve body, and a sealing portion that seals between the inlet and the outlet through the valve shaft so that the communication state of the plurality of inlets and outlets is selectively switched through the flow path of the valve body. a rotation drive unit capable of rotating the valve body and detecting the angular position of the valve body, and a stopper that limits further rotation of the valve body at at least one of an upper limit and a lower limit of a valve body rotation range; is provided inside the valve body.

In this flow path switching valve, the flow path of the valve body can be switched by rotating the valve body via the valve shaft using the rotation drive unit. Further, in this flow path switching valve, further rotation of the valve body can be restricted at at least one of the upper and lower limits of the valve body rotation range by the stopper provided inside the valve body. Since the rotation drive unit can detect the angular position of the valve body, it detects the position where the rotation of the valve body is stopped by the stopper as the upper or lower limit of the valve body rotation range, and performs calibration of the valve body rotation range. It can be carried out. If the angular difference between the upper limit and the lower limit is known, the lower limit can be determined from the detected upper limit, and the upper limit can be similarly determined from the lower limit. Therefore, compared to the case where an absolute angle sensor is used for calibration, it is possible to calibrate the valve body rotation range in the rotation drive unit while suppressing an increase in cost.

In a second aspect, in the flow path switching valve according to the first aspect, the valve body has a part that protrudes outward in the radial direction of the valve body, and the stopper is provided at at least one of an upper limit and a lower limit of the rotation range of the valve body. An abutting protrusion is provided.

This flow path switching valve has a simple configuration in which a protrusion provided on the valve body contacts a stopper at at least one of the upper and lower limits of the valve body rotation range, allowing for calibration of the valve body rotation range at a lower cost. It can be performed.

In a third aspect, in the flow path switching valve according to the first aspect or the second aspect, the stopper is provided at both an upper limit and a lower limit of the valve body rotation range.

In this flow path switching valve, stoppers are provided at both the upper and lower limits of the valve body rotation range, so even if the angular difference between the upper and lower limits is not known, the valve body can rotate by detecting the upper and lower limits. Range calibration can be performed.

According to the flow path switching valve according to the present invention, it is possible to calibrate the valve body rotation range in the rotation drive unit while suppressing an increase in cost.

FIG. 2 is a perspective view showing a flow path switching valve according to the present embodiment. FIG. 3 is a bottom view showing the flow path switching valve according to the present embodiment. 3 is a sectional view taken along arrow 3-3 in FIG. 2. FIG. FIG. 2 is an exploded perspective view showing a flow path switching valve according to the present embodiment. It is a perspective view showing a valve body. FIG. 3 is an exploded perspective view showing the valve body and the holder member that are turned upside down. FIG. 7 is a cross-sectional view showing a state in which a protrusion of the valve body is in contact with a stopper that defines the lower limit of the rotation range of the valve body. FIG. 7 is a cross-sectional view showing a state in which a protruding portion of the valve body is in contact with a stopper that determines the upper limit of the rotation range of the valve body. 8 is a cross-sectional view showing the state of the valve body corresponding to FIG. 7. FIG. 8 is a longitudinal sectional view showing the state of the valve body corresponding to FIG. 7. FIG.

A flow path switching valve 10 according to one embodiment of the present invention will be described using FIGS. 1 to 3. In each figure, gaps formed between members, separation distances between members, etc. may be exaggerated in order to facilitate understanding of the invention and for convenience in drawing. be. Further, in this specification, descriptions expressing positions and directions such as up and down, right and left, front and rear, etc. are based on the direction arrow display in FIG. 1, and do not refer to positions and directions in actual use. In Figure 1, "UP" is upward (top), "DOWN" is downward (lower), "LH" is left (left), "RH" is right (right), and "FR" is forward. The direction (front side) and "RR" indicate the rear direction (rear side). Note that these directions are for convenience and may differ from the directions when installed in a vehicle or the like.

