JPH0353975Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial field of application] The present invention relates to a steering assist amount control device for a power steering system for a vehicle, and particularly relates to a steering assist amount control device for a power steering device for a vehicle. Steering assistance of a vehicle power steering system in a vehicle that has a control mechanism that enables differential movement (or does not limit differential movement) in a non-active state and disables differential movement (or limits differential movement) in an active state. It relates to a quantity control device.

[Prior art]

Conventionally, in this type of power steering device for a vehicle, when a steering wheel is rotated, a steering assist mechanism performs a predetermined steering operation in response to the rotation, regardless of whether the control mechanism is activated or deactivated. The assist amount assists the driver's steering operation and reduces the driver's steering force when turning the vehicle.

[Problem that the invention attempts to solve]

However, in a vehicle having the control mechanism, when the control mechanism is in the operating state and the driver turns the steering wheel to turn the vehicle, the turning radii of the first and second drive wheels change. Despite the difference, because the differential mechanism is disabled (or differential limited), there is a sufficient rotational speed difference between the first and second drive wheels that is necessary for the vehicle to turn. When the control mechanism is not in operation, that is, when the differential device is capable of differential operation (or when the differential is not limited), the straightness of the vehicle increases and the restoring force of the steering wheel increases. . However, in the above-mentioned conventional power steering system for a vehicle, even when the control mechanism is in an operating state, the driver's steering operation is assisted by the same amount of steering assist force as when the control mechanism is in an inactive state. The steering wheel operation when the control mechanism is activated is heavier than when the control mechanism is not activated due to the increased restoring force of the steering wheel, and the steering performance of the vehicle deteriorates. There's a problem.

The purpose of the present invention is to solve the above-mentioned problem by enabling the driver to operate the steering wheel with light force even when the control mechanism is in the operative state, just as when the same mechanism is in the non-operative state. The present invention provides a steering assist amount control device for a power steering device for a vehicle, which improves the steering performance of the vehicle.

[Means for solving problems]

In order to solve this problem, the structural feature of the present invention is that, as shown in FIG. It is applied to a vehicle that has a control mechanism 3 that enables differential movement (or does not limit differential movement) and disables differential movement (or limits differential movement) in its operating state, and controls the amount of steering assist by steering assist mechanism 4. The power steering system for a vehicle is configured to reduce the steering operation force of the driver according to the detection means 5, which detects the non-operating state and the operating state of the control mechanism 3, and the control mechanism 3 according to the detection. determines a control amount representing a first steering assist amount when the control mechanism 3 is in an inactive state, and determines a control amount representing a second steering assist amount larger than the first steering assist amount when the control mechanism 3 is in an active state. control amount determining means 6 to output a control signal corresponding to the determined control amount to the steering assist mechanism 4 to set the steering assist amount by the steering assist mechanism 4 to the first control amount;
Alternatively, the output means 7 for controlling the second steering assist amount is provided.

[Functions and effects of the idea]

In the present invention configured as described above, the detection means 5 detects the non-operating state and the operating state of the control mechanism 3, and based on this detection, the control amount determining means 6
If the control mechanism 3 is in an inactive state, a control amount representing a first steering assist amount is determined, and if the control mechanism 3 is in an active state, a control amount representing a second steering assist amount larger than the first steering assist amount is determined. Then, the output means 7 controls the steering assist mechanism 4 based on this determined control amount.
The steering assist amount is determined as the first or second steering assist amount. As a result, the amount of steering assistance when the control mechanism 3 is in the operating state is larger than when the same mechanism 3 is in the non-acting state, so the differential gear 2 when the control mechanism 3 is not in the operating state is Even if the differential is disabled (or the differential is limited), the steering operation will not become difficult, and the steering performance of the vehicle will be improved.

[Embodiment] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 2 shows a four-wheel drive vehicle equipped with a drive device 20 that drives left and right front wheels 10a, 10b and left and right rear wheels 11a, 11b. , a power steering device 30 that is applied to the four-wheel drive vehicle and steers the left and right front wheels 10a, 10b, and an electric control device 4 that controls the steering assist amount of the power steering device 30 according to the state of the drive device 20.
0 is schematically shown.

