Actuator

Abstract

To provide a compact actuator having a simple structure.SOLUTION: An actuator A comprises a motor M comprising a stator M2 and a rotor M1, at least one cylinder S arranged adjacent to the motor M, and a piston P mounted on a driving shaft 3 and arranged inside the cylinder S. The rotor M1 is formed in a hollow structure. The driving shaft 3 is stored inside the rotor M1 so that a portion of the driving shaft 3 and a portion of the rotor M1 are screwed with each other while making shaft centers X match with each other. The driving shaft 3 reciprocates along the shaft center X, accompanying rotation of the rotor M1.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to an actuator that includes a cylinder containing a piston and a motor, and that reciprocates the piston by rotational driving of the motor. [Background technology]

[0002] Conventionally, such an actuator has been disclosed in, for example, Patent Document 1 (see

[0011] to

[0015] ,

[0026] FIG. 1).

[0003] This actuator also relates to an air suspension device for a vehicle. This device is equipped with a cylinder 5 that communicates with a pair of air springs 2, and the inside of the cylinder 5 is divided into two chambers R1 and R2 by a piston 6. The volume of the air spring 2 changes by displacing the piston 6. The driving source is a motor 7a, and the rotational motion of the motor 7a is transmitted to the piston 6 via a motion conversion mechanism 7b.

[0004] This actuator does not adjust the vehicle height by supplying or discharging compressed air from an external source, but controls the vehicle body posture by displacing the piston 6 of the cylinder 5 connected to each air spring 2. Therefore, it is not easily affected by the compressibility of the air when supplying or discharging the compressed air.

[0005] In addition, there is little energy loss because no compressor is used and the compressed air is not released into the atmosphere from the air springs 2. Moreover, for example, the pressure of the left and right air springs 2 can be adjusted simultaneously, enabling highly responsive vehicle body posture control.

[0006] Furthermore, since there is no need to install a large-capacity compressor, and no need to supply or exhaust large volumes of compressed air to the air spring 2, the air suspension device does not become larger, and there is no risk of it becoming difficult to install it on a vehicle. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2009-298170 A Summary of the Invention [Problem to be solved by the invention]

[0008] In the above conventional actuator, the rotational motion of the motor 7a is converted into the linear motion of the piston 6 via the motion conversion mechanism 7b. As the motion conversion mechanism 7b, for example, a combination of a screw shaft provided on the outer periphery of one end of the rod 6a and a nut connected to the motor 7a so as to screw into the screw shaft, or a combination of a rack formed on one end of the rod 6a and a worm gear meshing with the rack and connected to the motor 7a, etc., is used.

[0009] However, in both of these configurations, another gear or the like is connected to the motor 7a, and the rotational drive of this gear is further transmitted to the rod 6a of the piston 6. Therefore, a certain space is required for arranging these members. Also, in order to ensure meshing transmission between the rotating shaft of the motor 7a and the rod 6a, accurate positioning of both is required, which increases the load on the structural design of the connection and the machining of the members.

[0010] As described above, conventional actuators have various issues to be resolved, particularly with regard to the mechanism for converting the rotational drive of the motor into linear drive of the piston, and there has been a demand for a compact actuator with a simple configuration. [Means for solving the problem]

[0011] (Features) The actuator according to the present invention has the following characteristic configuration: a motor having a stator and a rotor; At least one cylinder disposed adjacent to the motor; a piston attached to a drive shaft and provided inside the cylinder; the rotor has a hollow structure, and the drive shaft is accommodated inside the rotor in a state in which a part of the drive shaft and a part of the rotor are screwed together while their axial centers are aligned, The drive shaft is configured to reciprocate along the axis as the rotor rotates.

[0012] (effect) In the actuator of this configuration, the drive shaft penetrates the inside of the hollow rotor, and the two are configured to overlap along the direction of the axis. Generally, a mechanism with a piston requires a space for the drive shaft that reciprocates the piston in addition to the arrangement space for the cylinder that contains the piston, and therefore a device housing of a certain size is required. However, with this configuration, the internal space of the rotor can be used as part of the reciprocating space of the drive shaft, making it possible to make the device size more compact.