(Configuration of flow path switching valve)
FIG. 1 is a perspective view showing the overall configuration of a flow path switching valve 10 according to an embodiment of the present invention. FIG. 2 is a plan view showing the flow path switching valve 10. FIG. 3 is a sectional view taken along arrow 3-3 in FIG.

The flow path switching valve 10 is used, for example, as a rotary-type four-way valve that switches the flow path of fluid flowing in the engine room of an automobile. The flow path switching valve 10 includes a valve body 14 , a valve body 16 , a sealing portion 38 , and a rotation drive portion 18 .

(valve body)
In FIG. 2, the valve body 14 is composed of a base member 20 and a holder member 21 made of, for example, synthetic resin. The base member 20 has an opening on the lower side, and a holder member 21 is fitted and fixed in the opening portion. The space between the base member 20 and the holder member 21 is sealed by, for example, an O-ring 54. As shown in FIGS. 6 and 9, a cylindrical valve chamber 12, for example, is formed inside the valve body 14. Fluid inlets and outlets 24, 26, and 28 are formed in the wall surface of the valve chamber 12. The inlets and outlets 24 and 26 are open to the valve chamber 12 so as to face each other. The entrance/exit 28 opens in a direction perpendicular to the direction connecting the entrances/exits 24 and 26 in a horizontal plane.

In FIGS. 1 and 2, ports 24A, 26A, and 28A serving as pipe joints communicating with inlets and outlets 24, 26, and 28 are integrally provided on the outer surface of a base member 20 in the valve body 14. Further, a plurality of mounting portions 32 are provided on the outer surface of the base member 20 for mounting the flow path switching valve 10 in the engine room of an automobile or the like. In FIG. 6, the holder member 21 is integrally provided with an inlet/outlet 29 to the valve chamber 12 and a port 29A serving as a pipe joint communicating with the inlet/outlet 29.

In FIGS. 3 and 6, the fitting portion between the holder member 21 and the base member 20 is sealed airtightly or watertightly, for example, by an O-ring 54, for example. The O-ring 54 is attached, for example, to a groove 56 provided in the holder member 21.

Note that in this embodiment, the holder member 21 and the base member 20 are coupled with the screws 25 with the O-ring 54 in between, but the holder member 21 and the base member 20 may be coupled by welding. In the case of employing a structure that also ensures sealing performance by welding, the O-ring 54 is not necessary.

The holder member 21 has a flange 21A, and four through holes 21B are formed in the flange 21A. For example, a screw 25 is passed through the through hole 21B. A screw hole 20B into which a screw 25 is screwed is formed in an end surface 20A of the base member 20 that the flange 21A contacts. The holder member 21 is fastened and fixed to the base member 20 by screws 25 .

Moreover, two through holes 21C are formed in the flange 21A, for example. A pin 52 (FIG. 6) for positioning is inserted through this through hole 21C. A hole 20C into which the pin 52 fits is formed in the end surface 20A of the base member 20. The pin 52 is a jig used when assembling the holder member 21 to the base member 20. By inserting the pin 52 inserted into the through hole 21C of the flange 21A into the hole 20C of the base member 20, the center of the valve chamber 12 of the base member 20 and the center of the holder member 21 can be positioned. This is because the lower end portion of the valve body 16 rotating within the valve chamber 12 is rotatably supported by the inner circumferential surface 21E of the holder member 21, as will be described later.

Further, the flange 21A is provided with, for example, two protrusions 21D that protrude toward the valve body 14 side. A hole 20D is formed in the end surface 20A of the base member 20, and the hole 20D fits into the projection 21D. By fitting the protrusion 21D and the hole 20D, it is possible to suppress changes in alignment over time between the center of the valve chamber 12 of the base member 20 and the center of the holder member 21.

As shown in FIG. 3, the upper wall surface of the valve chamber 12 is provided with a fitting hole 30 into which the valve shaft 48 of the valve body 16 is rotatably inserted. Further, the base member 20 is, for example, integrally provided with a support portion 15 extending on the side opposite to the port 28A. The rotation drive unit 18 is fixed onto the base member 20 and the support unit 15 using, for example, screws 22.