The drive device 20 includes an engine 21, and the driving force of the engine 21 is transmitted to a central differential device 22a. Central differential device 22a
As shown in FIG. 3, a differential case 50, a side gear 51 and a shaft 52 integrated therewith,
A pinion shaft 53 that distributes power from the differential case 50 to the shaft 52 via the side gear 51
A bevel gear type differential device configured with a pinion-on-gear 54, etc., which distributes the driving force from the engine 21 to the main drive wheels 23a, 23b to create a front wheel differential device 22b and a rear wheel differential device. 22c, respectively. The front wheel differential device 22b includes left and right front wheel drive shafts 24a, 24 for the left and right front wheels 10a, 10b.
b, and the central differential 22a
The driving force transmitted from the left and right front wheel drive shafts 24a,
24b and is transmitted to the left and right front wheels 10a, 10b. The rear wheel differential device 22c is for the left and right rear wheels 1.
1a, 11b via left and right rear wheel drive shafts 25a, 25b, and the driving force transmitted from the central differential device 22a is transmitted to the left and right rear wheel drive shafts 25a, 25.
b and is transmitted to the left and right rear wheels 11a, 11b. Note that the front wheel differential device 22b and the rear wheel differential device 22c are bevel gear type differential devices as shown in FIG. 3, like the central differential device 22a.

In addition, the differential devices 22a, 22b, 22c include
The same devices 22a, 22b,
lock mechanisms 26a, 26 for disabling each differential operation of the devices 22c and enabling each differential operation of the devices 22a, 22b, 22c in their respective inactive states;
b and 26c are attached respectively. Lock mechanism 2
6a or 26b, 26c, as shown in FIG. The locking sleeve 63 is configured to move in the left-right direction in FIG. has been done. This locking mechanism 26a or 26b, 26c
is normally in a non-operating state, and in this state, the lock lever 62 is biased counterclockwise in FIG. 3 by a spring 64 connected between the case 60 and the lever 62, and the lock sleeve 63 is in the position shown in FIG. Since the engaging tooth 50a and the engaging tooth 52a are separated at this time, the differential device 22a or 22b, 22c is in a state in which differential operation is possible.

Further, the lock mechanisms 26a, 26b, 26c are
As shown in FIGS. 2 and 3, wires 27a, 27b, 27c connected to each lock lever 62
An operating lever 28 arranged near the driver's seat by
a, 28b, and 28c, respectively, and are brought into operation by each operation of the operating levers 28a, 28b, and 28c. In this state, the lock lever 62 is pulled to the right in FIG. 3 by the wires 27a, 27b, and 27c and swings clockwise in the figure, and the lock sleeve 63 moves to the left in the figure and engages with the engagement tooth 50a. By connecting the matching teeth 52a, independent rotation of the differential case 50 and shaft 52 of the differential device 22a, 22b, 22c is disabled, and differential operation of the differential device 22a, 22b, 22c is disabled. .

As shown in FIG. 2, the power steering device 30 includes a flexible coupling 32a at the lower end of a steering shaft 32 that rotates when a steering handle 31 is operated.
The power steering gear box 33 has a built-in servo valve 33A assembled through the servo valve 33A, and a power cylinder 33B in which the supply and discharge of pressure oil is controlled by the switching operation of the servo valve 33A. Engine 2 at the inlet
Hydraulic pump 34 driven by conduit P1
The reservoir 34 of the hydraulic pump 34 is connected to the outlet of the servo valve 33A through a conduit P2.
a is connected. In addition, the power cylinder 33
A hydraulic pump 34 and a reservoir 34a are installed on the peripheral wall of the housing B by switching the servo valve 33A.
A high-pressure side oil passage and a low-pressure side oil passage are provided for the power cylinder 33B, which are selectively connected to the power cylinder 33B, and the oil discharged from the pump 34 supplies power through the high-pressure side oil passage in response to the switching operation of the servo valve 33A. The oil is supplied to the high-pressure side oil chamber of the cylinder 33B, while discharged oil from the low-pressure side oil chamber of the power cylinder 33B flows into the reservoir 34a through the low-pressure side oil passage, the servo valve 33A, and the conduit P2. As a result, the power cylinder 33b operates to generate a predetermined steering assisting force using hydraulic pressure.

