Ride-height adjustment with leaf spring

A suspension system includes a leaf spring, an actuator attached to the leaf spring, and an axle mount attached to the actuator. The actuator is disposed vertically between the leaf spring and the axle mount and is actuatable to change a distance between the leaf spring and the axle mount.

BACKGROUND

Vehicles typically include suspension systems. The suspension system of a vehicle is coupled to the vehicle frame and to at least one wheel of the vehicle. The suspension system absorbs and dampens shocks and vibrations from the wheels to the vehicle frame. One type of suspension system is a leaf suspension system. The leaf suspension system includes a leaf spring elongated along a longitudinal axis of the vehicle. The leaf spring includes ends attached to the vehicle frame, and an axle of the vehicle is supported by the leaf spring between the ends of the leaf spring. The suspension system is typically arranged so that an upward motion of the wheel, such as when the wheel hits a bump while the vehicle is in motion, loads the leaf spring.

DETAILED DESCRIPTION

A suspension system includes a leaf spring, an actuator attached to the leaf spring, and an axle mount attached to the actuator. The actuator is disposed vertically between the leaf spring and the axle mount and is actuatable to change a distance between the leaf spring and the axle mount.

The suspension system may further include a top plate disposed between the leaf spring and the actuator. The top plate may be directly attached to the leaf spring and to the actuator.

The suspension system may further include a U-bolt holding the top plate and the leaf spring together.

The actuator may be a first actuator, and the suspension system may further include a second actuator disposed vertically between the leaf spring and the axle mount. The first actuator and the second actuator may be oriented to actuate parallel to each other.

The suspension system may further include a first bottom plate directly attached to the first actuator and to the axle mount, and a second bottom plate directly connected to the second actuator and the axle mount. The axle mount may include a top axle-mount section and a bottom axle-mount section, and the first and second bottom plates may be directly attached to the top axle-mount section. The first and second bottom plates and the top axle-mount section may be integral.

The first bottom plate and the second bottom plate may be horizontally aligned.

The axle mount may be between the first actuator and the second actuator.

The actuator may be a linear actuator. The actuator may be oriented to actuate vertically.

The actuator may be electronically actuatable. The suspension system may further include a ride-height sensor coupled to the axle mount, and an electronic control unit communicatively coupled to the actuator and the ride-height sensor, and the electronic control unit may be programmed to actuate the actuator based on data from the ride-height sensor. The electronic control unit may be programmed to lengthen the actuator in response to data from the ride-height sensor indicating a decrease in ride height, and to shorten the actuator in response to data from the ride-height sensor indicating an increase in ride height.

The suspension system may further include an electronic control unit communicatively coupled to the actuator, and the electronic control unit may be programmed to shorten the actuator in response to an ignition switching to off.

The suspension system may further include an electronic control unit communicatively coupled to the actuator, and the electronic control unit may be programmed to shorten the actuator in response to a proximity of a key fob to a vehicle including the suspension system.

The leaf spring may be elongated along an axis, and the actuator may be closer to a center of the leaf spring than to either end of the leaf spring along the axis.

A suspension system30for a vehicle32includes a leaf spring34, at least one actuator36,38attached to the leaf spring34, and an axle mount40attached to the actuator36,38. The actuator36,38is disposed vertically between the leaf spring34and the axle mount40and is actuatable to change a distance between the leaf spring34and the axle mount40.

The suspension system30provides a useful way to adjust a ride height of the vehicle32at the suspension system30. The suspension system30permits the vehicle32to be lower for easier ingress and egress. The suspension system30can counterbalance light or heavy loading of the vehicle32, allowing for a similarly level ride regardless. The suspension system30can allow the vehicle32to be designed with less rake, i.e., a rear ride height greater than a front ride height. The suspension system30fits in a compact package space.

With reference toFIG. 1, the vehicle32may be any suitable type of vehicle, e.g., a car, pickup truck, van, sport utility vehicle, etc. As examples, the vehicle32be a cargo-carrying vehicle, e.g., a pickup truck (as shown inFIG. 1), a van, a sport utility vehicle, etc. The vehicle32may be of a body-on-frame construction, in which a frame42supports a body44that is a separate component from the frame42. In the example in which the vehicle32is a pickup truck, the body44may include a cab46and a bed48. As another example, the vehicle32may be of a unibody construction, in which the frame42and the body44of the vehicle32are a single component. The frame42and body44may be formed of any suitable material, for example, steel, aluminum, etc.