(valve body)
In FIGS. 3 to 5, the valve body 16 is a member made of, for example, synthetic resin, and is arranged rotatably within the valve chamber 12 about an axis O1 extending in the vertical direction. The upper part of the valve body 16 is pivotally supported in a fitting hole 30 provided in the upper wall surface of the valve chamber 12 via an O-ring 34. The O-ring 34 is attached, for example, to a groove 16A1 formed in the upper outer peripheral surface of the valve body 16. On the other hand, the lower part of the valve body 16 is pivotally supported on the inner circumferential surface 21E of the holder member 21 via an O-ring 35 (see also FIG. 10). The O-ring 35 is attached, for example, to a groove 16B1 formed in the lower outer peripheral surface 16B of the valve body 16.

The valve body 16 has a substantially cylindrical outer peripheral surface 16C centered on the axis O1. The outer peripheral surface 16C is provided in a range of approximately 180°. In other words, the outer peripheral surface 16C is formed into a substantially semicircular shape when viewed from the direction of the axis O1. The radius of curvature of the outer peripheral surface 16C is set to be slightly smaller than the radius of the valve chamber 12. A gap S1 is formed between a cylindrical inner wall 12A of the wall surface of the valve chamber 12 and an outer peripheral surface 16C of the valve body 16 (FIGS. 7 and 8). This gap S1 is also formed between the tip of a protrusion 16G, which will be described later, and an inner wall 12A of the valve chamber 12. Note that the size of the gap S1 may vary depending on the location.

In order to selectively communicate the inlets and outlets 24, 26, 28, and 29 provided in the valve body 14, in other words, to selectively switch the communication state of the inlets and outlets 24, 26, 28, and 29, the valve body 16 is A flow path (internal flow path) 36 is provided inside. Specifically, the valve body 16 has openings 36A and 36B formed in a direction perpendicular to the direction of the rotation axis O1 of the valve body 16. As shown in FIG. 9, the openings 36A and 36B are orthogonal to each other. Further, the valve body 16 has an opening 36C formed below the rotation axis O1. The openings 36A, 36B, and 36C communicate with the flow path 36.

Annular recesses 16D are formed around the openings 36A and 36B on the outer circumferential surface 16C of the valve body 16, respectively, to which seat members 40 and 42, which will be described later, are attached. Projections 16E for positioning the sheet members 40, 42 are provided at, for example, two or one location inside the annular recess 16D around the openings 36A, 36B.

A valve shaft 48 is integrally provided on the upper part of the valve body 16. The central axis of the valve shaft 48 is coaxial with the axis O1 of the valve body 16. The valve shaft 48 is provided with a gear portion 48A having irregularities in the circumferential direction, and this gear portion 48A engages with the output portion of the rotary drive portion 18. Between the upper outer circumferential surface 16A and the outer circumferential surface 16C of the valve body 16, a medium diameter portion 16F is provided which has a larger diameter than the upper outer circumferential surface 16A and a smaller diameter than the outer circumferential surface 16C. A gap S2 is formed between the medium diameter portion 16F and protrusions forming stoppers 44 and 46, which will be described later. By forming this gap S2 and the above-described gap S1, retention of foreign matter in the valve chamber 12 is suppressed.

(Sealing part)
4 and 9, the sealing part 38 is provided so as to surround the openings 36A, 36B of the flow path 36 in the valve body 16, and the openings 36A, 36B and the inlet/outlets 24, 26, 28 are opposed to each other. It is a member that seals between the inlet/outlet 24, 26, 28 and the valve body 16 in the open state, and includes, for example, a seat member 40 and an O-ring 42. The seat member 40 and the O-ring 42 are arranged in the two annular recesses 16D of the valve body 16, respectively. The sheet member 40 is made of synthetic resin, for example, and is formed in an annular shape with openings corresponding to the openings 36A and 36B of the flow path 36 in the valve body 16. The inner diameter of the sheet member 40 is set to be equal to the inner diameter of the inlet/outlet 24, 26, 28, for example.