Further, a bypass passage is provided on the peripheral wall of the power cylinder 33B to communicate the high pressure side oil passage and the low pressure side oil passage, and this bypass passage has a bypass valve 35 having an electrically driven solenoid.
is installed. The bypass valve 35 controls the opening degree of the bypass passage in proportion to the magnitude of a control signal given from a drive circuit 41 of an electric control device 40, which will be described later. When the opening degree increases, the high pressure of the power cylinder 33B increases. The hydraulic pressure in the side oil chamber decreases, and the steering assisting force generated by the hydraulic pressure of the power cylinder 33B decreases. In the power steering system illustrated here, the bypass valve 35 is arranged in a bypass passage provided on the peripheral wall of the power cylinder 33B, but the bypass valve 35 is arranged in a bypass passage provided in the circumferential wall of the power cylinder 33B. It may be arranged in a bypass conduit provided in a part.

The electric control device 40 includes a vehicle speed sensor 42 that picks up the rotation of the output shaft of the transmission or the wheels 10a or 10b, 11a, 11b and generates a pickup signal with a frequency proportional to the number of rotations, that is, the vehicle speed U, and a control lever 28a. , 28b, 28c to open and close the same levers 28a, 28c.
switch circuits 43a, 43b, 43 that generate operation state signals representing the respective operation states of switches 43a, 28c;
c, and a microcomputer 44 that calculates the opening degree of the bypass valve 35 of the power steering device 30 based on these pickup signals and operation status signals and outputs a control signal representing the opening degree to the drive circuit 41. . The microcomputer 44 includes a program memory 44a that is composed of a read-only memory (ROM) and stores a program corresponding to the flowchart in FIG. 4, and a central processing unit (hereinafter referred to as CPU) 44b that executes this program.
The working memory 44c is made up of a writable memory (RAM) and temporarily stores data necessary for program execution, and the working memory 44c is made up of a read-only memory (ROM) to increase the vehicle speed U as shown in FIG. Bypass valve 35 increases accordingly.
A valve opening table 44d stores valve opening data for calculating the valve opening amount for each pattern number PN (1 to 6) determined according to each state of the lock mechanisms 26a, 26b, and 26c, and a vehicle speed sensor 42. and an input/output interface circuit (hereinafter referred to as I/O) 44e connected to the switch circuits 43a, 43b, and 43c, and a program memory 44 for these
a, a CPU 44b, a working memory 44c, a valve opening degree table 44d, and a bus 44f that commonly connects the I/O 44e.

The operation of the steering assistance amount control device of the vehicle power steering system in the four-wheel drive vehicle configured as described above will be explained using the flowchart of FIG. starts executing the program, and steps 80a~
Switch circuits 43a, 43b, 43c at 80f
The operating state signal from the control lever 28a, 28b, 28c is inputted via the I/O 44e to determine the operating state of the operating lever 28a, 28b, 28c, that is, the lock mechanism 26a, 26b, 26c.
determine whether or not it is in an active state. Now, assuming that the lock mechanisms 26a, 26b, and 26c are all inactive, the CPU 44b goes through steps 80a and 26c.
"NO", "NO", "NO" in sequence at 80b and 80c
It is determined that the lock mechanism 26 is locked in step 81a.
The pattern number PN representing the combination of states a, 26b, and 26c is set to "1", and in step 90 the pick-up signal from the vehicle speed sensor 42 is
The vehicle speed U of the vehicle is calculated by inputting it via O44e. After calculating the vehicle speed U, the CPU 44b selects the pattern number set to "1" above in step 91.
Based on PN and the calculated vehicle speed U, the valve opening amount is calculated by referring to the valve opening table 44d, and control data representing the calculated valve opening amount is sent to the drive circuit 41 via the I/O 44e in step 92. Output to. The drive circuit 41 stores the control data until new control data is supplied, and outputs a control signal corresponding to this control data to the bypass valve 35, so that the valve opening of the bypass valve 35 is adjusted to the valve opening degree calculated above. In such a state where the opening amount is set and controlled,
When the steering wheel 31 is rotated by the driver,
The hydraulic pump 3 discharges oil at a pressure corresponding to the above valve opening degree.
4 to the high pressure side oil chamber of the power cylinder 33D via the servo valve 33A, and the power cylinder 33B assists the driver's steering operation with a steering assist amount corresponding to the above-mentioned valve opening degree. At this time, if the vehicle speed U is small, the valve opening amount is small and the steering assist amount is relatively large, so the driver's steering operation is relatively light, and as the vehicle speed U increases, the valve opening amount increases and the steering assist amount is relatively large. Since the amount decreases, the driver's steering operation becomes heavier as the vehicle speed U increases. After processing step 92, the CPU 44b advances the program to step 80a and locks the lock mechanisms 26a, 26.
If the states of b and 26c are maintained as above, steps 80a, 80b, 80c, 81a,
The circulation processes 90 to 92 are continued, and the valve opening degree of the bypass valve 35, that is, the steering assist amount of the power cylinder 33B is controlled according to the vehicle speed U.

