Suspension system with pitch stiffness control
A suspension system of a vehicle can provide configurable stiffness and damping characteristics. The system can include a plurality of shock absorbers, one or more valve assemblies, and a plurality of accumulators. The plurality of shock absorbers, which can be synchronous or non-synchronous, each correspond to a respective wheel of a vehicle. The valve assembly is configured for controlling hydraulic fluid in the plurality of shock absorbers to achieve a plurality of suspension modes affecting bounce, pitch, roll, and warp. The valve assemblies can be controlled to manage pitch stiffness of the vehicle in response to detected conditions, such as longitudinal and lateral dynamics, with overrides in response to vertical acceleration and/or damper displacement. Accordingly, the handling improvement provided by varying suspension modes is balanced with a desire to provide improved ride characteristics.
1 . A method for managing a suspension system of a vehicle, the method comprising:
obtaining, by a processor, sensor data from at least one sensor of the vehicle, the sensor data indicating a torque demand and a longitudinal acceleration of the vehicle;
determining, based on the sensor data, a suspension mode for the vehicle; and
transmitting, using control circuitry, a control signal for achieving the suspension mode to a control valve that is operable to fluidly connect each of multiple hydraulic lines to each other, the multiple hydraulic lines being fluidly connected to multiple shock absorbers of the vehicle, wherein:
in accordance with a determination that the sensor data indicates that the torque demand exceeds a first threshold, the control signal includes an instruction to operate the control valve to fluidly connect each of the multiple hydraulic lines; and
in accordance with a determination that the sensor data indicates that the longitudinal acceleration does not exceed a second threshold, the control signal includes an instruction to operate the control valve to fluidly separate the multiple hydraulic lines.
2 . The method of claim 1 , wherein:
the sensor data further indicates a torque rate demand; and
if the sensor data indicates that the torque rate demand exceeds a third threshold, the control signal includes the instruction to operate the control valve to fluidly connect each of the multiple hydraulic lines.
3 . The method of claim 1 , wherein the suspension mode is one of multiple available modes comprising:
a first mode in which the control valve is open to fluidly connect two of the multiple hydraulic lines to each other; and
a second mode in which the control valve is closed to fluidly separate the two of the multiple hydraulic lines from each other.
4 . The method of claim 3 , wherein:
in the first mode, the multiple shock absorbers are fluidly connected to each other to facilitate adjustments to a roll stiffness of the vehicle; and
in the second mode, the multiple shock absorbers are fluidly separated from each other to facilitate adjustments to the roll stiffness of the vehicle and a pitch stiffness of the vehicle.
5 . The method of claim 1 , wherein:
the sensor data further indicates a vertical acceleration of the vehicle; and
when the sensor data indicates that the vertical acceleration exceeds a fourth threshold, the control signal includes the instruction to operate the control valve to fluidly separate the multiple hydraulic lines.
6 . The method of claim 5 , wherein:
the sensor data further indicates a damper displacement of at least one of the multiple shock absorbers of the vehicle; and
when the sensor data indicates that the damper displacement exceeds a fifth threshold, the control signal includes the instruction to operate the control valve to fluidly separate the multiple hydraulic lines.
7 . The method of claim 1 , wherein:
the control valve is a first control valve;
the vehicle comprises a second control valve;
the multiple shock absorbers comprise:
a first shock absorber comprising a first compression volume and a first rebound volume;
a second shock absorber comprising a second compression volume and a second rebound volume;
a third shock absorber comprising a third compression volume and a third rebound volume; and
a fourth shock absorber comprising a fourth compression volume and a fourth rebound volume;
the first control valve is operable to controllably fluidly interconnect the second rebound volume, the third compression volume, the fourth rebound volume, and the first compression volume; and
the second control valve is operable to controllably fluidly interconnect the first rebound volume, the fourth compression volume, the third rebound volume, and the second compression volume.
8 . A method for managing a suspension system of a vehicle, the method comprising:
obtaining, by a processor, sensor data from at least one sensor of the vehicle, the sensor data indicating a vertical acceleration of the vehicle;
based on the sensor data, determining a suspension mode for the vehicle; and
transmitting, using control circuitry, a control signal for achieving the suspension mode to a control valve that is operable to fluidly connect each of multiple hydraulic lines to each other, the multiple hydraulic lines being fluidly connected to multiple shock absorbers of the vehicle.
