Internal-combustion engines – Poppet valve operating mechanism – Hydraulic system
Patent
1993-11-29
1996-04-23
Lo, Weilun
Internal-combustion engines
Poppet valve operating mechanism
Hydraulic system
123 9017, 123 9031, 464 2, 74568R, F01L 134
Patent
active
055093833
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention generally relates to a hydraulic system with a hydraulic pump which is directly driven by an internal-combustion engine and more particularly to a hydraulic system with a hydraulic pump whose delivery rate is controlled at the inlet or at the outlet.
SUMMARY OF THE INVENTION
A hydraulic unit of this kind is described in German Patent Application No. 4,033,105. The operating fluid (hydraulic pressure fluid) of the pump, respectively of the combination of pumps, may be constituted by the lubricating agent of the internal-combustion engine, but alternatively a separate hydraulic pressure fluid circuit may be envisaged as well. If however, in an automotive vehicle for which a hydraulic system of this kind is provided, a plurality of hydraulic consumers exist and each consumer is supplied with hydraulic pressure fluid independently of all others, considerable constructional efforts, enormous space requirements and elevated costs are required.
It is, therefore, the object of the invention to further develop a hydraulic system of the kind under review in such a way that considerable reduction in cost, space requirements, weight and energy consumption are achieved.
This object is attained by utilizing the pump, which has as up to now exclusively been utilized for the variable adjustment of the camshafts, for other consumers so that their pumps may be dropped and, as a consequence, costs and space saved.
In this conjunction, both hydraulic devices may serve for the adjustment of camshafts, one camshaft adjusting device driven by each of the devices. In this context, in the case of engines with cylinders not being arranged in series (for example, V-shaped arrangement), the two camshafts can each actuate a series of inlet valves. It is another possibility that one of the two camshafts actuates exclusively inlet valves, whereas the other one actuates outlet valves.
According to another advantageous development, the second device serves a consumer which has to be supplied with hydraulic pressure fluid with priority, because it is of importance for safety reasons. This consumer may be the hydraulic operating cylinder of a hydraulic power steering system, a chassis control device, a booster of an automatic clutch or a brake system.
In particular, when an application requires that devices be equally or equivalently supplied with hydraulic pressure fluid, then solenoid valves provide a priority switching means such that, in a certain contingency, at least one of the two devices is actuated even in the event of a reduced pump capacity.
A very simple design connection giving precedence to a consumer of importance for safety reasons is an unlockable non-return valve, subject to pressure in the second device, interposed between the first device and the pump.
A very simple design connection for operating two hydraulically equivalent devices is a flow divider valve. In this instance both devices are supplied with hydraulic pressure fluid by a single pump circuit equivalently, without influencing each other. The hydraulic pressure fluid is delivered according to the demand of the devices by the flow divider valve. In particular, this type of connection is well-suited when both devices serve separate camshafts, each cam shaft exclusively controlling their respective outlet valves, or inlet valves. Another simple design connection preferable in the case of identical devices, in particular in devices actuating two camshafts, utilizes a proportional valve connected to the first device and a two position valve connected to the second device. Such an arrangement of connections is expedient if and when one device inlet camshaft and a second device outlet camshaft is to be adjusted, since for the optimization of the combustion within the engine the inlet camshaft has to be adjusted at finer steps than the outlet camshaft. In order to make sure that the other device (outlet valves) which is connected through the two-position valve is not influenced by the momentary function of the driving devi
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PCT Search Report (German language).
Fleck Franz
Huthmacher Winfried
Kahrs Manfred
Krines Hans-Gebhard
Kunz Gerhard
ITT Automotive Europe GmbH
Lo Weilun
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