During the above circulation process, the operating levers 28a, 28b,
28c is operated, the CPU 44b performs the following processing through steps 80a to 80f and steps 81a to 81f according to the combination of the operating states of the levers 28a, 28b, and 28c, that is, the states of the locking mechanisms 26a, 26b, and 26c. Set the pattern number PN to any value from 2 to 6 as shown in the following. In this case, "pre-lock?" in step 80a means a comparative judgment as to whether or not the locking mechanism 26b is in an operating state, and steps 80b and 80e
"Rear lock?" means a comparative judgment as to whether or not the locking mechanism 26c is in the operating state, and the step 80
"Central lock?" of c, 80d, and 80f means a comparative judgment as to whether or not the lock mechanism 26a is in an operating state.

(1) If the locking mechanisms 26b and 26c are in the non-operating state and the locking mechanism 26a is in the operating state,
CPU44b steps 80a, 80b, 80
In step 81b, the pattern number PN is set to 2, and (2) the lock mechanism 26b is in the non-operating state (or in the operating state). , the lock mechanism 26c is in an activated state (or a non-activated state), and the lock mechanism 26a is in an activated state (or a non-activated state).
is inactive, the CPU 44b executes steps 80a, 80b, 80d (or step 80).
a, 80e, 80d) in sequence,
“YES”, “NO” (or “YES”, “NO”,
The pattern number PN is set to "3" in step 81c, and (3) the lock mechanism 26b is in the non-operating state (or operating state), and the lock mechanism 26c is in the operating state (or (inactive state) and locking mechanism 26a
is in the active state, the CPU 44b executes steps 80a, 80b, 80d (or steps 80a, 80d).
80e, 80d) sequentially "NO", "YES",
After determining "YES" (or "YES", "NO", "YES"), the pattern number PN is determined in step 81d.
(4) If the locking mechanisms 26b and 26c are in the operating state and the locking mechanism 26a is in the inactive state, the CPU 44b executes steps 80a, 80e,
At step 80f, it is determined as ``YES'', ``YES'', and ``NO'', and the pattern number PN is determined at step 81e.
(5) If all of the lock mechanisms 26b, 26c, and 26a are in the operating state, the CPU 44b goes to step 8.
"YES" sequentially at 0a, 80e, 80f,
“YES”, “YES” is determined, and step 81f
Set the pattern number PN to "6" in .

After setting the pattern number PN as above, the CPU
44b is the vehicle speed U at step 90, as described above.
After calculating, in step 91, the above “2” to “6” are calculated.
Pattern number PN and vehicle speed U set in either
The valve opening degree is calculated by referring to the valve opening degree table 44d based on , and the amount of steering assistance by the power cylinder 33B is controlled based on the calculated valve opening amount in step 92. As a result, as shown in FIG. 5, the amount of valve opening that increases as the vehicle speed U increases becomes smaller as the pattern number PN increases, and conversely, the amount of steering assist by the power cylinder 33B increases as the vehicle speed U increases. It decreases as the pattern number PN increases, and increases as the pattern number PN increases. After processing step 92, the CPU 44b advances the program to step 80a, and thereafter proceeds to steps 80a-80f, 81a-81f, 81a-81f, and the like as described above.
90 to 92 continue to be executed.

As can be understood from the above explanation of the operation, the amount of steering assistance provided by the power cylinder 33B when the steering wheel 31 is rotated decreases as the vehicle speed U increases through the processing in steps 90 to 92. Since the driver's steering force becomes heavier as the vehicle speed U increases, the steering stability of the vehicle improves. Further, the above-mentioned steering assist amount is calculated in steps 80a to 80a.
By the processes 80f, 81a to 81f, 91, and 92, the locking mechanisms 26a, 26b, and 26c increase in order from the case where all of them are in the non-operating state to the cases (1) to (5) above, so that the locking mechanisms 26a, 26b,
The turning of the left and right front wheels 10a, 10b and the left and right rear wheels 11a, 11b is restricted by the combination of the inoperative state or the active state of the differential gears 26c, that is, the combination of the differential operation enabled state or disabled state of the differential devices 22a, 22b, 22c. Even if the steering force of the vehicle increases in the above-mentioned order, the driver's steering force does not increase, and the driver does not operate the lock mechanism 26a, 2.
The vehicle can be steered with the same amount of steering force regardless of whether 6b or 26c are activated or not, and the steering performance of the vehicle is improved.