[0013] In addition, a part of the drive shaft and a part of the rotor are screwed together with their axes aligned. This allows the rotor to function as a member that converts its own rotational drive into reciprocating motion of the drive shaft. Moreover, compared to a typical drive transmission mechanism in which the output shaft of the motor and the drive shaft of the piston, which are arranged in series or parallel, are connected using a separate gear or the like, the length and width of the mechanism are significantly reduced. This makes it possible to obtain a compact actuator.

[0014] (Features) It is advantageous for the actuator according to the present invention to have two spaces defined by the cylinder and the piston.

[0015] (effect) The configuration in which two spaces are provided includes, for example, a configuration in which two sets of a cylinder and a piston are provided to form one space, and a configuration in which the internal space of one cylinder is divided into two by one piston, but in either case, there is only one motor.

[0016] Therefore, with these configurations, one motor can reciprocate one or two drive shafts along the axis to alternately expand or contract two spaces with different phases, thereby improving the usability of the actuator of this configuration for drive mechanisms that utilize a pair of pressure increases and decreases.

[0017] (Features) In the actuator of the present invention, it is preferable that a single cylinder is provided as the cylinder, and that the piston is arranged in a state in which it divides the inside of the cylinder into a first chamber and a second chamber, and that a male threaded portion formed on a part of the drive shaft and a female threaded portion formed on a part of the inner surface of the rotor are screwed together, and that the female threaded portion is provided at one of both ends of the rotor along the axis that is farther from the cylinder.

[0018] (effect) In an actuator with a single cylinder like this configuration, the drive shaft is attached to the piston, and the piston often reciprocates with the vicinity of the center of the cylinder as a reference. In this case, since the male thread reciprocates relative to the female thread, it is preferable that the female thread is located at the center of the male thread when the piston is in the reference position. The female thread is formed at one end along the direction of the rotor axis, and the center of the male thread corresponds to this position.

[0019] Therefore, when the piston is in the neutral position, the entire drive shaft is inserted deep into the female thread of the rotor, which results in a closer arrangement of the cylinder and the motor, shortening the length along the axis and making it possible to obtain a more compact actuator.

[0020] (Features) In the actuator according to the present invention, it is preferable that the cylinders are a first cylinder and a second cylinder, both of which are cup-shaped, arranged on either side of the motor and open towards the motor, the drive shaft passes through the rotor, and a first piston housed within the first cylinder and a second piston housed within the second cylinder are connected to both ends of the drive shaft, respectively.

[0021] (effect) The actuator of this configuration has a cylinder and a piston on both sides of the motor. In this configuration, it is necessary to operate two pistons, but the rotor drives the drive shaft that holds both the first and second pistons, so the mechanism does not become complicated.

[0022] In this configuration, cup-shaped cylinders are used as the first and second cylinders, and when the piston is attached, the space between the piston and the bottom becomes a chamber, and the space on the opposite side can be open to the atmosphere.

[0023] In this case, the sealing structure of the chamber only requires that the outer surface of the piston and the inner surface of the cylinder be airtight, and no special consideration is required for the drive shaft. This makes it extremely easy to ensure airtightness of the entire device, resulting in a rational actuator.

[0024] (Features) In the actuator according to the present invention, a ball screw may be used for the screw engagement, and the rotation of the drive shaft around the axis may be restricted.

[0025] (effect) By using a ball screw as in this configuration, the motion resistance associated with the relative rotation between the rotor and the drive shaft is reduced. This reduces the tendency for the drive shaft to rotate in response to the rotation of the rotor, and the reciprocating movement of the drive shaft, whose rotation is restricted, becomes smooth. This results in an actuator with improved transmission efficiency, excellent operational responsiveness, and little vibration or noise.

[0026] (Features) In the actuator according to the present invention, the two spaces may be configured to be connected to chambers of two air suspension devices arranged on each wheel of the vehicle, respectively.

[0027] (effect) According to this configuration, the chamber connecting the two spaces may be, for example, a chamber related to the left and right wheels of the vehicle, or a chamber related to the front and rear wheels. In the case of the left and right wheels, it is possible to control the pressure of the outer chamber and the pressure of the inner chamber during cornering to suppress changes in the roll attitude. On the other hand, in the case of the front and rear wheels, it is possible to control the pressure of the front wheel chamber and the pressure of the rear wheel chamber when going over a step to suppress changes in the pitch attitude.