With reference toFIGS. 2-7, the vehicle32includes an axle50. The axle50includes a housing (not numbered) and houses shafts (not numbered) extending from the housing to rear wheels52to transfer rotation to the rear wheels52. The axle50may be a solid axle, i.e., the housing and the shaft are rotatable together as a unit about an axis perpendicular to a longitudinal axis of the vehicle32.

The suspension system30is coupled to the axle50. The suspension system30is coupled to the frame42. The suspension system30absorbs and dampens shocks and vibrations from the rear wheels52to the frame42. The suspension system30may be a rear suspension system, as shown in the Figures. In such an example, the axle50is a rear axle. As another example, the suspension system30may be a front suspension system for front wheels84. As set forth below, the suspension system30may include one or more actuators36,38, e.g., a first actuator36and a second actuator38. (The adjectives “first” and “second” are used throughout this document as identifiers and are not intended to signify importance or order.)

The leaf spring34is elongated from a first end54to a second end56along an axis A. The axis A may be oriented in a vehicle-forward direction, i.e., may be a longitudinal axis of the vehicle32. The leaf spring34may be straight or slightly bowed along the axis A. The ends54,56are coupled to the frame42. Both ends54,56may be fixed to the frame42, as shown inFIG. 2, or the first end54may be fixed to the frame42and the second end56may be movably attached to the frame42, such as via a shackle (not shown). The leaf spring34includes a plurality of plates58elongated between the ends54,56. The plates58are stacked transverse to the axis A, e.g., stacked vertically. The springiness of the leaf spring34comes from the bending of the plates58.

As set forth above, the suspension system30may include one or more actuators36,38, e.g., the first actuator36and the second actuator38in the example shown in the Figures. In the example including the first actuator36and the second actuator38, the axle mount40may be between the first actuator36and the second actuator38. The first actuator36may be disposed forward of a center of the leaf spring34along the axis A, and the second actuator38may be disposed rearward of the center of the leaf spring34along the axis A. The actuators36,38may be disposed closer to the center of the leaf spring34than to either of the ends54,56of the leaf spring34along the axis A.

In the example including the first actuator36and the second actuator38, the actuators36,38are oriented to actuate vertically and parallel to each other. The actuators36,38can thus actuate together to lift or lower the leaf spring34and the frame42relative to the axle mount40and the ground, changing the ride height of the rear of the vehicle32.

Each actuator36,38may be a linear actuator that is actuatable to change a distance between the leaf spring34and the axle mount40. The actuators36,38are actuatable in two directions, i.e., each actuator36,38is actuatable both to lengthen and to shorten the distance between the leaf spring34and the axle mount40. For example, the actuator36,38may be a reciprocating ball screw.

The actuator36,38, e.g., both the first actuator36and the second actuator38, is disposed vertically between the leaf spring34and the axle mount40; in other words, the leaf spring34is above the actuator36,38, and the axle mount40is below the actuator36,38. The actuator36,38may be disposed directly between the leaf spring34and the axle mount40; i.e., the leaf spring34and the axle mount40are collinear with each actuator36,38.

Each actuator36,38is attached to the leaf spring34and to the axle mount40. Each actuator36,38may be attached indirectly to the leaf spring34via a top plate60. Each actuator36,38may be attached indirectly to the axle mount40via one or more bottom plates64,66. Each actuator36,38may be attached to one of the bottom plates64,66by, e.g., fasteners, welding, adhesives, etc. For example, the first actuator36and the second actuator38may be attached to the bottom plates64,66, respectively.

The suspension system30may include the top plate60disposed between the leaf spring34and the actuator36,38, e.g., both the first actuator36and the second actuator38. The top plate60may be adjacent to and contacting the leaf spring34and the actuator36,38, e.g., both the first actuator36and the second actuator38. The top plate60may be elongated along the axis A. The top plate60may be shaped to accommodate the actuator36,38, e.g., both the first actuator36and the second actuator38. The top plate60may have a width approximately equal to a width of the leaf spring34.

The top plate60may be directly attached, i.e., attached with no intervening components other than a fastener, to the leaf spring34and to the actuator36,38, e.g., both the first actuator36and the second actuator38. For example, two U-bolts62may hold the top plate60and the leaf spring34together by compressing the top plate60to the leaf spring34vertically. The actuator36,38, e.g., both the first actuator36and the second actuator38, may be attached to the top plate60by, e.g., fasteners, welding, adhesives, etc.

The bottom plates64,66may be shaped to accommodate the actuators36,38. In the example including the first actuator36and the second actuator38, the bottom plates64,66may include the first bottom plate64and the second bottom plate66. The first bottom plate64may be directly attached to the first actuator36and to the axle mount40, and the second bottom plate66may be directly attached to the second actuator38and the axle mount40. The first bottom plate64and the second bottom plate66are horizontally aligned with each other, i.e., disposed at the same height as each other.