In addition, in the above embodiment, the operating lever 28
The operating force of a, 28b, 28c is transferred to the wires 27a, 2
Lock mechanisms 26a, 26 via 7b, 27c
However, the operating levers 28a, 28b, 28c are each replaced with operating switches, and the operation of these operating switches is electrically detected to electrically control the lock mechanisms 26a, 26b, 26c. It may also be controlled. In this case, an electromagnetic actuator for controlling the rocking of each lock lever 62 of the lock mechanisms 26a, 26b, and 26c is assembled into the case 60. In response to the operation of the operating switch, the electromagnetic actuator is driven to swing the lock lever 62 clockwise in FIG. 3.

Further, in the above embodiment, the differential devices 22a, 22
Lock mechanisms 26a, 26b, 26c on b, 22c
The present invention was applied to a four-wheel drive vehicle in which differential operation of the devices 26a, 26b, and 26c was enabled or disabled by attaching a This also applies to four-wheel drive vehicles that are equipped with a restriction device that does not restrict the differential operation of the differential device in its inactive state, but partially restricts the differential operation of the differential device in its activated state. applicable. In this case, a detection device is provided in the differential limiting device to detect whether or not the differential limiting device is limiting the differential operation of the differential device, and the differential limiting device limits the differential based on the output of this detection device. It is preferable to control the valve opening of the bypass valve 35 to be small when the device is not differentially limiting, and to increase the valve opening when the device is not differentially limiting. Even if the differential operation of the drive device is limited, the steering operation of the vehicle will not become difficult, and the same effects as in the above embodiments can be achieved.

Further, in the above embodiment, the locking mechanisms 26 are provided between the front and rear wheels, between the left and right front wheels, and between the left and right rear wheels.
Differential device 22 with a, 26b, 26c attached
a, 22b, and 22c, but the present invention can also be applied to vehicles that omit any of the lock mechanisms or differentials described above. In this case, the pattern number PN based on the combination of the operating states of the locking mechanisms 26a, 26b, and 26c may be appropriately set according to the number of locking mechanisms.

[Brief explanation of drawings]

Fig. 1 is a diagram corresponding to the configuration of the present invention described in the claims of the utility model registration, and Fig. 2 is a diagram of a four-wheel drive vehicle to which the present invention is applied, the power steering device of the vehicle, and its electric control device. A diagram showing an example; FIG. 3 is a diagram showing an example of the differential gear and lock mechanism of FIG. 2;
FIG. 4 is a flowchart corresponding to a program executed by the microcomputer shown in FIG. 2, and FIG. 5 is a diagram showing valve opening characteristics that change depending on vehicle speed. Explanation of symbols: 10a, 10b, 11a, 11b...Wheel, 2
0... Drive device, 21... Engine, 22a, 2
2b, 22c... differential gear, 26a, 26b, 2
6c...Lock mechanism, 28a, 28b, 28c...
...Operation lever, 30...Power steering device, 31...
Steering handle, 33A...Servo valve, 33B
...Power cylinder, 35 ...Bypass valve, 40
... Electric control device, 41 ... Drive circuit, 42 ...
Vehicle speed sensor, 43a, 43b, 43c... switch circuit, 44... microcomputer.

Claims (1)

[Scope of utility model registration request] The differential device provided between the first drive wheel and the second drive wheel is made differentially possible (or does not limit the differential) in its inactive state, and disabled (or not) in its active state. In a power steering system for a vehicle that is applied to a vehicle having a control mechanism (limiting differential differential) and reduces the steering operation force of the driver according to the amount of steering assistance provided by the steering assistance mechanism, the control mechanism is inoperative. a detection means for detecting a first steering assist amount when the control mechanism is in an inactive state in response to the detection; a control amount determining means for determining a control amount representing a second steering assist amount larger than the first steering assist amount; and a control signal corresponding to the determined control amount to be outputted to the steering assist mechanism to assist the steering assist mechanism. A steering assist amount control device for a power steering system for a vehicle, comprising: an output means for controlling the amount to the first or second steering assist amount.