Patent Application
20190054915
The present disclosure relates generally to generally relates to brake assist systems and, more particularly, to a system and method for automatically applying service brakes to assist with the steering operations of a mobile vehicle.
During the operation of tracked or untracked vehicles, the application of the vehicle brake system to assist steering operations is often desirable. For example, in inclement weather conditions, vehicle steering operations may become difficult, thereby leading to improper alignment and positioning of an operating vehicle, which, in turn, may require frequent application of the vehicle service brakes to maintain good steering control. Additionally, under such conditions, it is also difficult to increase vehicle speed while maintaining appropriate machine guidance.
To address such concerns, some conventional approaches employ the use of propel hydrostatic relief valves and engine braking to support panic stopping to meet standard requirements. Drawbacks to such approaches, however, include increased engine over-speeds. As such, there is a need in the art for an improved service brake system to assist with vehicle steering that is low cost, limits engine over-speed during a panic stop situation, and provides more efficient steering guidance performance.
According to an aspect of the present disclosure, a brake assist system is disclosed for assisting the steering operations of a mobile vehicle. The brake assist system comprises a service brake assembly comprising a first brake device and a second brake device. An auxiliary control assembly coupled to the service brake assembly, the auxiliary control assembly comprising a main valve circuit and a secondary valve circuit fluidly coupled to an auxiliary supply source. An electronic control unit communicatively coupled to the auxiliary control assembly, wherein the electronic control unit is configured to receive an input signal indicative of a vehicle operating parameter comprising at least one of a steering angle generated by a vehicle guidance system or a vehicle speed error and generate a control signal to activate the main and secondary valve circuits, wherein activation of the main and secondary valve circuits includes proportionally controlling an output of at least two control valves arranged in the main and secondary valve circuits to supply a pressurized flow of fluid is applied to at least one of the first or second brake devices to assist steering operations of the vehicle.
Other features and aspects will become apparent by consideration of the detailed description and accompanying drawings.
The detailed description of the drawings refers to the accompanying figures in which:
Referring to
The primary control assembly 102 can comprise at least one foot operated control mechanism 103 coupled to a primary hydraulic circuit 110 to allow for manual activation of the left or right service brake 130a, 130b via an operator input (e.g., foot engagement of pedal). In some embodiments, the primary hydraulic circuit 110 can comprise cylinders 111, 113 arranged in pairs and respectively associated with a corresponding control valve assembly 114a, 114b. Each control valve assembly 114a, 114b can comprise a first and a second valve circuit 115, 116 collectively arranged to define a first and a second primary supply line 117a, 117b that supplies pressurized fluid to the left and right service brakes 130a, 130b. In various embodiments, the first and second valve circuits 115, 116 can comprise a plurality of control valves, including, but not limited to, blocker valves, pilot valves, relief valves, or combinations thereof that are arranged to control the flow of pressurized fluid supplied to service brakes 130a, 130b. For example, as illustrated in
The auxiliary control assembly 104 (
The auxiliary valve circuit 128 can comprise a main auxiliary valve 122 coupled to at least two secondary auxiliary valves 124a, 124b to define a first and a second auxiliary supply line 125a, 125b. Each valve 122, 124a, and 124b can be communicatively coupled to and controlled by an electronic control unit 211 housed within a power module 212 as will be discussed with reference to
The main auxiliary valve 122 can be arranged to modulate the available pressure from the auxiliary supply source 120 to each of the secondary auxiliary valves 124a, 124b such that adequate fluid and pressure levels are maintained when supplying fluid to service brakes 130a, 130b. In embodiments, the main and secondary valves 122, 124a, 124b can comprise electrohydraulic pressure valves or other suitable control valves. For example, the main auxiliary valve 122 can comprise a variable pressure valve that is arranged to regulate pressure at the valve inlet to maintain an appropriate pressure level. Each of the secondary auxiliary valves 124a, 124b can comprise selector valves or similar devices.
A first and a second shuttle valve 140, 142 can be arranged downstream of the primary and auxiliary control assemblies 102, 104 to allow for selective activation of the left or right service brake 130a, 130b via either the primary control assembly 102 or the secondary control assembly 104. In various embodiments, the first and second shuttle valves 140, 142 can comprise shuttle valves, for example, which are arranged to provide unidirectional flow and to prevent the backwards flow of fluid in the primary and auxiliary supply lines 117a, 117b and 125a, 125b.
As depicted in
With respect to
Referring now to
In embodiments, a harvesting structure 216 can be coupled to the forward portion 204a of the body frame 204 and arranged to extend outwardly and away from the body frame 204. As depicted, in some embodiments, the harvesting structure 216 can comprise one or more cotton picking units 215, a cotton stripper header, or other suitable harvesting structures (e.g., corn head or sugarcane harvesters), which are arranged to engage a surface of the field 250 for removal of crops such as cotton or grains. In the example embodiment, a feeder 220 can additionally be coupled to the body frame 204 and is arranged to receive cotton, or other crops, from an accumulator 222 as the crop is removed from the field 250. The accumulated crop is then compressed by and transferred from the feeder 220 to a baler 224 for bundling.