[0028] Furthermore, in this configuration, the motor thrust required to pressurize one side and depressurize the other side is small. For example, when turning, the vehicle leans outward, so that the outer chamber is pressurized and the vehicle height is lowered, and the inner chamber is depressurized and the vehicle height is raised. In order to stabilize the vehicle's posture at this time, the motor is driven to move the piston, and the differential pressure generated in each chamber is made equal to the differential pressure between the left and right wheels. Therefore, with this configuration, the load on the motor is small, and the actuator can be made more compact. [Brief description of the drawings]

[0029] [Figure 1] FIG. 1 is an explanatory diagram showing a usage mode of the actuator according to the first embodiment; [Diagram 2] FIG. 1 is a cross-sectional view showing a structure of an actuator according to a first embodiment. [Diagram 3] FIG. 1 is a perspective view showing a structure of an actuator according to a first embodiment; [Figure 4] FIG. 11 is a cross-sectional view showing the structure of an actuator according to a second embodiment. [Diagram 5] FIG. 11 is a perspective view showing a structure of an actuator according to a second embodiment; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0030] [First embodiment] (overview) 1 to 3 show a first embodiment of an actuator A according to the present invention. This actuator A is integrally equipped with a motor M and a cylinder S, and converts the rotational motion of the motor M into reciprocating motion and transmits it to a piston P attached to the cylinder S. This actuator A is used in, for example, an air suspension device of a vehicle B.

[0031] As shown in an example in Fig. 1, in a vehicle B in which a right wheel TR and a left wheel TL are supported by two chambers, i.e., two air springs AS, one actuator A of the present invention is provided for each of the left and right wheels. Fig. 1 is a view of the vehicle B as seen along the traveling direction while making a left turn. A cylinder S is provided in the center of the actuator A, and a piston P is located in the center of the cylinder S in the neutral state. The internal space of the cylinder S is divided by the piston P into a first chamber R1 and a second chamber R2 on both sides of the cylinder S, and the first chamber R1 is connected to the first air spring AS1 of the right wheel TR, and the second chamber R2 is connected to the second air spring AS2 of the left wheel TL.

[0032] In the case of this configuration, it is possible to control the vehicle to suppress changes in roll posture by pressurizing the outer air spring AS1 and depressurizing the inner air spring AS2 during cornering. To do this, the lateral G is calculated from the detection results of a vehicle speed sensor and a steering angle sensor (not shown), and air is supplied to the air spring AS1 on the outer side of the turn by moving the piston P in the direction in which the first chamber R1 contracts.

[0033] In this configuration, the thrust of the motor M that drives the piston P is small. For example, when turning, the vehicle B leans outward, so that the outer air spring AS1 is pressurized and the vehicle height is lowered, and the inner air spring AS2 is depressurized and the vehicle height is raised. In order to stabilize the posture of the vehicle B at this time, the motor M is driven to move the piston P, and the differential pressure generated in each of the air springs AS1, AS2 is made equal to the differential pressure associated with the left and right wheels TL, TR. Therefore, with this configuration, the load on the motor M is small, and the actuator A can be made compact.

[0034] Although not shown in the figures, the two first chambers R1 and second chambers R2 formed by the cylinder S and piston P can also be connected to the air springs AS for the front and rear wheels. In the case of front and rear wheels, when going over a step, it is possible to control the air springs AS of the front wheels to be depressurized and the air springs AS of the rear wheels to be pressurized, thereby suppressing changes in pitch attitude.

[0035] In this way, by controlling the roll and pitch attitudes of vehicle B, it is possible to improve the turning performance and step-crossing performance of vehicle B. In addition, it is also possible to improve the ease of getting on and off vehicle B by tilting vehicle B when stopped. Furthermore, it can be easily added to an air suspension already installed on vehicle B, providing actuator A with high versatility.

[0036] [Motor and stroke sensor] Various types of motors equipped with a stator M2 and a rotor M1 can be used as the motor M. The amount of movement of the piston P is determined by the amount of rotation of the motor M, and in this embodiment, the amount of movement of the piston P is measured using, for example, a stroke sensor 9.