The surface of the seat member 40 that slides on the inner wall 12A of the valve chamber 12 is configured as a cylindrical surface along the inner wall 12A. Thereby, the valve body 16 can smoothly rotate and slide within the valve chamber 12 with the seat member 40 in contact with the inner wall 12A of the valve chamber 12, and the openings 36A, 36B and the inlet/outlet 24, 26 , 28 facing each other, the space between the inlet/outlet 24, 26, 28 and the valve body 16 can be sealed. On the other hand, the back surface of the sheet member 40 is, for example, substantially flat. A recess 40A that fits into the projection 16E of the valve body 16 is formed on the back surface. The O-ring 42 is arranged at the bottom of the annular recess 16D, and the sheet member 40 is fitted onto the O-ring 42 from above. That is, the space between the seat member 40 and the valve body 16 is sealed, for example, airtightly or watertightly by the O-ring 42.

As an example, a resin with low water absorption such as PPS (polyphenylene sulfide) is used for the valve body 14 and the valve body 16, a self-lubricating resin such as PTFE (fluororesin) is used for the seat member 40, and the O-ring 42 Synthetic rubber can be used.

(Rotation drive part)
In FIGS. 1 to 3, the rotary drive unit 18 is rotated through a valve shaft 48 so that the communication state of the plurality of inlets and outlets 24, 26, 28, and 29 is selectively switched through the flow path 36 of the valve body 16. It is possible to rotate the valve body 16 and to detect the angular position of the valve body 16. The rotation drive unit 18 includes a motor, a drive gear, etc. for rotating the valve shaft 48, and rotates the valve body 16 via the valve shaft 48 around the rotation axis (center line) O1. is placed above. The valve shaft 48 of the valve body 16 engages with the rotation drive unit 18 around the axis O1. The rotation drive unit 18 is provided with a connector 50 to which wiring for communication with the control unit and power supply is connected, for example. The motor may be a stepping motor or may be a combination of a motor such as a DC motor and a magnetic sensor (for example, a Hall element) so that the angular position of the valve body 16 can be detected.

In FIGS. 6, 7, and 8, the valve body 16 is rotatably driven within a predetermined valve body rotation range. Stoppers 44 and 46 for restricting further rotation of the valve body 16 are provided inside the valve body 14 at at least one, for example, both of the upper and lower limits of this valve body rotation range. Specifically, the stoppers 44 and 46 are integrally provided around the insertion hole 30 (FIG. 2) on the upper wall surface of the valve chamber 12. Stop 44 defines the upper limit and stop 46 defines the lower limit. The lower limit of the upper limit can also be expressed as one end and the other end. Further, by providing the stoppers 44 and 46 inside the valve body 14, that is, on the upper wall surface of the valve chamber 12, the valve body 16 can be placed from the lower side of the valve chamber 12.

The valve body 16 has a protruding portion that protrudes radially outward from, for example, the middle diameter portion 16F of the valve body 16 and abuts against the stoppers 44 and 46 at at least one of the upper and lower limits of the valve body rotation range (in this embodiment, both). 16G is provided. The protruding portion 16G is, for example, a fan-shaped convex portion when viewed from above, and is provided at one location. This protrusion 16G contacts the stopper 44 at the upper limit of the valve body rotation range, and contacts the stopper 46 at the lower limit. The arrangement of the stoppers 44 and 46 and the size of the protruding portion 16G in the circumferential direction of the valve body 16 are changed as appropriate depending on the valve body rotation range. In other words, the positions of the stoppers 44 and 46 are determined in consideration of this angular difference and the shape of the protrusion 16G of the valve body 16.

