JPS5873443A - Switching control unit of part time type four-wheel driven car - Google Patents

Abstract

PURPOSE:To prevent the power steering oil pressure from becoming deficient by switching to a two-wheel drive regardless of an operation to a four-wheel drive side under the condition of an low engine speed when the pressurized oil for power steering is utilized in an oil hydraulic clutch for switching between two and four-wheel drives. CONSTITUTION:A car speed judging circuit 24 and an engine speed judging circuit 28 are provided as the control unit of a valve 21 in a unit controlling the feed of the pressurized oil to an oil hydraulic clutch for switching between two and four-wheel drives by means of a solenoid valve 21. The car speed judging circuit 24 is constituted so that an L output is generated from a comparator 23 when the output from a car speed sensor 35 is zero while the car is at a halt, and the judging circuit 28 is constituted so as to generate an L output when the engine speed based on the output from an ignition coil 25 is equal to or less than a preset value. Then, when the outputs from both circuits 24, 28 are both at an L level, a transistor 30 is turned on, and even if a four-wheel drive judging circuit 34 judges a four-wheel drive, the signal from the circuit 34 is cancelled, thus closing the valve 21 and resulting in a two-wheel drive status.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a switching control device for a part-time four-wheel drive vehicle, in particular equipped with hydraulic power steering,
This invention relates to a system in which a hydraulic clutch is used to switch wheel drive, and the hydraulic pressure of a power steering pump is shared with the hydraulic oil 11 of the hydraulic clutch.

This is a part-time type 4-wheel drive system in which a hydraulic clutch is installed midway in the drive system from one rear wheel to the other for switching between 2 and 4-wheel drive, and the engagement or release of this hydraulic clutch enables 2-wheel or 4-wheel drive. A wheel drive vehicle has been proposed differently by the present t1 applicant. In this case, if it is equipped with an automatic transmission, it may be possible to use the hydraulic pressure of the hydraulic pump built into the transmission for automatic speed control for the oil If clutch 1, but with a manual transmission GL, side hydraulic pump oil)
f has no choice but to be used for a hydraulic clutch.

However, in a vehicle equipped with -1 hydraulic power thruster, the hydraulic pump for power steering is ljJ, so the oil i1 of this hydraulic pump is used for the 2.4 wheel drive switching described in -1-. It is conceivable that it could be used in hydraulic clutches for
When the vehicle is stopped, oil is supplied to the hydraulic clutch by manual operation when the vehicle is stopped, resulting in 14-wheel drive.If the engine speed is low and the pump oil passage is not sufficient, the oil pressure for power steering is insufficient. It becomes very difficult to turn the steering wheel. In addition, while the vehicle is stopped, in conventional embodiments, the switching state before the vehicle is stopped is maintained as it was, but in the four-wheel drive state, the above-mentioned oil supply to the hydraulic clutch and solenoid valve in the hydraulic circuit are required. This is undesirable as it wastes power and electricity by energizing.

As prior art regarding this type of switching M-, for example, there are publications such as Utility Model Publication No. 48-8821 and Japanese Patent Publication No. 53-23569, but in both cases, flJtl is used for switching during driving.
This is different from the one related to switching while the present invention is stopped.

The present invention was made in view of the above circumstances.In a type of hydraulic power steering that uses a hydraulic pump as the hydraulic power source for a hydraulic clutch for switching between 2 and 4 wheel drive, the engine speed decreases while the vehicle is stopped. Due to its small size, this part-time 4-wheel drive switch automatically switches to 2-wheel drive even when 4-wheel drive is being operated, ensuring the original steering performance of power steering and eliminating wasted power and electricity. The purpose is to provide a υ control device.

Hereinafter, one embodiment of the present invention will be specifically described with reference to the drawings. First, to explain the transmission system during four-wheel drive to which the present invention is applied in FIG. One end of the output shaft 6, which is connected to the input shaft 5 of the transmission 4 and takes out the power changed by the transmission 4, is connected to the final reduction gear 1 installed between the clutch 3 and the transmission 4. In other words, the power is transmitted to the front wheels. The other end of the output shaft 6 of the transmission 4 extends rearward and is connected to a rear drive shaft 10 via a hydraulic clutch 9 for four-wheel drive switching.
Further, transmission is configured from 0 to the rear wheels via the Noropeff shaft 11 and the final reduction gear %41i12. In this way, when the oil is drained from the hydraulic clutch 9 and it is in the released state, the power from the transmission 4 is finally transmitted to the front wheels only through the reduction gear 1 and 2.
Wheel drive driving is performed.

On the other hand, when the hydraulic clutch 9 is refueled, it becomes engaged and the power from the transmission 4 is transmitted through the hydraulic clutch 9 to the rear wheels in a light manner, resulting in four-wheel drive driving using the front and rear wheels. .

In Fig. 2, a hydraulic clutch 9 for switching between 2 and 4 wheel drive is shown.
To explain the hydraulic control system for the vehicle, the present invention is directed to vehicles equipped with hydraulic power steering. Therefore, a hydraulic servo mechanism 16 is provided which obtains a large operating force by hydraulic pressure through this power operation, and a hydraulic pump 11 driven by the engine 1 is connected to this mechanism 16 via an oil passage 18. Thus, in the power steering 13 having such a configuration, the hydraulic clutch 9 is connected to the hydraulic clutch 9 by the oil passage 19 branched from the oil passage 18 from the hydraulic pump 11.
- Hydraulic pump 1 for power steering;
1 is also used as a hydraulic power source for the hydraulic clutch 9. A solenoid valve 21 that is switched in response to a signal from a control device 20 is provided in the middle of the oil passage 19.