[0037] Specifically, in order to measure the amount of movement of the male screw shaft 2, a stroke sensor 9 is disposed between the tip of the male screw shaft 2 and the first housing H1. The stroke sensor 9 can directly measure the movement of the end of the male screw shaft 2, making it easy and reliable to grasp the position of the piston P. In addition, wiring to the motor M and the like is also easy, making it possible to improve reliability and reduce costs. Note that, in addition to using the stroke sensor 9, for example, an encoder or resolver may be provided on a part of the rotor M1 to measure the rotation speed and rotation angle of the rotor M1 to grasp the amount of movement of the piston P.

[0038] [Control board] The amount of movement of the piston P is controlled by a control board 5 provided in the first housing H1. Although not shown, the vehicle B is provided with a vehicle speed sensor and a steering angle sensor. Based on the vehicle speed and steering angle data measured by these sensors, the control board 5 calculates the lateral G force generated in the vehicle B during steering. A map correlating the lateral G force with the stroke of the piston P is stored in the control board 5, and it is also possible to perform feedforward control of the motor M.

[0039] [Cylinder / Piston] The cylinder S is provided in a first housing H1 that houses the motor M. In this embodiment, both the motor M and the cylinder S are substantially cylindrical. A piston P supported by a drive shaft is provided inside the cylinder S so as to be capable of reciprocating motion. In particular, by forming the cylinder S from a cylindrical member and forming the cylinder S into a through structure with both ends open, the cylinder S can be easily manufactured.

[0040] The inside of the cylinder S is divided into a first chamber R1 and a second chamber R2 by the piston P, and each chamber alternates between an expanded state and a contracted state. As shown in Figures 2 and 3, a first shaft 31 and a second shaft 32 are screwed and connected to the piston P as a drive shaft 3. The first shaft 31 and the second shaft 32 are formed to have the same length to match the stroke of the piston P.

[0041] The cylinder S is formed in a cylindrical shape in which the piston P can slide. One end is fitted coaxially with a first housing H1 that houses the motor M, and a flange is fastened with bolts or the like, and the other end is fitted coaxially with a second housing H2, and a flange is fastened with bolts or the like. In particular, since one bottom of the cylinder S is also the first housing H1, the axis of the first shaft 31 and the axis of the male threaded shaft 2 are aligned with the same axis X, and are aligned with high precision.

[0042] The first shaft 31 is airtightly supported by a first seal portion s1 provided in the first housing H1, and the second shaft 32 is airtightly supported by a second seal portion s2 provided in the second housing H2. An annular piston seal SP is attached to the outer periphery of the piston P, and the piston P reciprocates while tightly abutting against the inner wall of the cylinder S. A first port p1 is formed in the first chamber R1, and a second port p2 is formed in the second chamber R2, each of which is connected to a predetermined air drive unit. With this configuration, the internal pressure of a separate air spring AS acts on both sides of the piston P, and the operating force required to move the piston P is the pressure difference between the left and right sides. This reduces the force borne by the motor M and the piston P, etc.

[0043] As in this embodiment, the actuator is more convenient because it has two spaces formed by the cylinder S and the piston P, i.e., the first chamber R1 and the second chamber R2. In other words, one motor M reciprocates one or two drive shafts 3 along the axis X, so that the first chamber R1 and the second chamber R2 can be alternately expanded or contracted in different phases. Therefore, the actuator can be widely applied to drive mechanisms that utilize a pair of increases and decreases in pressure, such as the air suspension device described above.

[0044] [Drive transmission] As shown in Figures 2 and 3, a male threaded shaft 2 having a male thread portion 2a on its outer circumferential surface is screwed and connected to the end of the first shaft 31. As a result, the male threaded shaft 2 becomes part of the drive shaft 3. With this configuration, the length of the mechanism along the axis X is significantly reduced compared to a typical mechanism in which the output shaft of the motor M and the drive shaft 3 of the piston P are connected using a separate gear or the like. Therefore, a compact actuator A can be obtained.

[0045] The rotor shaft 1 has a cylindrical hollow structure. A female threaded portion 1a is formed on a part of its inner surface to be screwed into the male threaded portion 2a. The male threaded shaft 2 is inserted into the female threaded portion 1a, and the two are screwed together with their respective axis centers X coinciding. The male threaded shaft 2 reciprocates as the rotor shaft 1 is driven to rotate.