Note that the angular difference θ between the upper and lower limits of the valve body rotation range in this embodiment is 270° (FIG. 7). In this way, when the angular difference between the upper and lower limits of the valve body rotation range is known, the lower limit can be calculated from the upper limit, and the upper limit can be calculated from the lower limit, using a calibration program. Therefore, only one of the upper limit stopper 44 and the lower limit stopper 46 may be provided. Further, a protrusion that abuts the upper limit stopper 44 and a protrusion that abuts the lower limit stopper 46 may be provided separately.

(action, effect)
Next, the functions and effects of the flow path switching valve 10 of this embodiment will be explained. 1 and 3, in this embodiment, the flow path 36 of the valve body 14 can be switched by rotating the valve body 16 via the valve shaft 48 by a rotary drive unit 18 consisting of a motor, a drive gear, etc. can. Specifically, the communication state of the inlets and outlets 24, 26, 28, and 29 provided in the valve body 14 can be selectively switched through the flow path 36 of the valve body 16.

For example, in FIGS. 9 and 10, the valve body 16 is at the lower limit of the valve body rotation range, the inlets and outlets 26 and 29 are in communication, and the inlets and outlets 24 and 28 are in communication. In addition, when the valve body 16 is rotated 90° clockwise from the state shown in FIG. 9, the inlets and outlets 26, 28, and 29 are brought into communication, and the inlet and outlet 24 is closed. Further, when the valve body 16 is rotated 90 degrees clockwise, the inlets and outlets 24, 28, and 29 communicate with each other, and the inlet and outlet 26 is closed. When the valve body 16 is further rotated clockwise to the upper limit of the valve body rotation range, the inlets and outlets 24 and 29 are in communication with each other, and the inlets and outlets 26 and 28 are in communication with each other.

Further, in this embodiment, the stoppers 44 and 46 provided on the outside of the valve body 14 can restrict further rotation of the valve body 16 at both the upper and lower limits of the valve body rotation range. Specifically, the protruding portion 16G of the valve body 16 comes into contact with the stoppers 44 and 46, respectively, thereby restricting further rotation of the valve body 16.

Since the rotation drive unit 18 is capable of detecting the angular position of the valve body 16, the protrusion 16G detects the position where the rotation of the valve body 16 is stopped by the stoppers 44 and 46 as the upper limit or lower limit of the valve body rotation range. The valve body rotation range can be calibrated. It is desirable that the calibration be performed irregularly or regularly, such as each time the flow path switching valve 10 is used or once a month. Here, an example of a calibration procedure using the protrusion 16G of the valve body 16 and the stoppers 44, 46 will be described with reference to FIGS. 7 and 8.

When the valve body 16 is rotated counterclockwise by the rotary drive unit 18 (FIG. 1) from a point where the valve body 16 is between the upper and lower limits of the valve body rotation range, the protrusion 16G moves to the lower limit stopper in FIG. 46, further rotation of the valve body 16 is restricted. At this time, by detecting the stop of the motor of the rotation drive unit 18, it is possible to detect that the valve body 16 has reached the lower limit of the valve body rotation range. Next, when the valve body 16 is rotated clockwise by the rotation drive unit 18 (FIG. 1), the protrusion 16G contacts the upper limit stopper 44 in FIG. 8, and further rotation of the valve body 16 is restricted. At this time, by detecting that the motor of the rotation drive unit 18 has stopped, it is possible to detect that the valve body 16 has reached the upper limit of the valve body rotation range.

Note that the rotational position of the motor of the rotation drive unit 18 may be detected using a sensor such as a Hall element, or may be detected from the back electromotive force of a stepping motor or a brushless motor. The rotation speed of the motor (that is, the angular position of the valve body) after the protrusion 16G is in contact with the lower limit stopper 46 or the upper limit stopper 44 can be detected using a sensor, but in the case of a stepping motor, the input pulse The rotational speed of the motor (that is, the angular position of the valve body) may be detected from the number. The state in which the protruding portion 16G is in contact with the lower limit stopper 46 or the upper limit stopper 44 (reference position, motor stopped state) can also be detected from a sensor or a back electromotive force.