In detail about the m control device 2o in FIG. 3, a vehicle speed sensor 4J35 that generates a pulse according to the front wheel rotation speed;
A circuit 22 generates a voltage according to the vehicle speed according to the number of pulses from the vehicle speed sensor 35. The vehicle speed voltage from the circuit 22 is compared with a reference voltage, and a 0-level output is generated when the vehicle speed is zero and the vehicle is stopped. There is a medium speed determination circuit 24 on the right side of the comparator 23. Further, a circuit 26 similar to the above-mentioned one using the ignition coil 25, and a rotation speed determination circuit 28 having a comparator 21.
, and only when the outputs of these circuits 24 and 28 are low level, the NAND gate 29 is operated and the transistor 30 is
JlrJn is now available. On the other hand, a drive circuit 32 including a transistor 31 is connected to the solenoid valve 21, and a manually operated 2° four-wheel drive selector switch 33 is connected to the base side of the transistor 31. A four-wheel drive determination circuit 34 that automatically switches to drive is connected. Therefore, when the transmitter sides of transistors 1 to 3o described above are connected to the base sides of synisters 1 to 31, and the outputs of circuits 24 and 28 are at low level to the north, the drive circuit 32 is grounded by the transistor 30. Therefore, the signals from the changeover switch 33 and the circuit 34 are canceled. It goes without saying that the same configuration can be achieved even if a power generation type sensor is used as the medium speed sensor. To explain the operation of the device of the present invention configured in this way, the oil H type power steering 13
Hydraulic pressure from the hydraulic pump 17 is supplied to the oil E servo mechanism 16 that is the original power steering system, and the hydraulic clutch 9
I am also guided by Therefore, when the vehicle is running, the output of the comparator 23 of the medium speed determination circuit 24 is at a high level, so there is no output from the NAND gate 29, which turns off the transistor 30 and puts the drive circuit 32 into an operating state. Therefore, if the changeover switch 33 is operated to the two-wheel drive side and the circuit 34 does not determine that four-wheel drive should be performed, the transistor 31 is turned off and the solenoid pulp 21 is de-energized and operates to drain the oil. As a result, the hydraulic clutch 9 drains oil and becomes a released state, and two-wheel drive driving is performed. Next, when the circuit 34 determines that four-wheel drive is to be performed or the selector switch 33 is operated to the four-wheel drive side, the transistor 31 turns on.

For this reason, the solenoid pulp 21 is switched to supply oil to the hydraulic clutch 9 by energization, and the hydraulic pressure of the hydraulic pump 11 is supplied to the oil 11 clutch 9, which engages the oil 11 clutch 9, resulting in four-wheel drive driving. If the selector switch 33 remains operated to the four-wheel drive side when stopping after driving, the input signal continues on the base side of the transistor 31, and the four-wheel drive state is maintained. Become so. However, since the vehicle is stopped at this time, the output of the medium speed determination circuit 24 becomes the [G level] and becomes 1. When the engine speed is low, the output of the engine speed determination circuit 28 also goes to the low level, turning on the transistor 3o.

Therefore, the signal on the base side of the transistor 31 is turned low and the transistor 31 is turned off. Automatically switches to two-wheel drive. Therefore, when the engine speed is low while the vehicle is stopped, the oil pressure of the hydraulic pump 17 for power steering is not used for the hydraulic clutch 9, but is used only for no-steering.

As is clear from the above description, according to the present invention, when the pump hydraulic pressure for power steering is also used for the hydraulic clutch 9 for switching between 2 and 4 wheel drive, when the engine speed is low while the engine is stopped, the 4 wheels Even if the vehicle is being operated to drive, it switches to two-wheel drive and uses power steering exclusively, so the original power steering function can be utilized even when steering in this state. Then, when the engine speed increases at the time of starting, 4
If wheel drive was operated, it returns to that operating state and
It also functions as a wheel drive vehicle. Furthermore, when the engine is stopped and the engine speed is low, as described above, the solenoid pulp 21 is de-energized, and the hydraulic pump 11 for burnout steering is dedicated to it and becomes a two-wheel drive state. There is no wasteful consumption of power or electricity.

[Brief explanation of the drawing]

FIG. 1 is a skeleton diagram showing an example of a four-wheel drive system to which the present invention is applied, FIG. 2 is a hydraulic circuit diagram showing an embodiment of the device according to the present invention, and FIG. 3 is an electrical circuit diagram thereof. 4... Transmission, 7... Moe wheel final reduction device, 9... Hydraulic clutch, 12... Rear wheel final reduction device, 13 Kawayu 11
Complete power steering, 17 river hydraulic pump, 21...
・Solenoid pulp, 24...Medium speed judgment circuit, 25・
...Ignition coil, 28...L engine rotation speed determination circuit,
33...2.4 wheel drive selector switch, 34...4 wheel drive judgment circuit, 35゛...medium speed sensor. Patent applicant: Shige Tomito, Kuri Co., Ltd., patent attorney
Kobashi I6 Jun

Claims (1)

[Claims] Transmission is configured directly from the transmission to one of the front and rear wheels, and transmission is configured to the other of the front and rear wheels via a hydraulic clutch for switching between 2 and 4 wheel drive, and the hydraulic clutch is connected to the hydraulic power steering. A hydraulic circuit is configured to share the hydraulic pressure with the hydraulic pump, and a solenoid valve provided in the middle of the hydraulic circuit is electrically switched by a manual 2- and 4-wheel drive changeover switch and a signal from a 4-wheel drive determination circuit. In a part-time four-wheel drive vehicle, the system detects whether the vehicle is stopped or not and the magnitude of the engine speed based on the vehicle speed, and if the engine speed is low while the vehicle is stopped, the vehicle is always set to two-wheel drive. Switching control device for part-time 4-wheel drive vehicles.