[0046] With this configuration, the rotor shaft 1, which is a component of the motor M, is used as a component that converts the rotational drive of the motor M into the reciprocating motion of the piston P, making it possible to simplify the mechanism.

[0047] Furthermore, the male screw shaft 2, which is integral with the drive shaft 3, penetrates the inside of the rotor M1, which has a hollow structure, and the two are configured to overlap along the direction of the axis X. Generally, a mechanism with a piston requires a space for the drive shaft that reciprocates the piston, in addition to the arrangement space for the cylinder that contains the piston, and therefore a device housing of a certain size is required. However, with this configuration, the internal space of the rotor M1 can be used as part of the reciprocating space of the drive shaft 3, making it possible to make the device size more compact.

[0048] Furthermore, a part of the drive shaft 3 and a part of the rotor M1 are screwed together with their axis X coinciding. Therefore, the rotor M1 functions as a member that converts its own rotational drive into the reciprocating motion of the drive shaft 3. Moreover, compared to a typical drive transmission mechanism in which the output shaft of a motor and the drive shaft of a piston, which are arranged in series or in parallel, are connected using a separate gear or the like, the length or width of the mechanism is significantly reduced. Therefore, a compact actuator A can be obtained.

[0049] As shown in Figs. 2 and 3, a rotation restricting portion 6 is provided between the end of the male threaded shaft 2 and the first housing H1 so that the male threaded shaft 2 reciprocates without rotating relative to the first housing H1. The rotation restricting portion 6 is composed of a convex portion 6a and a groove portion 6b. At least one convex portion 6a is formed at the end of the male threaded shaft 2 so as to protrude in the radial direction. The groove portion 6b is formed longitudinally along the axis X of the male threaded portion 2a on the inner surface of the cylindrical space of the first housing H1 so that the convex portion 6a can be engaged therein. By forming the groove portion 6b integrally with the first housing H1, an increase in the number of parts is prevented, and the first housing H1 can be made compact.

[0050] The rotor shaft 1 is supported at both ends by the first housing H1 with two bearings 7. Of these, the bearing 7a, which is farther from the cylinder S, has a higher load capacity than the other bearing 7b. A female thread 1a is formed on the inner surface of this bearing 7a. The female thread 1a is formed on a portion of the rotor shaft 1 along the longitudinal direction, and by forming it in this position, the device can be made compact.

[0051] In other words, when the stroke of the piston P is taken into consideration, it is preferable that the female threaded portion 1a is screwed into the center of the male threaded portion 2a when the piston P is in a neutral state. Figure 2 shows this state. In this state, the motor M is disposed on the cylinder S side from the center in the longitudinal direction of the male threaded portion 2a. In this configuration, the large-diameter first housing H1 that houses the motor M and the large-diameter cylinder S are disposed adjacent to each other, so the overall length of the portion having the large diameter dimension is shortened.

[0052] Conversely, if the female thread portion 1a were formed at the end of the rotor shaft 1 closest to the cylinder S, the motor M would be placed upside down with respect to the position of the female thread portion 1a in Fig. 2. In other words, the motor M and the cylinder S would be placed apart by an amount equal to half the length of the male threaded shaft 2 protruding. If the first housing H1 and the cylinder S, both of which have large diameters, are separated from each other, the size of the entire device would increase, compromising compactness.

[0053] In either case, the overall length of the device is the same, but the overall compactness varies greatly depending on the arrangement of the large diameter portion. Therefore, with the configuration shown in Figure 2, it is possible to obtain actuator A with excellent mountability to vehicle B, for example.

[0054] Furthermore, in this configuration, a ball screw 8 is used to screw the male threaded portion 2a and the female threaded portion 1a together. This facilitates the relative rotation between the rotor shaft 1 and the male threaded shaft 2, reducing operational resistance. In addition, since the male threaded shaft 2 is less likely to be driven by the rotation of the rotor shaft 1, the sliding resistance of the rotation restricting portion 6 of the male threaded shaft 2 against the first housing H1 is also reduced. This improves the transmission efficiency from the rotor shaft 1 to the male threaded shaft 2, making it possible to obtain an actuator A that has excellent operational responsiveness and generates little vibration and noise. Note that a trapezoidal screw may be used instead of the ball screw 8.