As a result, the angular position of the valve body 16 in the rotation drive unit 18 at the upper limit of the valve body rotation range is associated with the angular position of the valve body 16 in the rotation drive unit 18 at the lower limit of the valve body rotation range, so that Calibration of the valve body rotation range is completed. Thereby, the angular position of the valve body 16 can be changed arbitrarily within the valve body rotation range.

In this embodiment, the stoppers 44 and 46 are provided at both the upper and lower limits of the valve body rotation range, so even if the angular difference between the upper and lower limits is not known, the valve body can be rotated by detecting the upper and lower limits. The rotation range can be calibrated. If the angular difference between the upper and lower limits of the valve body rotation range is known, the lower limit can be calculated from the upper limit and the upper limit can be calculated from the lower limit using a calibration program. Therefore, even in a configuration in which either the upper limit stopper 44 or the lower limit stopper 46 is provided, calibration can be performed.

As described above, in this embodiment, the simple configuration in which the protrusion 16G provided on the valve body 16 comes into contact with the stoppers 44 and 46 at least at one of the upper limit and the lower limit of the valve body rotation range makes it possible to ensure absolute calibration. Compared to the case where an angle sensor is used, it is possible to calibrate the valve body rotation range in the rotation drive unit 18 while suppressing an increase in cost.

[Other embodiments]
Although one embodiment of the present invention has been described above, the present invention is not limited to the above, and it is of course possible to implement various modifications other than the above without departing from the spirit thereof. It is.

It goes without saying that the number and arrangement of inlets and outlets formed in the valve body 14 can be changed as appropriate depending on the application location of the flow path switching valve 10 and the like. In the above embodiment, a four-way valve is used as an example of the flow path switching valve 10, but it goes without saying that it may also be a two-way valve or a three-way valve, for example.

Furthermore, the flow path switching valve 10 of the above embodiment is assumed to be used for flow path switching in the engine compartment of a vehicle (engine cooling circuit, electronic device cooling circuit, etc.); Of course, the present invention is not limited to this, and may be used, for example, for switching channels in hot water supply equipment.

Although the valve body 16 is provided with the protruding portion 16G that comes into contact with the stoppers 44 and 46, the present invention is not limited to this. Any configuration may be used as long as the rotation above can be restricted.

10 Flow path switching valve 12 Valve chamber 12A Inner wall (wall surface)
14 Valve body 16 Valve body 16G Projection part 18 Rotation drive part 24 Inlet/outlet 26 Inlet/outlet 28 Inlet/outlet 29 Inlet/outlet 36 Flow path 36A Opening 36B Opening 36C Opening 38 Sealing part 44 Stopper 46 Stopper 48 Valve shaft

Claims (3)

a valve body having a valve chamber formed therein and a fluid inlet/outlet formed on a wall surface forming the valve chamber;
a valve body having a valve shaft, rotatably disposed within the valve chamber, and having a flow path formed therein;
a sealing part that is provided to surround the opening of the flow path in the valve body, and seals between the inlet and the outlet with the opening and the inlet and the outlet facing each other;
The valve body is rotated via the valve shaft so that the communication state of the plurality of input and output ports is selectively switched through the flow path of the valve body, and the angular position of the valve body can be detected. A drive unit;
Equipped with
A flow path switching valve, wherein a stopper for restricting further rotation of the valve body at at least one of an upper limit and a lower limit of a valve body rotation range is provided inside the valve body. The flow path according to claim 1, wherein the valve body is provided with a protrusion that protrudes radially outward of the valve body and comes into contact with the stopper at at least one of an upper limit and a lower limit of the valve body rotation range. switching valve. The flow path switching valve according to claim 1 or 2, wherein the stopper is provided at both an upper limit and a lower limit of the valve body rotation range.