9 . The method of claim 8 , wherein, when the sensor data indicates that the vertical acceleration exceeds a threshold, the control signal includes an instruction to operate the control valve to fluidly connect the multiple hydraulic lines.
10 . The method of claim 9 , wherein the threshold is determined based on a longitudinal speed of the vehicle.
11 . The method of claim 8 , wherein the suspension mode is one of multiple available modes comprising:
a first mode in which the control valve is open to fluidly connect two of the multiple hydraulic lines to each other; and
a second mode in which the control valve is closed to fluidly separate the two of the multiple hydraulic lines from each other.
12 . The method of claim 11 , wherein;
in the first mode, the multiple shock absorbers are fluidly connected to each other to facilitate adjustments to a roll stiffness of the vehicle; and
in the second mode, the multiple shock absorbers are fluidly separated from each other to facilitate adjustments to the roll stiffness of the vehicle and a pitch stiffness of the vehicle.
13 . The method of claim 8 , wherein:
the control valve is a first control valve;
the vehicle comprises a second control valve;
the multiple shock absorbers comprise:
a first shock absorber comprising a first compression volume and a first rebound volume;
a second shock absorber comprising a second compression volume and a second rebound volume;
a third shock absorber comprising a third compression volume and a third rebound volume; and
a fourth shock absorber comprising a fourth compression volume and a fourth rebound volume;
the first control valve is operable to controllably fluidly interconnect the second rebound volume, the third compression volume, the fourth rebound volume, and the first compression volume; and
the second control valve is operable to controllably fluidly interconnect the first rebound volume, the fourth compression volume, the third rebound volume, and the second compression volume.
14 . A semiconductor device for a vehicle, the semiconductor device comprising:
circuitry configured to:
obtain sensor data from at least one sensor of the vehicle, the sensor data indicating a damper displacement of at least one of multiple shock absorbers of the vehicle;
determine, based on the sensor data, a respective suspension mode for the vehicle; and
transmit a control signal for achieving the respective suspension mode to a control valve that is operable to fluidly connect each of multiple hydraulic lines to each other, the multiple hydraulic lines being fluidly connected to the multiple shock absorbers, wherein:
in accordance with a determination that the damper displacement exceeds a threshold, the respective suspension mode is a first mode in which the control valve is open to fluidly connect the multiple hydraulic lines to each other; and
in accordance with a determination that the damper displacement does not exceed the threshold, the respective suspension mode is a second mode in which the control valve is closed to fluidly separate at least some of the multiple hydraulic lines from each other.
15 . The semiconductor device of claim 14 , wherein:
in accordance with the determination that the damper displacement exceeds the threshold, the control signal includes an instruction to operate the control valve to fluidly connect the multiple hydraulic lines to each other; and
in accordance with the determination that the damper displacement does not exceed the threshold, the control signal includes an instruction to operate the control valve to fluidly separate the at least some of the multiple hydraulic lines from each other.
16 . The semiconductor device of claim 14 , wherein the threshold is determined based on a longitudinal speed of the vehicle.
17 . The semiconductor device of claim 14 , wherein:
in the first mode, the multiple shock absorbers are fluidly connected to each other to facilitate adjustments to a roll stiffness of the vehicle; and
in the second mode, at least some of the multiple shock absorbers are fluidly separated from each other to facilitate adjustments to the roll stiffness of the vehicle and a pitch stiffness of the vehicle.
18 . The semiconductor device of claim 14 , wherein:
the control valve is a first control valve;
the vehicle comprises a second control valve;
the multiple shock absorbers comprise:
a first shock absorber comprising a first compression volume and a first rebound volume;
a second shock absorber comprising a second compression volume and a second rebound volume;
a third shock absorber comprising a third compression volume and a third rebound volume; and
a fourth shock absorber comprising a fourth compression volume and a fourth rebound volume;
the first control valve is operable to controllably fluidly interconnect the second rebound volume, the third compression volume, the fourth rebound volume, and the first compression volume; and
the second control valve is operable to controllably fluidly interconnect the first rebound volume, the fourth compression volume, the third rebound volume, and the second compression volume.
19 . The semiconductor device of claim 14 , wherein each of the multiple hydraulic lines extends from the control valve to connect at least two of the multiple shock absorbers to each other.