As shown in further detail in
Referring to
In other embodiments, such as in vehicle guidance systems (e.g., mechanical row sensing or satellite guidance systems), the steering angle can be determined based on a position error of the work machine 200. The position error, similar to the steering angle, could also be used as an input into a look-up table to determine the required amount of service brake application. In guidance systems such as John Deere RowTrak or AutoTrak, the position error could be used to provide an additional output of service brake application to assist the steering axle in making the position correction of work machine 200 when it has deviated from a preferred path. For example, as the vehicle guidance system commands a steering angle of the steering axle based on the position error, the guidance system could generate an output signal to control the amount of service brake application to the left or right service brake 130a, 130b. This is particularly advantageous to help facilitate driving in inclement weather and/or poor traction conditions (e.g., wet or muddy harvest conditions) where vehicle guidance is desired, but the difficulty of obtaining correct responses from the steering axle is significantly increased or no longer possible due to poor guide wheel traction.
Additionally, in contrast to conventional systems, where manual application of the service brakes disengages the vehicle guidance system and requires manual steering of the vehicle in inclement weather conditions, the present disclosure overcomes such limitations by permitting simultaneous engagement of both the primary control assembly 102 and the vehicle guidance system. For example, if inclement weather conditions exist, rather than disengaging the vehicle guidance system and allowing an operator to control the work machine 200 manually via the primary control assembly 102, steering operations are controlled automatically via the auxiliary control assembly 104 while the guidance system remains engaged.
In yet other embodiments, the vehicle operating parameter can further comprise a vehicle speed value (e.g., a calculated error between an actual and a commanded vehicle speed). For example, in panic stop situations where an operator commands a quick deceleration through a hydro handle actuation or other control means and hydrostatic braking or engine braking is limited or not possible, the electronic control unit 211 will activate the auxiliary control assembly 104 to engage at least one of service brakes 130a, 130b. This in turn, assists in deceleration of the work machine 200 and helps to prevent downstream drivetrain and pump over-speed by limiting the amount of engine over-speed. Such protection is advantageous in that it allows for optimal sizing of pumps (e.g., supply source 120) for rated and below rated speed performance without the concern of over-speed.
In yet other embodiments, instead of using the steering angle or the vehicle speed, direct hydraulic feedback could be used as the input signal to the electronic control unit 211 for activating the auxiliary control assembly 104.
As discussed above, once the vehicle operating parameter is received, the electronic control unit 211 generates an output signal that activates the auxiliary control assembly 104 at 304. For service brake assist to occur, at least two valves (i.e., the main auxiliary valve 122 and at least one of the secondary auxiliary valves 130a, 130b) must be actuated, which serves as a safety interlock, to prevent inadvertent application of the auxiliary control assembly 104. Upon activation, the main auxiliary valve 122 modulates the available pressure from the auxiliary supply source 120 to allow flow to pass through the secondary auxiliary valves 130a, 130b, which are arranged to control the flow of fluid in supply lines 125a, 125b (i.e., an increase or decrease in fluid supplied to shuttle valves 140, 142).
Next at 308, shuttle valves 140, 142 are opened to supply the pressurized fluid to either or both of service brakes 130a, 130b to exert a corresponding braking force on the service brakes 130a, 130b (i.e., engage service brakes) associated with either the forward or rear wheels 205, 207 at 310. The braking force is proportional to the applied pressure and degree of opening of the valves 122, 124a and/or 124b. In some embodiments, the automatic engagement of the service brakes 130a, 130b via the auxiliary control assembly 104 can be overwritten via an operator input at 304. For example, if a vehicle operator chooses to disengage the auxiliary control assembly 104, an override control signal is sent to the electronic control unit 211 at 309 to activate the primary control assembly 102 and deactivate the auxiliary control assembly 104.
As previously discussed with reference to
Without in any way limiting the scope, interpretation, or application of the claims appearing below, a technical effect of one or more of the example embodiments disclosed herein is a system and method for automatically applying service brakes to assist with the steering operations of a mobile vehicle. The present disclosure is particularly advantageous in that it optimizes machine performance by offering service brake assist steering to vehicles with non-powered axles which allows for axles to be closer to the turning and to more precisely replicate the steering ability of a powered rear axle.
While the above describes example embodiments of the present disclosure, these descriptions should not be viewed in a limiting sense. Rather, other variations and modifications may be made without departing from the scope and spirit of the present disclosure as defined in the appended claims.