The axle mount40may include a top axle-mount section68and a bottom axle-mount section70. The top axle-mount section68and the bottom axle-mount section70may be shaped to together rotatably hold the axle50. The first and second bottom plates64,66may be integral with one of the top axle-mount section68and the bottom axle-mount section70. As shown in the Figures, the first and second bottom plates64,66are integral with the top axle-mount section68.

With reference toFIG. 8, the vehicle32includes an electronic control unit (ECU)72. The ECU72is a microprocessor-based controller. The ECU72includes a processor, memory, etc. The memory of the ECU72includes memory for storing instructions executable by the processor as well as for electronically storing data and/or databases.

The ECU72may transmit and receive data through a communications network74such as a controller area network (CAN) bus, Ethernet, WiFi, Local Interconnect Network (LIN), onboard diagnostics connector (OBD-II), and/or by any other wired or wireless communications network. The ECU72may be communicatively coupled to the actuator36,38(e.g., both the first actuator36and the second actuator38), front ride-height sensors76, rear ride-height sensors78, an ignition80, a key-fob proximity sensor82, and other components via the communications network74.

The ride-height sensors76,78are positioned to detect a relative position of the frame42and one of the rear wheels52or front wheels84. The front ride-height sensors76are coupled to the frame42and to the front wheels84of the vehicle32, and the rear ride-height sensors78are coupled to the frame42and to the rear wheels52. The ride-height sensors76,78may have one end fixed relative to the frame42and the other end fixed relative to the front or rear wheels52,84, e.g., by being fixedly coupled directly or indirectly to the axle mount40. The ride-height sensors76,78may be any suitable sensors for detecting the relative position of the frame42and the front or rear wheels52,84, e.g., a rotatable arm and a detector detecting the degree of rotation such as a rotary encoder, a potentiometer etc.; a rod slidable in a cylinder and a detector detecting the position of the rod in the cylinder such as via capacitance, electrical resistance, a linear encoder, etc.; or any other suitable sensor type.

The ECU72is programmed to actuate the actuator36,38(e.g., both the first actuator36and the second actuator38), i.e., to lengthen or shorten the actuator36,38. For example, the ECU72may be programmed to actuate the actuator36,38based on an input from an operator of the vehicle32. The ECU72may actuate the actuators36,38identically, i.e., may actuate the first actuator36and the second actuator38to move simultaneously and by identical distances.

The input may be provided via a button, switch, etc., in a passenger cabin of the vehicle32or via a command from a portable electronic device in communication with the ECU72such as a key-fob or a mobile phone.

Alternatively or additionally, the ECU72may be programmed to actuate the actuator36,38based on data from the ride-height sensors76,78. For example, the ECU72may be programmed to lengthen the actuator36,38in response to data from the rear ride-height sensors78indicating a decrease in ride height, and to shorten the actuator36,38in response to data from the rear ride-height sensors78indicating an increase in ride height. The magnitude of actuation may be based on the magnitude of change in ride height. In other words, the ECU72may be programmed to actuate the actuator36,38to counteract a change in ride height, e.g., from loading or unloading the bed48of the vehicle32.

Alternatively or additionally, the ECU72may be programmed to shorten the actuator36,38in response to the ignition80switching off. The suspension system30may thus bring the cab46closer to the ground when an occupant is likely to be exiting the cab46soon. The ECU72may be programmed to adjust the actuator36,38to a first preset height, e.g., to a minimum height. The ECU72may be programmed to lengthen the actuator36,38upon, e.g., starting the vehicle32, i.e., switching the ignition80on. The ECU72may be programmed to adjust the actuator36,38to a second preset height greater than the first preset height.

Alternatively or additionally, the ECU72may be programmed to shorten the actuator36,38in response to a proximity of the key fob to the vehicle32, as detected by the key-fob proximity sensor82. In particular, the ECU72may be programmed to shorten the actuator36,38in response to a distance of the key fob to the key-fob proximity sensor82decreasing from above a distance threshold to below the distance threshold. The distance threshold may be chosen based on making a time to walk the distance threshold to the vehicle32slightly longer than a length of time to shorten the actuator36,38, or the distance threshold may be chosen to correspond to a maximum range of the key-fob proximity sensor82. The suspension system30may thus bring the cab46closer to the ground when an operator is likely to be entering the cab46soon. The key-fob proximity sensor82may be any sensor suitable for sensing a signal from a key fob within a short range of the vehicle32, e.g., one or more antennas for detecting radio pulses from the key fob.