[0055] Second Embodiment An actuator A according to the second embodiment is shown in Figures 4 and 5. In this embodiment, a cylinder S and a piston P which form a single space are provided on opposite sides of a motor M. The cylinders S include a cup-shaped first cylinder S1 and a cup-shaped second cylinder S2 which are connected to a first housing H1 housing the motor M.

[0056] A male threaded shaft 2 as a drive shaft 3 is disposed penetrating the rotor shaft 1, and a first piston P1 housed in a first cylinder S1 and a second piston P2 housed in a second cylinder S2 are attached to both ends of the male threaded shaft 2. The first piston P1 is connected to the male threaded shaft 2 via a first shaft 31, and forms a first chamber R1 together with the wall of the first cylinder S1. The second piston P2 is connected to the male threaded shaft 2 via a second shaft 32, and forms a second chamber R2 together with the wall of the second cylinder S2. The surface of the first piston P1 facing the motor M and the surface of the second piston P2 facing the motor M are open to the atmosphere. A first port p1 is provided in the first chamber R1, and a second port p2 is provided in the second chamber R2.

[0057] As shown in Fig. 4, the convex portion 6a and the groove portion 6b which are the rotation restricting portion 6 of the male threaded shaft 2 are provided on the side of the first cylinder S1. A second housing H2 which houses the rotation restricting portion 6 is connected to the first housing H1 which houses the motor M. The first cylinder S1 is further connected to this. Meanwhile, the second cylinder S2 is connected to the opposite side. A third housing H3 which houses the control board 5 is connected radially outward from the second cylinder S2.

[0058] In this configuration, the first piston P1 and the second piston P2 provided on either side of the motor M are operated simultaneously, but the rotor M1 only needs to rotate the male threaded shaft 2, which is the drive shaft 3, so the mechanism does not become complicated.

[0059] The first cylinder S1 and the second cylinder S2 are cup-shaped, and the first chamber R1 or the second chamber R2 is formed only on one side of the piston P. Therefore, in order to ensure airtightness, it is only necessary to provide a piston seal SP on the outer circumferential surface of each of the first piston P1 and the second piston P2, and there is no need to seal the sliding parts of the first shaft 31 or the second shaft 32. This makes it extremely easy to ensure airtightness of the entire device, and a rational actuator A can be obtained. [Industrial Applicability]

[0060] The actuator of the present invention includes a cylinder with a piston built in and a motor, and can be widely used as an actuator that reciprocates the piston by rotational driving of the motor. [Explanation of symbols]

[0061] 1a Female thread 2a Male thread 3 Drive shaft 8. Ball screw A actuator B Vehicle Medium motor M1 Rotor M2 Stator P piston P1 First piston P2 Second piston R1 Room 1 R2 2nd room S cylinder S1 First cylinder S2 No. 2 cylinder T-wheel X-axis center

Claims

1. a motor having a stator and a rotor; At least one cylinder disposed adjacent to the motor; a piston attached to a drive shaft and provided inside the cylinder; the rotor has a hollow structure, and the drive shaft is accommodated inside the rotor in a state in which a part of the drive shaft and a part of the rotor are screwed together while their axial centers are aligned, An actuator in which the drive shaft reciprocates along the axis as the rotor rotates.

2. 2. The actuator according to claim 1, further comprising two spaces defined by said cylinder and said piston.

3. a single cylinder is provided as the cylinder, and the piston is disposed in a state of dividing an interior of the cylinder into a first chamber and a second chamber; a male thread portion formed on a part of the drive shaft and a female thread portion formed on a part of the inner surface of the rotor are screwed together, 2. The actuator according to claim 1, wherein the female thread portion is provided at one of both ends of the rotor along the axis that is farther from the cylinder.

4. The cylinders include a first cylinder and a second cylinder, both of which are cup-shaped, and are provided so as to sandwich the motor and open toward the motor, 2. The actuator according to claim 1, wherein the drive shaft passes through the rotor, and a first piston housed in the first cylinder and a second piston housed in the second cylinder are connected to both ends of the drive shaft, respectively.

5. 2. The actuator according to claim 1, wherein a ball screw is used for the screw engagement, and rotation of the drive shaft about the axis is restricted.

6. 3. The actuator according to claim 2, wherein said two spaces are connected to chambers of two air suspension systems disposed on each wheel of the vehicle, respectively.

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